WO2014116508A1

WO2014116508A1 - Metal organic frameworks as chemical carriers for downhole treatment applications

Info

Publication number: WO2014116508A1
Application number: PCT/US2014/011990
Authority: WO
Inventors: Li Jiang; Jian He; Gregory Kubala; Jesse C. Lee; Hanpu LIANG; Leiming Li; Jose Javier ALVAREZ BACHA CRUZ; Philip F. Sullivan; Lijun Lin; Wingki LEE; Andrey Mirakyan; Alejandro Pena; Gunnar Debruijn; Salvador AYALA
Original assignee: Schlumberger Canada Limited; Services Petroliers Schlumberger; Schlumberger Holdings Limited; Schlumberger Technology B.V.; Prad Research And Development Limited; Schlumberger Technology Corporation
Priority date: 2013-01-25
Filing date: 2014-01-17
Publication date: 2014-07-31

Abstract

Methods of treating a subterranean formation are disclosed that include introducing a treatment fluid into a subterranean formation, the treatment fluid containing a target chemical entity loaded into a MOF.

Description

METAL ORGANIC FRAMEWORKS AS CHEMICAL CARRIERS FOR DOWNHOLE

TREATMENT APPLICATIONS

[0001] BACKGROUND

[0002] Hydrocarbons (oil, natural gas, etc.) may be obtained from a subterranean geologic formation (a "reservoir") by drilling a well that penetrates the hydrocarbon-bearing formation. Well treatment methods often are used to increase hydrocarbon production by using a treatment fluid, which includes one or more active chemicals to modify a subterranean formation in a manner that ultimately increases oil or gas flow from the formation to the wellbore for removal to the surface.

[0003] For most well treatment methods there may be predetermined locations or specific zones of interest within various subterranean formations that are targeted for a specific treatment action. However, the active chemicals used in such well treatment methods may react and ultimately be spent before reaching the desired reaction site. Particularly, if such active chemicals are highly reactive and/or responsive to one or more of the other components in the treatment fluids or the subterranean formation itself. In such situations, temporarily storing and/or chemically isolating one or more of the active chemicals in a high capacity carrier until the chemical is to be reacted at the predetermined treatment location or target treatment zone can minimize the inefficiencies associated with treatment of formations or zones that are not of interest.

[0004] SUMMARY

[0005] This summary is provided to introduce a selection of concepts that are further described below in the detailed description. This summary is not intended to identify key or essential features of the claimed subject matter, nor is it intended to be used as an aid in limiting the scope of the claimed subject matter.

[0006] In some embodiments, the present disclosure relates to fluids for treating a subterranean formation. Such fluids may include a solvent, and a composition containing a target chemical entity loaded into a metal organic framework (MOF), where the MOF includes a plurality of pores having a plurality of accessible sites for the reversible uptake of the target chemical entity. The present disclosure also relates to methods for treating a subterranean formation, the methods including introducing the above-mentioned fluid into a subterranean formation. In some of the methods of the present disclosure, the target chemical entity may be temporarily stored in the MOF.

[0007] In some embodiments, the present disclosure relates to fluids for treating a subterranean formation including a solvent, a crosslinkable component, and a crosslinking composition containing a crosslinker loaded into a MOF, where the MOF includes a plurality of pores having a plurality of accessible sites for a reversible uptake of the crosslinker. The present disclosure also relates to methods for treating a subterranean formation, the methods including introducing the above-mentioned fluid, which contains a crosslinker-loaded MOF, into a subterranean formation and increasing the viscosity of the fluid by reacting the crosslinkable component with a crosslinker that has diffused out of the crosslinker-loaded MOF.

[0008] In some embodiments, the present disclosure relates to fluids for treating a subterranean formation including a solvent, a breaker loaded into a MOF, where the MOF includes a plurality of pores having a plurality of accessible sites for a reversible uptake of the breaker. The present disclosure also relates to methods for treating a subterranean formation, the methods including introducing the above-mentioned fluid, which contains a breaker-loaded MOF, into a subterranean formation and reducing the viscosity of the viscosified fluid by reacting the viscosified fluid with a breaker that has diffused out of the breaker- loaded MOF.

[0009] In some embodiments, the present disclosure relates to fluids for treating a subterranean formation including a solvent, an acid, acidizing agent, or base loaded into a MOF, where the MOF includes a plurality of pores having a plurality of accessible sites for a reversible uptake of the acid, acidizing agent, or base. The present disclosure also relates to methods for treating a subterranean formation, the methods including introducing the above-mentioned fluid, which contains an acid-loaded MOF, acidizing agent-loaded MOF, and/or base-loaded MOF, into a subterranean formation.

[0010] BRIEF DESCRIPTION OF THE DRAWINGS

[0011] The manner in which the objectives of the present disclosure and other desirable characteristics may be obtained is explained in the following description and attached drawings in which: [0012] FIG. 1 is an illustration of the particle size distribution of the two MOF samples

(MOF-1 and MOF-2).

[0013] FIG. 2 is an illustration of the rheology profile of the crosslinking of a linear gel of gum by crosslinker loaded MOF-1 samples and a control sample.

[0014] FIG. 3 is an illustration of a device including an overhead mixer and a rheometer used for the rheology test for the crosslinker loaded MOF-1 samples.

[0015] FIG. 4 is an illustration of the rheology profile of the crosslinking of a linear gel of gum by crosslinker loaded MOF-2 samples and a control sample.

[0016] FIG. 5 is an illustration of the thermogravimetric analysis of the crosslinker loaded MOF-1 sample.

[0017] FIG. 6 is an illustration of the differential scanning calorimetric analysis of the crosslinker loaded MOF-1 sample.

[0018] FIG. 7 is an illustration of the differential scanning calorimetric analysis of the crosslinker loaded MOF-2 sample.

[0019] FIG. 8 shows a plot of the viscosity over time of crosslinked gelled polymer solutions (Example 1) containing a breaker (l,l-di(tert-butylperoxy)-3,3,5- trimethylcyclohexane) .

[0020] FIG. 9 shows a plot of the viscosity over time of crosslinked gelled polymer solutions (Example 2) containing a breaker (l,l-di(tert-butylperoxy)-3,3,5- trimethylcyclohexane) .

[0021] FIG. 10 shows a plot of the viscosity over time of crosslinked gelled polymer solutions (Example 3) containing a breaker (l,l-di(tert-butylperoxy)-3,3,5- trimethylcyclohexane) .

[0022] FIG. 11 shows a plot of the viscosity over time of crosslinked gelled polymer solutions (Example 4) containing a breaker (sodium bromate).

[0023] FIG. 12 shows a plot of the viscosity over time of crosslinked gelled polymer solutions (Example 5) containing a breaker (l,l-di(tert-butylperoxy)-3,3,5- trimethylcyclohexane) . [0024] DETAILED DESCRIPTION

[0025] In the following description, numerous details are set forth to provide an understanding of the present disclosure. However, it may be understood by those skilled in the art that the methods of the present disclosure may be practiced without these details and that numerous variations or modifications from the described embodiments may be possible.

[0026] At the outset, it should be noted that in the development of any such actual embodiment, numerous implementation-specific decisions may be made to achieve the developer's specific goals, such as compliance with system related and business related constraints, which will vary from one implementation to another. Moreover, it will be appreciated that such a development effort might be complex and time consuming but would nevertheless be a routine undertaking for those of ordinary skill in the art having the benefit of this disclosure. In addition, the composition used/disclosed herein can also comprise some components other than those cited. In the summary and this detailed description, each numerical value should be read once as modified by the term "about" (unless already expressly so modified), and then read again as not so modified unless otherwise indicated in context. Also, in the summary and this detailed description, it should be understood that a range listed or described as being useful, suitable, or the like, is intended to include support for any conceivable sub-range within the range at least because every point within the range, including the end points, is to be considered as having been stated. For example, "a range of from 1 to 10" is to be read as indicating each possible number along the continuum between about 1 and about 10. Furthermore, one or more of the data points in the present examples may be combined together, or may be combined with one of the data points in the specification to create a range, and thus include each possible value or number within this range. Thus, (1) even if numerous specific data points within the range are explicitly identified, (2) even if reference is made to a few specific data points within the range, or (3) even when no data points within the range are explicitly identified, it is to be understood (i) that the inventors appreciate and understand that any conceivable data point within the range is to be considered to have been specified, and (ii) that the inventors possessed knowledge of the entire range, each conceivable sub-range within the range, and each conceivable point within the range. Furthermore, the subject matter of this application illustratively disclosed herein suitably may be practiced in the absence of any element(s) that are not specifically disclosed herein. [0027] The methods of the present disclosure relate to introducing treatment fluids, such as treatment fluids comprising a metal organic framework ("MOF") loaded with one or more target chemical entities, such as crosslinkers, breakers, acids, bases and/or other atoms or molecules, into a subterranean formation. Such treatment fluids may be introduced during methods that may be applied at any time in the life cycle of a reservoir, field or oilfield; for example, the methods and treatment fluids of the present disclosure may be employed in any desired downhole application (such as, for example, stimulation) at any time in the life cycle of a reservoir, field or oilfield.

[0028] As used herein, the term "treatment fluid," refers to any fluid used in a

subterranean operation in conjunction with a desired function and/or for a desired purpose. The term "treatment," or "treating," does not imply any particular action by the fluid. For example, a treatment fluid (such as a treatment fluid comprising a MOF loaded with one or more target chemical entities) introduced into a subterranean formation subsequent to a leading-edge fluid may be a hydraulic fracturing fluid, an acidizing fluid (acid fracturing, acid diverting fluid), a stimulation fluid, a sand control fluid, a completion fluid, a wellbore consolidation fluid, a remediation treatment fluid, a cementing fluid, a driller fluid, a frac-packing fluid, or gravel packing fluid. The methods of the present disclosure in which a MOF loaded with one or more target chemical entities is employed, and treatment fluids comprising a MOF loaded with one or more target chemical entities may be used in full-scale operations, pills, or any combination thereof. As used herein, a "pill" is a type of relatively small volume of specially prepared treatment fluid, such as a treatment fluid comprising a MOF loaded with one or more target chemical entities, placed or circulated in the wellbore.

[0029] As used herein, the term "treating temperature," refers to the temperature of the treatment fluid that is observed while the treatment fluid is performing its desired function and/or desired purpose.

[0030] The term "fracturing" refers to the process and methods of breaking down a geological formation and creating a fracture, such as the rock formation around a wellbore, by pumping fluid at very high pressures (pressure above the determined closure pressure of the formation), in order to increase production rates from or injection rates into a hydrocarbon reservoir. The fracturing methods of the present disclosure may include a MOF loaded with one or more target chemical entities in one or more of the treatment fluids, but otherwise use conventional techniques known in the art.

[0031] In embodiments, the treatment fluids of the present disclosure may be introduced into a wellbore. A "wellbore" may be any type of well, including, but not limited to, a producing well, a non-producing well, an injection well, a fluid disposal well, an experimental well, an exploratory well, and the like. Wellbores may be vertical, horizontal, deviated some angle between vertical and horizontal, and combinations thereof, for example a vertical well with a non-vertical component.

[0032] The term "field" includes land-based (surface and sub-surface) and sub-seabed applications. The term "oilfield," as used herein, includes hydrocarbon oil and gas reservoirs, and formations or portions of formations where hydrocarbon oil and gas are expected but may additionally contain other materials such as water, brine, or some other composition.

[0033] The terms "MOF" or "porous MOF" refer, for example, to a porous metal organic framework comprising at least one bidentate organic compound having a coordinate bond to at least one metal ion. Suitable MOFs for the methods of the present disclosure comprise a plurality of pores having a plurality of accessible sites for the reversible uptake of one or more target chemical entities. Examples of MOFs suitable for the methods of the present disclosure may be found in U.S. Patent Nos. 7,202,385, 7,880,026, 8,133,301, 8,269,029, 8,322,534 and U.S. Patent Application Publication Nos. 2012/0085235, 2012/0296095, 2012/0115961, 2012/0259117, and 2011/0319604, the disclosures of which are hereby incorporated by reference in their entireties.

[0034] The term "target chemical entity" refers, for example, to one or more atoms, molecules, and/or ions that may be used in a subterranean operation in conjunction with carrying out desired application and/or for achieving a desired function. For example, target chemical entities may include crosslinkers, breakers, acids, bases and/or other chemicals.

[0035] In embodiments, the MOFs, such as porous MOFs comprising a plurality of accessible pores, and/or composite MOFs (loaded MOFs coated with a polymeric material, such as an inter-polymer complex), may be loaded with a target chemical entity, such as a target chemical entity that can reversibly associate with the MOF. [0036] The plurality of pores of the porous MOF may include micropores and/or mesopores. "Micropores" are defined as those having a diameter of about 2 nm or less, such as a diameter in the range of from about 2 nm to about 0.01 nm, or a diameter in the range of from about 1 nm to about 0.1 nm; and "mesopores" are defined by a diameter in the range of from about 2 to about 50 nm, such as a diameter in the range of from about 5 nm to about 40 nm, or a diameter in the range of from about 10 nm to about 30 nm, in each case according to the definition as stated in Pure Applied Chem. 45, page 71, in particular on page 79 (1976). The presence of micropores and/or mesopores can be checked with the aid of sorption measurements, these measurements determining the absorptivity of the MOF for nitrogen at 77 Kelvin according to DIN 66135, DIN 66131 and/or DIN 66134. In embodiments, the specific surface area, calculated using the Langmuir model according to DIN 66135 (DIN 66131, 66134) for a MOF in powder form, may be from about 500 m²/g to about 15,000 m²/g, or from about 1,500 m²/g to about 12,000 m²/g, or from about 2,500 m²/g to about 10,000 m²/g.

[0037] In embodiments, the MOFs, and/or MOF composites, when loaded with the target chemical entity, act as a vehicle that temporarily stores and/or chemically isolates the target chemical entity while it is being transported to the target treatment zone or target subterranean formation, where it may diffuse and/or be released from the loaded MOF, such as after a predetermined period of time or after exposure to a predetermined downhole condition (such as, for example, temperature or pressure) or predetermined downhole environment (such as for example, the surrounding chemicals and the phase thereof, including pH, ionic strength, temperature, pressure, etc.,). After the target chemical entity diffuses and/or is released from the loaded MOF it is then available for its intended function and/or application, for example, as a crosslinker, a breaker, or an acidizing agent.

[0038] As discussed in the embodiments below, the temporary storage and/or chemical isolation of the target chemical entity in the MOFs prevents the premature reaction and/or use of the target chemical entity for a predetermined period of time, such as before reaching the target treatment zone or target subterranean formation, and/or before the MOF is exposed to a predetermined downhole condition (such as, for example, temperature or pressure) or

predetermined downhole environment (such as for example, the surrounding chemicals and the phase thereof, including pH, ionic strength, temperature, pressure, etc.,), which may result in the target chemical entity diffusing from or exiting the MOF. Premature release of the target chemical entity from the MOF may result in premature use and/or reaction of the target chemical, such as a reaction with the subterranean formation itself, a reaction with components in the bulk of the treatment fluid and/or a reaction with other downhole components.

[0039] In some embodiments, most of the target chemical entity present in the MOF system arrives at the target treatment zone or target subterranean formation before reacting, for example, at least 95% by weight of the target chemical entity initially present in the MOF system, or at least 99% by weight of the target chemical entity initially present in the MOF system, or at least 99.9% by weight of the target chemical entity initially present within the MOF system, may arrive at the target treatment zone or target subterranean formation before leaving the MOF system (for example, by diffusion) and reacting in its intended capacity, for example, as a crosslinker, a breaker, or an acidizing agent.

[0040] In embodiments, the porous MOFs used in the methods of the present disclosure may temporarily store and/or chemically isolate the target chemical entity initially present in the treatment fluid, such as at least 90% by weight of the target chemical entity initially present within the treatment fluid, or at least 95% by weight of the target chemical entity initially present within the treatment fluid, or at least 99.9% by weight of the target chemical entity initially present within the treatment fluid. For example, the target chemical entity may be initially stored in the MOF, while its concentration in the treatment fluid is effectively zero.

[0041] For example, where the MOF is loaded with a base, such as sodium hydroxide, the pH of the treatment fluid will increase as the base diffuses from and/or is released from the MOF. In such embodiments, the base loaded MOF, such as a MOF loaded with a strong base, like sodium hydroxide, may be distributed in a polymeric material, and/or coated in a polymeric material, to form a composite MOF. In embodiments, the polymeric material of the composite MOF may be known to be stable to exposure to strong bases, and may be a material such as a gel and/or inter-polymer complex (IPC) comprising polyacrylamide (greater than 1%) crosslinked by a non-metallic crosslinker, as described in U.S. Patent Application Publication No.

2012/0138294, discussed in more detail below. In such embodiments, the "base-loaded" MOF may be present in the treatment fluid in a sufficient amount to result in a treatment fluid pH (in the treatment zone of interest) that is sufficient to perform the desired function and/or for a desired purpose of the treatment fluid (such as those described above and below). [0042] The target treatment zone or subterranean formation of interest will be readily apparent to those skilled in the art and may depend on the selected downhole application, and the identity of the target chemical entity, which may be, for example, a crosslinker, a breaker, or an acidizing agent.

[0043] The metal in the MOF framework may be any appropriate metal that is capable of forming a porous MOF that possesses a structure allowing for the reversible loading of an effective amount of the target chemical entity, such as, for example, a crosslinker, a breaker, or an acidizing agent, for the desired downhole application. For example, the metal may be selected from one of the known metal containing groups of the periodic table, such as groups la, Ila, Ilia, IVa to Villa and lb to VIb of the periodic table, including metals such as, for example, Mg, Ca, Sr, Ba, Sc, Y, Ti, Zr, Hf, V, Nb, Ta, Cr, Mo, W, Mn, Re, Fe, Ro, Os, Co, Rh, Ir, Ni, Pd, Pt, Cu, Ag, Au, Zn, Cd, Hg, Al, Ga, In, Ti, Si, Ge, Sn, Pb, As, Sb and Bi. Ionic states of the above metals may include, for example, Mg²⁺, Ca²⁺, Sr²⁺, Ba²⁺, Sc³⁺, Y³⁺, Ti⁴⁺, Zr⁴⁺, HF⁴⁺, V⁴⁺, V³⁺, V²⁺, Nb³⁺, Ta³⁺, Cr³⁺, Mo³⁺, W³⁺, Mn²⁺, Re³⁺, Re²⁺, Fe³⁺, Fe²⁺, Ru³⁺, Ru²⁺, Os³⁺, Os²⁺, Co³⁺, Co²⁺, Rh²⁺, Rh⁺, Ir²⁺, Ir⁺, Ni²⁺, Ni⁺, Pd²⁺, Pd⁺, Pt²⁺, Pt⁺, Cu²⁺, Cu⁺, Ag⁺, Au⁺, Zn²⁺, Cd²⁺, Hg²⁺, Al³⁺, Ga³⁺, In³⁺, Ti³⁺, Si⁴⁺, Si²⁺, Ge⁴⁺, Ge²⁺, Sn⁴⁺, Sn²⁺, Pb⁴⁺, Pb²⁺, As⁵⁺, As³⁺, As⁺, Sb⁵⁺, Sb³⁺, Sb⁺, Bi⁵⁺, Bi³⁺ and Bi⁺.

[0044] The phrase "at least one bidentate organic compound" refers to an organic compound that comprises at least one functional group that is capable of forming at least two bonds, such as two coordinate bonds, to a given metal ion and/or one coordinate bond to two or more metal atoms.

[0045] For example, the following functional groups may be suitable functional groups via which the coordinate bonds can be formed: -C0₂H, -CS₂, -N0₂, -B(OH)₂, -S0₃H, - Si(OH)₃, -Ge(OH)₃, -Sn(OH)₃, -Si(SH)₄, -Ge(SH)₄, -Sn(SH)₃, -P0₃H, -As0₃H, -As0₄H, - P(SH)₃, -As(SH)₃, -CH(RSH)₂, -C(RSH)₃, -CH(RNH₂)₂, -(RNH₂)₃, -CH(ROH)₂, -C(ROH)₃, -CH(RCN)₂, -C(RCN)₃, where R is, for example, an alkylene group having 1, 2, 3, 4 or 5 carbon atoms, such as, for example, a methylene, ethylene, n-propylene, isopropylene, n-butylene, isobutylene, tert-butylene or n-pentylene group, or an aryl group comprising one or two aromatic nuclei, such as, for example, two C₆ rings which may be condensed and, independently of one another, may be suitably substituted by at least one substituent in each case, and/or, independently of one another, may comprise in each case at least one hetero atom, such as, for example, N, O and/or S. In embodiments, functional groups in which the above-mentioned radical R is not present may also be suitable, such as, for example, -CH(SH)₂, -C(SH)₃, - CH(NH₂)₂, -C(NH₂)₃, -CH(OH)₂, -C(OH)₃, -CH(CN)₂ or -C(CN)₃.

[0046] The at least one functional group may be bonded to any suitable organic compound, provided that the organic compound having this functional group is capable of forming the coordinate bond(s) and of producing a porous MOF that is stable (thermally and chemically) in the presence of an effective amount of the target chemical entity for the desired downhole application or function such as, for example, crosslinking, breaking, or acidizing.

[0047] In embodiments, the at least one bidentate organic compound may be an organic compound that comprises at least two functional groups. The at least two functional groups may be bonded to any suitable organic compound, provided that the organic compound having these functional groups is capable of forming the coordinate bond and of producing a porous MOF that is stable (thermally and chemically) in the presence of an effective amount of the target chemical entity (such as, for example, a crosslinker, a breaker, acid, base, or an acidizing agent) and in the intended downhole environment (for example, the surrounding chemicals and the phase thereof, including pH, ionic strength, temperature, pressure, etc.,) for the desired downhole application. In embodiments, the porous MOFs (and/or the porous MOFs loaded with the target chemical entity) may stable (for example, less than 2% by mass deterioration or decomposition, or less than 1% by mass deterioration or decomposition) in air, aqueous and/or organic solvents (even at the pH ranges discussed below), and/or downhole conditions (such as, for example, temperature or pressure) or downhole environment (such as for example, the surrounding chemicals and the phase thereof, including pH, ionic strength, temperature, pressure, etc.,), for periods greater than a week, such as periods from a about a week to multiple years, such as from about a month to about a year. In embodiments, the porous MOFs (and/or the porous MOFs loaded with the target chemical entity) may stable (for example, less than 2% by mass deterioration or decomposition, or less than 1% by mass deterioration or decomposition) for periods greater than a month, or greater than 6 months.

[0048] In embodiments, the organic compounds that comprise the at least one functional group (or the at least two functional groups) may be derived from a saturated aliphatic compound, an unsaturated aliphatic compound, an aromatic compound, or a compound that is both aliphatic and aromatic. The aliphatic compound (or the aliphatic moiety of the compound that is both aliphatic and aromatic) may be linear and/or branched and/or cyclic. For example, the aliphatic compound (or the aliphatic moiety of the compound which is both aliphatic and aromatic) may comprise from 1 to about 15 carbon atoms, such as from about 2 to about 14 carbon atoms, or from about 3 to about 12 carbon atoms.

[0049] The aromatic compound or the aromatic moiety of the compound that is both aromatic and aliphatic may have one or more rings, such as, for example, two, three, four or five rings. Such rings may be separated from one another and/or be present in fused form.

Independently of one another, each ring may comprise at least one hetero atom, such as, for example, N, O, S, B, P, Si or Al.

[0050] In embodiments, the at least one bidentate organic compound may be a dicarboxylic acid, a tricarboxylic acid, tetracarboxylic acid, or an imidazole or other derivatives of amine(s).

[0051] Suitable dicarboxylic acids may include, for example, oxalic acid, succinic acid, tartaric acid, 1 ,4-butanedicarboxylic acid, 4-oxopyran-2,6-dicarboxylic acid, 1,6- hexanedicarboxylic acid, decanedicarboxylic acid, 1,8-heptadecanedicarboxylic acid, 1,9- heptadecanedicarboxylic acid, heptadecanedicarboxylic acid, acetylenedicarboxylic acid, 1 ,2- benzenedicarboxylic acid, 2,3-pyridinedicarboxylic acid, pyridine -2, 3 -dicarboxylic acid, 1,3- butadiene-l,4-dicarboxylic acid, 1 ,4-benzenedicarboxylic acid, p-benzenedicarboxylic acid, imidazole-2,4-dicarboxylic acid, 2-methylquinoline-3,4-dicarboxylic acid, quinoline-2,4- dicarboxylic acid, quinoxaline-2,3-dicarboxylic acid, 6-chloroquinoxaline-2,3-dicarboxylic acid, 4,4'-diaminophenyl ethane-3, 3 '-dicarboxylic acid, quinoline-3,4-dicarboxylic acid, 7-chloro-4- hydroxyquinoline-2,8-dicarboxylic acid, diimidodicarboxylic acid, pyridine-2,6-dicarboxylic acid, 2-methylimidazole-4,5-dicarboxylic acid, thiophene-3,4-dicarboxylic acid, 2- isopropylimidazole-4,5-dicarboxylic acid, tetrahydropyran-4,4-dicarboxylic acid, perylene-3,9- dicarboxylic acid, perylenedicarboxylic acid, Pluriol E 200-dicarboxylic acid, 3,6- dioxaoctanedicarboxylic acid, 3,5-cyclohexadiene-l,2-dicarboxylic acid, octadicarboxylic acid, pentane-3,3-carboxylic acid, 4,4'-diamino-l, -diphenyl-3,3'-dicarboxylic acid, 4,4'- diaminodiphenyl-3, 3 '-dicarboxylic acid, benzidene-3, 3 '-dicarboxylic acid, 1,4- bis(phenylamino)benzene-2,5-dicarboxylic acid, l, -dinaphthyl-5,5'-dicarboxylic acid, 7-chloro- 8-methylquinoline-2,3-dicarboxylic acid, l-anilinoanthraquinone-2,4'-dicarboxylic acid, polytetrahydrofuran-250-dicarboxylic acid, 1 ,4-bis(carboxymethyl)piperazine-2, 3 -dicarboxylic acid, 7-chloroquinoline-3,8-dicarboxylic acid, l-(4-carboxy)phenyl-3-(4- chloro)phenylpyrazoline-4,5-dicarboxylic acid, 1 ,4,5,6,7,7-hexachloro-5-norbornene-2,3- dicarboxylic acid, phenylindanedicarboxylic acid, l,3-dibenzyl-2-oxoimidazoline-4,5- dicarboxylic acid, 1 ,4-cyclohexanedicarboxylic acid, naphthalene- 1,8-dicarboxylic acid, 2- benzoylbenzene- 1 ,3 -dicarboxylic acid, 1 ,3-dibenzyl-2-oxoimidazolidine-4,5-cis-dicarboxylic acid, 2,2'-biquinoline-4,4'-dicarboxylic acid, pyridine-3,4-dicarboxylic acid, 3,6,9- trioxaundecanedicarboxylic acid, O-hydroxybenzophenonedicarboxylic acid, Pluriol E 300- dicarboxylic acid, Pluriol E 400-dicarboxylic acid, Pluriol E 600-dicarboxylic acid, pyrazole-3,4- dicarboxylic acid, 2,3-pyrazinedicarboxylic acid, 5,6-dimethyl-2,3-pyrazinedicarboxylic acid, 4,4'-diaminodiphenyl ether diimidodicarboxylic acid, 4,4'- diaminodiphenylmethanediimidodicarboxylic acid, 4,4'-diaminodiphenyl sulfone

diimidodicarboxylic acid, 2,6-naphthalenedicarboxylic acid, 1,3-adamantanedicarboxylic acid, 1,8-naphthalenedicarboxylic acid, 2,3-naphthalenedicarboxylic acid, 8-methoxy-2,3- naphthalenedicarboxylic acid, 8-nitro-2,3-naphthalenecarboxylic acid, 8-sulfo-2,3- naphthalenedicarboxylic acid, anthracene-2,3-dicarboxylic acid, 2',3'-diphenyl-p-terphenyl-4,4"- dicarboxylic acid, diphenyl ether 4,4'-dicarboxylic acid, imidazole-4,5-dicarboxylic acid, 4(1H)- oxothiochromene-2,8-dicarboxylic acid, 5-tert-butyl-l,3-benzenedicarboxylic acid, 7,8- quinolinedicarboxylic acid, 4,5-imidazoledicarboxylic acid, 4-cyclohexene-l,2-dicarboxylic acid, hexatricontanedicarboxylic acid, tetradecanedicarboxylic acid, 1 ,7-heptadicarboxylic acid, 5-hydroxy-l,3-benzenedicarboxylic acid, pyrazine-2,3-dicarboxylic acid, furan-2,5-dicarboxylic acid, l-nonene-6,9-dicarboxylic acid, eicosenedicarboxylic acid, 4,4'- dihydroxydiphenylmethane-3 ,3 '-dicarboxylic acid, 1 -amino-4-methyl-9, 10-dioxo-9, 10- dihydroanthracene-2,3-dicarboxylic acid, 2,5-pyridinedicarboxylic acid, cyclohexene-2,3- dicarboxylic acid, 2,9-dichlorofluoroubin-4,l 1 -dicarboxylic acid, 7-chloro-3-mnethylquinoline- 6, 8 -dicarboxylic acid, 2,4-dichlorobenzophenone-2',5'-dicarboxylic acid, 1,3- benzenedicarboxylic acid, 2,6-pyridinedicarboxylic acid, l-methylpyrrole-3,4-dicarboxylic acid, 1 -benzyl- lH-pyrrole-3,4-dicarboxylic acid, anthraquinone-l,5-dicarboxylic acid, 3,5- pyrazoledicarboxylic acid, 2-nitrobenzene-l,4-dicarboxylic acid, heptane- 1 ,7-dicarboxylic acid, cyclobutane-l,l-dicarboxylic acid, 1,14-tetradecanedicarboxylic acid, 5,6-dehydronorbornane- 2,3-dicarboxylic acid, 5-ethyl-2,3-pyridinedicarboxylic acid or salts thereof.

[0052] Suitable tricarboxylic acids may include, for example, 2 -hydroxy- 1,2,3- propanetricarboxylic acid, 7-chloro-2,3,8-quinolinetricarboxylic acid, 1,2,4-benzenetricarboxylic acid, 1,2,4-butanetricarboxylic acid, 2-phosphon-l,2,4-butanetricarboxylic acid, 1,3,5- benzenetricarboxylic acid, l-hydroxy-l,2,3-propanetricarboxylic acid, 4,5-dihydro-4,5-dioxo- lH-pyrrolo[2,3-F]quinoline-2,7,9-tricarboxylic acid, 5-acetyl-3-amino-6-methylbenzene-l ,2,4- tricarboxylic acid, 3-amino-5-benzoyl-6-methylbenzene-l,2,4-tricarboxylic acid, 1,2,3- propanetricarboxylic acid or aurinetricarboxylic acid.

[0053] Suitable tetracarboxylic acids may include, for example, l,l-dioxoperylo[l,12-

BCD]thiophene-3,4,9,10-tetracarboxylic acid, perylene-tetracarboxylic acids, such as perylene- 3,4,9, 10-tetracarboxylic acid or perylene-l,12-sulfonyl-3,4,9,10-tetracarboxylic acid, butanetetracarboxylic acids, such as 1,2,3,4-butanetetracarboxylic acid or meso-1,2,3,4- butanetetracarboxylic acid, decane-2,4,6,8-tetracarboxylic acid, 1,4,7,10,13,16- hexaoxacyclooctadecane-2,3,11,12-tetracarboxylic acid, 1,2,4,5-benzenetetracarboxylic acid, 1,2,11,12-dodecanetetracarboxylic acid, 1,2,5,6-hexanetetracarboxylic acid, 1,2,7,8- octanetetracarboxylic acid, 1,4,5, 8-naphthalenetetracarboxylic acid, 1,2,9,10- decanetetracarboxylic acid, benzophenonetetracarboxylic acid, 3,3',4,4'- benzophenonetetracarboxylic acid, tetrahydrofurantetracarboxylic acid or

cyclopentanetetracarboxylic acids, such as cyclopentane-l,2,3,4-tetracarboxylic acid.

[0054] In addition to these at least bidentate organic compounds, the MOF may also comprise one or more monodentate ligands.

[0055] Suitable solvents for the preparation of the MOF may include any known solvent, such as, for example, ethanol, dimethylformamide, toluene, methanol, chlorobenzene, diethylformamide, dimethyl sulfoxide, water, hydrogen peroxide, methylamine, sodium hydroxide solution, N-methylpyrrolidone ether, acetonitrile, benzylchloride, triethylamine, ethylene glycol and mixtures thereof. Further metal ions, polydentate organic compounds and solvents for the preparation of porous MOFs may be found in U.S. Pat. No. 5,648,508, the disclosure of which is hereby incorporated by reference in its entirety. [0056] In embodiments, the at least one bidentate organic compound or ligands are selected to form a porous MOF having pores, cages and/or channels of a predetermined size and shape, such that the functional groups of the porous MOF(s) may be selected to non-covalently interact with the functional groups of a preselected target chemical entity for the desired downhole application. In embodiments, specific bidentate organic compounds or ligands may be selected and/or further functionalized such that functional groups line the cages and channels, and/or the pores.

[0057] In embodiments, the target chemical entity may be a molecule containing at least one functional group that is complementary to one or more sites in the plurality of pores in the MOF. Such complementary functional groups may have a high affinity via noncovalent interactions for the one or more sites in the plurality of pores in the MOF. In such embodiments, the MOF may include at least one bidentate organic compound (or one or more of the other ligands) that may be functionalized in order to create sites with a desired functionality, such as sites having a functionality that is complementary to at least one functional group on the preselected target chemical entity. This ability of MOFs to be functionalized is useful because the pores may be lined with a high concentration of ordered sites whose properties, such as hydrophobic, hydrophilic, polar, non-polar, and/or steric properties, can be tailored to match the functionality of the target chemical entity and thereby allow for the tuning of the MOF/target chemical entity system to achieve the desired diffusion/release rates of the target chemical entity from the pores of the MOF.

[0058] In embodiments, the target chemical entity may be functionalized with one or more functional groups, such as, for example, to enhance the uptake level and/or modulate the absorption/release kinetics of the target chemical entity from the pores of the MOF.

[0059] Functional groups that may be present (or added) to the MOF and/or the target chemical entity include, for example, halogens, alcohols, ethers, ketones, carboxylic acids, esters, carbonates, amines, amides, imines, ureas, aldehydes, isocyanates, tosylates, alkanes, alkenes, alkynes, or combinations thereof.

[0060] In embodiments, specific building blocks may be selected and/or further functionalized such that a desired MOF structure with a predetermined pore size is obtained. Generally, the larger the molecular size of the at least one bidentate organic compound or other ligands, the larger the pore size of the MOF. Such porous MOF(s) of the present disclosure may also be selected such that when they are exposed to downhole conditions (such as, for example, temperature or pressure) or a downhole environment (such as for example, the surrounding chemicals and the phase thereof, including pH, ionic strength, temperature, pressure, etc.,), an effective amount of the target chemical entity for the desired downhole application is desorbed (or released) from the porous MOF(s).

[0061] In embodiments, the pore size of the porous MOF may be controlled by the choice of the suitable ligand and/or of the at least one bidentate organic compound, such that the average pore size is in a range of from about 0.1 nm to about 75 nm, or an average pore size in a range of from about 0.5 nm to about 10 nm, or an average pore size in a range of from about 1.0 nm to about 5 nm.

[0062] In embodiments, the pore volume of the unit cell of the MOF is uniform throughout the MOF, such that the distribution of pore volume across the entire MOF particle or composition is uniform and the pore size is monodisperse. For example, the MOFs used in the methods of present disclosure may be MOFs that contain a single pore size, such as a single pore size that falls in a range of from about 0.1 nm to about 75 nm, or a single pore size that falls in a range of from about 0.5 nm to about 10 nm, or a single pore size that falls in a range of from about 1.0 nm to about 5 nm.

[0063] In some embodiments, the MOF may contain a distribution of pore sizes. In such embodiments, the MOFs used in the methods of present disclosure may be MOFs in which more than 70% of the total MOF pore volume, such as more than 85%, or more than 99%, is formed by pores having a pore diameter less than 100 nm, such as less than 50 nm or less than 40 nm. In embodiments, no more than 5% of the total MOF pore volume, such as more than 2% of the total pore volume, or more than 0.5% of the total pore volume is formed by empty pores having a pore diameter greater than 50 nm, or greater than 100 nm or greater than 200 nm.

[0064] The porous MOFs suitable for use in the methods of the disclosure may comprise one or more of the following characteristics: a surface area (Langmuir surface area) of the plurality of pores is greater than about 500 m²/g; a surface area of the plurality of pores may be from about 500 to about 15,000 m²/g, or a surface area of the plurality of pores may be from about 1,000 to about 10,000 m²/g, or surface area of the plurality of pores may be from about 2,000 to about 6,000 m²/g; an average pore volume of the plurality of pores comprising the porous MOF is in the range from about 0.005 to about 15 cm³/g, such as from about 0.05 to about 5 cm³/g; and the framework of the porous MOF has a density in a range of from about 0.03 to about 5 g/cm³, or from about 0.3 to about 1.5 g/cm³.

[0065] In embodiments, the porous MOFs comprise a thermal stability range (in which it will not decompose, or less than 2% by mass deterioration or decomposition, such as less than 1% by mass deterioration or decomposition) of at least 10°C higher than the highest temperature that is observed in the subterranean formation being treated, such as a thermal stability range of at least up to 200°C, or a thermal stability range of greater than about 60°C to about 200°C, or a thermal stability range of greater than from about 80°C to about 190°C, or a thermal stability range of greater than from about 100°C to about 180°C. In embodiments, the porous MOFs may be selected to have chemical (and thermal) stability (in which it will not decompose, or less than 2% by mass deterioration or decomposition, such as less than 1% by mass deterioration or decomposition) that is sufficient to survive downhole chemical environments for periods greater than a week, such as periods greater than a month, or greater than 6 months. In embodiments, the porous MOFs may comprise a pressure stability range of at least 100 psi higher than the highest pressure that is observed in the subterranean formation being treated, such as a pressure stability range of greater than about 3,000 psi to about 25,000 psi, or a pressure stability range of greater than from about 4,000 psi to about 6,000 psi. In embodiments, the porous MOFs comprise a pH stability range of from about -1 to about 15, or a pH stability range of from about 5 to about 10, or a pH stability range of from about 6 to about 8.5. In embodiments, the porous MOFs may stable at a pH in the range of from about -1 to about 3, such as a pH in the range of from 0.1 to about 2. In embodiments, the porous MOFs may stable at a pH in the range of from about 9 to about 15, such as a pH in the range of from 10 to about 12. The porous MOFs may stable (for example, less than 2% by mass deterioration or decomposition, or less than 1% by mass deterioration or decomposition) at such pH values for periods greater than a week, such as periods greater than a month, or greater than 6 months.

[0066] In the methods of the present disclosure, the uptake of the target chemical entity into the porous MOF (to load the MOF with the target chemical entity) may occur by any suitable method and to any suitable extent. For example, in embodiments, the target chemical entity may be present in the loaded MOF or MOF system (such as composite MOFs, which may be coated with a polymer or inter-polymer complex) at a weight percent of from about 25% to about 1,000%) relative to the weight of the MOF alone, or about 60%> or about 300%, or about 80 to about 200% relative to the weight of the MOF alone.

[0067] The term "uptake" refers, for example, to a sorption process resulting in the association of a target chemical entity with a porous MOF, such as a porous MOF tailored to selectively associate with the functional groups of the target chemical entity. In embodiments, the uptake of the target chemical entity into the porous MOF, such as a porous MOF tailored to selectively associate with the functional groups of the target chemical entity, is reversible under predetermined conditions, such as downhole conditions and/or down hole environments, at least to the extent that an effective amount of the target chemical entity may be released downhole for the desired downhole application, such as, for example, as a crosslinker, a breaker, an acidizing agent (or acid), or base.

[0068] As used herein, "sorption" is a general term that refers, for example, to a process resulting in the association of a target chemical entity with a MOF and includes both adsorption and absorption. Absorption refers to a process in which ions, atoms or molecules of a target chemical entity move from the surrounding bulk phase (for example, a liquid) into the porous MOF material. Adsorption refers to a process in which ions, atoms or molecules of a target chemical entity move from a bulk phase (for example, solid or liquid) onto a surface of the MOF. The reverse of these processes transfers the target chemical entity back into a bulk phase or fluid such that it may act in its intended capacity, such as, for example, as a crosslinker, a breaker, or an acidizing agent.

[0069] The porous MOF(s) and/or composite MOF(s) of the present disclosure may be used for temporarily storing the target chemical entity for a predetermined amount of time, for example, while the target chemical entity is being transported downhole with the treatment fluid. In embodiments, the target chemical entity and MOF may be selected such that the target chemical entity may be temporarily stored in the MOF for a predetermined time after loading (such as minutes, hours, days or months), for example, from about 5 to about 2,000 minutes, such as from about 10 to about 1,000 minutes, or 20 to about 500 minutes, or from about 30 to about 120 minutes. Subsequently, after the predetermined amount of time has passed, the target chemical entity may be released from the porous MOF into the bulk of the treatment fluid, such as, for example, to act in its intended capacity as a crosslinker, a breaker, or an acidizing agent.

[0070] In some embodiments, after the loaded MOF has been exposed to a predetermined downhole condition, such as a temperature, pressure, pH, treatment fluid component

concentration, or combination thereof, the target chemical entity may be released from the pores of the porous MOF (in other words released from the MOF), into the bulk of the treatment fluid, such as, for example, to act in its intended capacity as a crosslinker, a breaker, or an acidizing agent. For example, in embodiments, the release mechanism of the target chemical entity from the MOF may be controlled through an outward diffusion process across the MOF 3D network in the bulk of the fluid, driven by a chemical potential difference between the bulk of the fluid and the interior of the MOF. In some embodiments, the diffusion process is accelerated by exposure of the loaded MOF to elevated temperatures.

[0071] The driving force of the release (outward diffusion) of the target chemical entity from the loaded MOF may depend on a number of factors. For example, in some embodiments, driving force of the release (outward diffusion) may be thermal, coupled by media pH, polymer film (hydration rate) thickness and so on. Each type of target chemical entity may have a distinguished set of threshold conditions for the release event to take place. For example, for a crosslinker, the process may happen at ambient temperature (slower rate of release). For a breaker, the minimum temperature of release may be controlled by the thermodynamics of the breaker species itself. Additionally, for a coated acid-loaded MOF or a coated base-loaded MOF (discussed below), which is coated with an inter-polymer complex (IPC), the main driving force of the release (modulation of the release rate) may involve the characteristics of the IPC.

[0072] In some embodiments, the MOF may be selected such that after the loaded MOF has been exposed to a predetermined downhole condition or downhole environment, such as a temperature, pressure, pH, treatment fluid component concentration, or combination thereof, the target chemical entity may be released from the porous MOF into the bulk of the treatment fluid, decomposition of MOF, such thermal decomposition and/or chemical decomposition, may be used to release of the target chemical entity into the bulk of the treatment fluid, such as, for example, to act in its intended capacity. [0073] In embodiments, loading the porous MOF with the target chemical entity may comprise soaking the porous MOF in a target chemical entity slurry or a solvent containing the target chemical entity, such as an organic solvent (for example, a volatile organic solvent), for a predetermined amount of time, such as for about 4 hours or more, or for about 24 hours or more. Optionally, the target chemical entity slurry or solvent containing the target chemical entity may be refreshed and the soaking period may be repeated until the porous MOF is sufficiently loaded with the target chemical entity thereby forming a loaded MOF, which optionally may be coated, such as with a polymer and/or an inter-polymer complex (IPC) to form a loaded MOF or loaded MOF system. In embodiments, the porous MOF may be optionally heated (with or without reduced pressure) at one or more temperatures before, during or after any of the above soaking periods to adjust (for example, increase or decrease) the amount of target chemical entity loaded in the porous MOF. In embodiments, the heating temperature may be selected based on the thermal properties of the porous MOF and the identity of the target chemical entity or solvent containing the target chemical entity.

[0074] The concentration of the target chemical entity (alone, not counting the weight of the MOF) in the treatment fluid may be varied depending on the identity of the target chemical entity and its intended function.

[0075] In embodiments, the porous MOF may optionally be activated prior to loading of any target chemical entity therein in order to empty the plurality of pores and remove any residual chemical species that may remain after formation of the MOF. In embodiments, activating the porous MOF may comprise soaking the MOF in a solvent, such as an organic solvent (for example, a volatile organic solvent), for a predetermined amount of time, such as for about 12 hours or more, or for about 24 hours or more. Optionally, the solvent may be refreshed and the soaking period may be repeated until the elution concentration of any residual species in the MOF immersed solvent is at a level of less than 10 ppm, such as less than 1 ppm, or less than 0.1 ppm. In embodiments, the porous MOF may be optionally heated (with or without reduced pressure) at one or more temperatures before, during or after any of the above soaking periods to aid in the removal of any residual chemical species that may remain after formation of the MOF. In embodiments, the heating temperature may be selected based on the thermal properties of the porous MOF and the identity of the soaking solvent. For example, generally MOFs may be heated to a temperature of 120°C for 12 hours, and then heated at 60°C for 12 hours at 10^~5 torr, without any degradation.

[0076] In embodiments, after the porous MOF is activated, the porous MOF may be loaded with a target chemical entity by any suitable method, such as those discussed above.

[0077] The storage capacity of the porous MOFs may be described in terms of the percentage of the available pore volume that is occupied by the target chemical entity. For example, when the maximum amount of target chemical entity is loaded into the available pore structure of the porous MOF, such that the porous MOF is occupied with a maximum amount of target chemical entity, then the MOF may be described as being at 100% filling or storage capacity. The maximum amount of target chemical entity that may be loaded into the MOF pore structure can be determined by measuring the mass change of a porous MOF upon its exposure to a particular target chemical entity for an predetermined amount of time and, after washing off the excess target chemical entity and drying the loaded MOF, calculating the corresponding mass of target chemical entity. Any degree of filling capacity may be selected for the porous MOFs of the present disclosure. In embodiments, a loaded porous MOF-target chemical entity (loaded MOF) may have a filling capacity in the range of from about 10% to about 100%, or about 60% or about 100%, or about 80 to about 95% relative to the maximum weight of the target chemical entity that may be loaded into the MOF.

[0078] In embodiments, the loaded MOF, such as a MOF loaded with a strong base or strong acid, may be distributed in a polymeric material, and/or coated in a polymeric material, to form a composite MOF, such as a composite MOF particle, which may be incorporated into a treatment fluid and pumped into a subterranean formation. In embodiments, composite MOFs may further delay the diffusion of the target chemical entity from the MOF to the bulk of the treatment fluid. Because the target chemical entity will diffuse out of the MOF and then out of the polymeric material, the amount of further delay can be increased by increasing the size of the polymer material particle into which the loaded MOF is dispersed and/or by increasing the depth of the layer of polymeric material coated on individual loaded MOFs. The amount of loaded MOF distributed in the polymeric material and/or the size of the polymer material particles will depend on the specific application for which the composite MOF is intended. [0079] Suitable solvents or use with the methods of the present disclosure, such as for preparing the various MOFs of the present disclosure, or for forming the treatment fluids disclosed herein, may be aqueous or organic based. Aqueous solvents may include at least one of fresh water, sea water, brine, mixtures of water and water-soluble organic compounds and mixtures thereof. Organic solvents may include any organic solvent that is able to dissolve or suspend the various components, such as reactants for forming the MOF and/or components of the treatment fluid.

[0080] Suitable organic solvents may include, for example, alcohols, glycols, esters, ketones, nitrites, amides, amines, cyclic ethers, glycol ethers, acetone, acetonitrile, benzene, 1- butanol, 2-butanol, 2-butanone, t-butyl alcohol, carbon tetrachloride, chlorobenzene, chloroform, cyclohexane, 1 ,2-dichloroethane, diethyl ether, diethylene glycol, diethylene glycol dimethyl ether, 1 ,2-dimethoxy-ethane (DME), dimethylether, dibutylether, dimethyl-formamide (DMF), dimethyl sulfoxide (DMSO), dioxane, ethanol, ethyl acetate, ethylene glycol, glycerin, heptanes, hexamethylphosphoramide (HMPA), hexamethylphosphorous triamide (HMPT), hexane, methanol, methyl t-butyl ether (MTBE), methylene chloride, N-methyl-2-pyrrolidinone (NMP), nitromethane, pentane , petroleum ether (ligroine), 1-propanol, 2-propanol, pyridine,

tetrahydrofuran (THF), toluene, triethyl amine, o-xylene, m-xylene, p-xylene, ethylene glycol monobutyl ether, polyglycol ethers, pyrrolidones, N-(alkyl or cycloalkyl)-2-pyrrolidones, N- alkyl piperidones, N, N-dialkyl alkanolamides, Ν,Ν,Ν',Ν'-tetra alkyl ureas, dialkylsulfoxides, pyridines, hexaalkylphosphoric triamides, l,3-dimethyl-2-imidazolidinone, nitroalkanes, nitrocompounds of aromatic hydrocarbons, sulfolanes, butyrolactones, alkylene carbonates, alkyl carbonates, N-(alkyl or cycloalkyl)-2 -pyrrolidones, pyridine and alkylpyridines, diethylether, dimethoxyethane, methyl formate, ethyl formate, methyl propionate, acetonitrile, benzonitrile, dimethylformamide, N-methylpyrrolidone, ethylene carbonate, dimethyl carbonate, propylene carbonate, diethyl carbonate, ethylmethyl carbonate, dibutyl carbonate, lactones, nitromethane, nitrobenzene sulfones, tetrahydrofuran, dioxane, dioxolane, methyltetrahydrofuran,

dimethylsulfone, tetramethylene sulfone, diesel oil, kerosene, paraffmic oil, crude oil, liquefied petroleum gas (LPG), mineral oil, biodiesel, vegetable oil, animal oil, aromatic petroleum cuts, terpenes, perchloroethylene, methylene chloride, mixtures thereof.

[0081] In some embodiments, a plurality of loaded MOFs, which may be loaded with the same or different target chemical entities, may be present in the treatment fluids of the present disclosure. For example, a plurality of loaded MOFs in the treatment fluid may comprise two or more MOFs (a first and a second loaded MOF, which may have different structures) loaded with the same target chemical entity (or different target chemical entities), where the first loaded MOF is selected such that it effectively releases the target chemical entity at a different rate and/or under different conditions than the second loaded MOF. For example, a plurality of loaded MOFs in the treatment fluid may be selected such that the respective target chemical entities may be released in multiple stages or at different times after being pumped into the subterranean formation, depending on when the target chemical entity is intended to perform its desired function. In embodiments, each of the active chemical components present in a treatment fluid may be present in one or more loaded MOFs. Such loaded MOFs may have different target chemical entity release kinetics that are selected to release the target chemical entity at the time the desired function is to be implemented.

[0082] While the methods and treatment fluids of the present disclosure are described herein as comprising the above-mentioned components, it should be understood that the methods and fluids of the present disclosure may optionally comprise other additional materials, such as the materials and additional components discussed below, which relate to various methods and applications using the MOFs, and/or MOF composites. As discussed in more detail below, after the respective target chemical entity diffuses and/or is released from the reversibly loaded MOF it may perform its intended function and/or application, for example, as a crosslinker, a breaker, or an acidizing agent.

[0083] MOFS AS A CROSSLINKER CARRIER

[0084] In some embodiments, the target chemical entity that is reversibly loaded into the porous MOF is a crosslinker and the methods of the present disclosure comprise introducing a crosslinkable fluid including a crosslinking composition and one or more crosslinkable components or materials into a subterranean formation. The extent to which this target chemical entity may be loaded into the MOF is discussed above.

[0085] In such embodiments, the treatment fluid of the present disclosure may be a crosslinking fluid and comprise a crosslinking composition and one or more crosslinkable components or materials. Such a treatment fluid may be employed in downhole applications, such as for crosslinking materials in subterranean formations, treating hydrocarbon-bearing rock formations, sealing hydrocarbon-bearing rock formations and/or controlling fluids in hydrocarbon-bearing rock formations to minimize flow of an unacceptable amount of material/fluid (such as water), into a predetermined area, such as into a wellbore, which can be referred to as fluid loss.

[0086] As used herein, the phrase "crosslinkable fluid," refers, for example, to a composition comprising a solvent, a crosslinkable material, which includes any crosslinkable compound and/or substance with a crosslinkable moiety, (hereinafter "crosslinkable component") that may be substantially inert to any produced fluids (gases and liquids) and other fluids injected into the wellbore or around the wellbore, such as workover fluids, and a crosslinking

composition which comprises a crosslinker, for example, to seal at least a portion of the area into which the crosslinkable fluid is pumped.

[0087] The crosslinkable fluid that may be used in such embodiments of the methods of the present disclosure may be a solution initially having a very low viscosity that can be readily pumped or otherwise handled. For example, the viscosity of the crosslinkable fluid may be from about 1 (centiPoise) cP to about 1,000 cP, or be from about 1 cP to about 100 cP at the treating temperature, which may range from a surface temperature to a bottom-hole static (reservoir) temperature (BHST), such as from about -40°C to about 150°C, or from about 10°C to about 70°C, or from about 25°C to about 60°C, or from about 32°C to about 55°C.

[0088] Crosslinking the crosslinkable fluid generally increases its viscosity. As such, having the composition in the uncrosslinked/unviscosified state allows for pumping of a relatively less viscous fluid having relatively low friction pressures within the well tubing, and the crosslinking may be delayed in a controllable manner such that the properties of thickened crosslinked fluid are available at the rock face instead of within the wellbore. Such a transition to a crosslinked/uncrosslinked state may be achieved over a period of minutes or hours or days based on the particular molecular make-up of the crosslinker loaded MOF system, and results in the initial viscosity of the crosslinkable fluid increasing by at least an order of magnitude, such as at least two orders of magnitude, or results in the initial viscosity of the crosslinkable fluid increasing from by at least two orders of magnitude at the treating temperature, for example, from less than about 100 centipoise at 100 sec^"1 sheer rate at the treating temperature to at least about 10000 centipoise at 100 sec^"1 at the treating temperature. [0089] In such embodiments, the at least one bidentate organic compound or ligands are selected to form a porous MOF having pores, cages and/or channels of a predetermined size and shape, such that the functional groups of the porous MOF(s) may be selected to non-covalently interact with the functional groups of a preselected crosslinker molecule. In embodiments, specific bidentate organic compounds or ligands may be selected and/or further functionalized such that functional groups line the cages and channels, and/or the pores. In embodiments, specific building blocks may be selected and/or further functionalized such that a desired MOF structure with a predetermined pore size is obtained. Such porous MOF(s) of the present disclosure may also be selected such that when they are exposed to downhole, and/or reservoir/fracture conditions, the crosslinker molecules are desorbed (or released) from the porous MOF(s).

[0090] In embodiments in which the target chemical entity is a crosslinker, the pore size of the porous MOF may be controlled by the choice of the suitable ligand and/or of the at least one bidentate organic compound, such that the average pore size is in a range of from about 0.2 nm to about 75 nm, or an average pore size in a range of from about 0.5 nm to about 10 nm, or an average pore size in a range of from about 1 nm to about 5 nm.

[0091] In embodiments, the pore volume of the unit cell of the MOF into which the crosslinker is loaded may be uniform throughout the MOF, such that the distribution of pore volume across the entire MOF particle or composition is uniform and the pore size is monodisperse. For example, the MOFs used in the methods of present disclosure may be MOFs that contain a single pore size, such as a single pore size that falls in a range of from about 0.1 nm to about 75 nm, or a single pore size that falls in a range of from about 0.5 nm to about 10 nm, or a single pore size that falls in a range of from about 1.0 nm to about 5 nm.

[0092] In some embodiments, the MOF into which the crosslinker is loaded may contain a distribution of pore sizes. In such embodiments, the MOFs used in the methods of present disclosure may be MOFs in which more than 70% of the total MOF pore volume, such as more than 85%, or more than 99%, is formed by pores having a pore diameter less than 100 nm, such as less than 50 nm or less than 40 nm. In embodiments, no more than 5% of the total MOF pore volume, such as more than 2% of the total pore volume, or more than 0.5% of the total pore volume is formed by pores having a pore diameter greater than 50 nm, or greater than 100 nm or greater than 200 nm.

[0093] In the methods of the present disclosure, the uptake of the crosslinker into the porous MOF (to load the MOF with crosslinker) may occur by any suitable method. In embodiments, the uptake of the crosslinker into the porous MOF, such as a porous MOF tailored to selectively associate with the functional groups of the crosslinker molecule, is reversible under predetermined conditions, such as various downhole conditions or downhole environments, or conditions that are created downhole conditions.

[0094] The MOFs may be selected such that under predetermined conditions the crosslinker atoms or molecules move from the surrounding bulk phase (for example, a liquid) into the porous MOF material (absorption) and/or move from a bulk phase (for example, solid or liquid) onto a surface of the MOF (adsorption). The reverse of these processes transfers the crosslinker back into a bulk phase or fluid such that it may interact or react with the crosslinkable component of the crosslinkable fluid.

[0095] The porous MOF(s) of the present disclosure may be used for temporarily storing the crosslinker for a predetermined amount of time, for example, while the crosslinker is being transported downhole with the well treatment fluid. In embodiments, the crosslinker and MOF system may be selected such that the crosslinker may be temporarily stored in the MOFs for a predetermined time after loading (such as minutes, hours or days), for example, from about 5 to about 2,000 minutes, such as from about 10 to about 1,000 minutes, or 20 to about 500 minutes, or from about 30 to about 120 minutes. Subsequently, after the predetermined amount of time has passed, the crosslinker may be released from the porous MOF into the bulk of the

crosslinkable fluid, such as, for example, to initiate the crosslinking of a polymer contained therein and/or otherwise act in its intended capacity as a crosslinker.

[0096] In some embodiments, after the crosslinker loaded MOF has been exposed to a predetermined downhole condition, such as a temperature, pressure, pH, treatment fluid component concentration, or combination thereof, the crosslinker may be released from the porous MOF into the bulk of the crosslinkable fluid, such as, for example, to initiate the crosslinking of the polymer contained therein and/or otherwise act in its intended capacity as a crosslinker. For example, in embodiments, the release mechanism of the crosslinker from the MOF may be controlled through an outward diffusion process across the MOF 3D network in the bulk of the fluid, driven by a chemical potential difference between the bulk of the fluid and the interior of the MOF. In some embodiments, the diffusion process is accelerated by exposure of the loaded MOF to elevated temperatures.

[0097] In embodiments, the crosslinker molecules are present in the loaded MOF at a weight percent of from about 25% to about 1,000% relative to the weight of the MOF alone (without any crosslinker present), or about 60%> or about 300%, or about 80 to about 200% relative to the weight of the MOF alone.

[0098] The porous MOFs suitable for use in the methods of the disclosure may comprise one or more of the following characteristics: a surface area (Langmuir surface area) of the plurality of pores is greater than about 500 m²/g; a surface area of the plurality of pores may be from about 500 to about 15,000 m²/g, or a surface area of the plurality of pores may be from about 1,000 to about 10,000 m²/g, or surface area of the plurality of pores may be from about 2,000 to about 6,000 m²/g; a surface area of the plurality of pores is about 800 to about 10,000 m²/g; an average pore volume of the plurality of pores comprising the porous MOF is in the range from about 0.005 to about 15 cm³/g, such as from about 0.05 to about 5 cm³/g; and the framework of the porous MOF may have a density in a range of from about 0.03 to about 1 g/cm³, or from about 0.3 to about 0.9 g/cm³.

[0099] In embodiments, the porous MOFs comprise a thermal stability range (in which it will not decompose, or less than 2% by mass deterioration or decomposition, such as less than 1% by mass deterioration or decomposition) of at least 50°C higher than to the highest temperature that is observed in the subterranean formation being treated, such as a thermal stability range of at least up to 200°C, or a thermal stability range of greater than about 60°C to about 200°C, or a thermal stability range of greater than from about 80°C to about 190°C, or a thermal stability range of greater than from about 100°C to about 180°C. In embodiments, the porous MOFs may be selected to have chemical (and thermal) stability (in which it will not decompose, or less than 2% by mass deterioration or decomposition, such as less than 1% by mass deterioration or decomposition) that is sufficient to survive downhole chemical

environments. In embodiments, the porous MOFs comprise a pressure stability range of at least 100 psi higher than the highest pressure that is observed in the subterranean formation being treated, such as a pressure stability range of greater than about 3,000 psi to about 25,000 psi, or a pressure stability range of greater than from about 4,000 psi to about 6,000 psi. In embodiments, the porous MOFs comprise a pH stability range of from about 2 to about 12, or a pH stability range of from about 5 to about 9, or a pH stability range of from about 6 to about 8.5. In embodiments, the porous MOFs, such as base-loaded MOFs, may stable at a pH in the range of from about 9 to about 15, such as a pH in the range of from 10 to about 12.

[00100] Any crosslinker or crosslinking agent that can reversibly associate with the MOF may be loaded into the MOF. "Crosslinker" and/or the phrase "crosslinking agent" (hereinafter collectively referred to as crosslinkers) refer, for example, to a compound or mixture that assists in the formation of a three-dimensional polymerized structure of the crosslinkable component under at least some downhole conditions. In embodiments, loading the porous MOF with the crosslinker may comprise soaking the MOF in a crosslinker slurry or solvent containing the crosslinker, such as an organic solvent (for example, a volatile organic solvent), for a

predetermined amount of time, such as for about 4 hours or more, or for about 24 hours or more. Optionally, the crosslinker slurry or solvent containing the crosslinker may be refreshed and the soaking period may be repeated until the MOF is sufficiently loaded with crosslinker. In embodiments, the porous MOF may be optionally heated (with or without reduced pressure) at one or more temperatures before, during or after any of the above soaking periods to adjust (for example, increase or decrease) the amount of crosslinker loaded in the porous MOF. In embodiments, the heating temperature may be selected based on the thermal properties of the porous MOF and the identity of the soaking crosslinker slurry or solvent containing the crosslinker.

[00101] In embodiments, the porous MOF may optionally be activated prior to loading of any crosslinker therein in order to empty the plurality of pores and remove any residual chemical species that may remain after formation of the MOF. In embodiments, activating the porous MOF may comprise soaking the MOF in a solvent, such as an organic solvent (for example, a volatile organic solvent), for a predetermined amount of time, such as for about 12 hours or more, or for about 24 hours or more. Optionally, the solvent may be refreshed and the soaking period may be repeated until the elution concentration of any residual species in the solvent that the MOF is immersed in is at a level of less than 10 ppm, such as less than 1 ppm, or less than 0.1 ppm. In embodiments, the porous MOF may be optionally heated (with or without reduced pressure) at one or more temperatures before, during or after any of the above soaking periods to aid in the removal of any residual chemical species that may remain after formation of the MOF. In embodiments, the heating temperature for activating the may be selected based on the thermal properties of the porous MOF and the identity of the soaking solvent. For example, some MOFs may be activated by heating the MOF sample to a temperature 120°C for 12 hours, and then heated at 60°C for 12 hours at 10^~5 torr, without any degradation.

[00102] In embodiments, after the porous MOF is activated, the porous MOF may be loaded with a crosslinker by any suitable method, such as those discussed above.

[00103] Suitable crosslinkers for incorporation into the MOF in the methods of the present disclosure are those capable of crosslinking polymer molecules to form a three-dimensional network. Suitable organic crosslinking agents include, but are not limited to, aldehydes, dialdehydes, phenols, substituted phenols, and ethers. Suitable inorganic crosslinking agents include, but are not limited to, polyvalent metals, conventional chelated polyvalent metals, and compounds capable of yielding polyvalent metals. In embodiments, the crosslinkers may be Group 4 (of the periodic table) based crosslinkers, such as the titanates or zirconates, or Group 13 (of the periodic table) based crosslinkers, such as borates or aluminates. For example, such crosslinkers may comprise a chemical compound containing a polyvalent ion such as boron or a metal such as chromium, iron, aluminum, titanium, antimony and zirconium, or mixtures of polyvalent ions. Suitable boron crosslinkers include boric acid, sodium tetraborate, and encapsulated borates. Suitable zirconium crosslinkers include zirconium complexes, such as lactates (for example sodium zirconium lactate), triethanolamines, 2,2'-iminodiethanol, amino acids, and with mixtures of these ligands. Suitable titanates include lactates and

triethanolamines, and mixtures thereof. Suitable crosslinkers also include aluminum, iron and/or titanium containing species.

[00104] The concentration of the crosslinker (alone, not counting the weight of the MOF) in the crosslinkable fluid may be from about 0.001 wt % to about 10 wt %, such as about 0.005 wt % to about 2 wt %, or about 0.01 wt % to about 1 wt %.

[00105] In embodiments, the crosslinkers may be those containing at least one functional group having a high affinity for the one or more sites in the plurality of pores in the MOF. In embodiments, the at least one bidentate organic compound or one or more of the other ligands may be functionalized in order to create sites with a desired functionality. This ability of MOFs to be functionalized is useful because the pores may be lined with a high concentration of ordered sites whose properties, such as hydrophobic, hydrophilic, polar, non-polar, and/or steric properties, can be tailored to match the functionality of the crosslinker molecule and thereby allow for the tuning of the MOF/crosslinker system to achieve the desired diffusion/release rates of the crosslinker from the MOF.

[00106] The storage capacity of the porous MOFs may be described in terms of the percentage of the available pore volume that is occupied by crosslinkers. For example, when the maximum amount of crosslinker is loaded into the available pore structure of a porous MOF, such that the porous MOF is occupied with a maximum amount of crosslinker molecules or crosslinking agents, then the MOF may be described as being at 100% filled, loaded or at storage capacity. The maximum amount of crosslinker molecules that may be loaded into the MOF pore structure can be determined by measuring the mass change of a porous MOF upon its exposure to a crosslinker or crosslinking agent for an predetermined amount of time and, after washing off the excess crosslinker and drying the loaded MOF, calculating the corresponding mass of crosslinker. Any degree of filling capacity may be selected for the porous MOFs of the present disclosure. In embodiments, a loaded porous MOF-crosslinker system may have a filling capacity in the range of from about 10% to about 100%, or about 60% or about 100%, or about 80 to about 95% relative to the maximum weight of the crosslinker or crosslinking agent that may be loaded into the MOF.

[00107] In embodiments, a loaded porous MOF-crosslinker system may be present in the crosslinkable fluid, which may comprise a solvent and a crosslinkable material, in an amount of from about 0.2 to about 50 pounds per thousand gallons of the crosslinkable fluid, such as from about 0.5 to about 20 pounds per thousand gallons of the fluid, or from about 1.0 to about 15 pounds per thousand gallons of the fluid.

[00108] Suitable solvents for use with the crosslinkable fluid in the present disclosure may be aqueous or organic-based, and include those mentioned above in addition to those mentioned below. Briefly, aqueous solvents may include at least one of fresh water, sea water, brine, mixtures of water and water-soluble organic compounds and mixtures thereof. Organic solvents may include any organic solvent that is able to dissolve or suspend the various components of the crosslinkable fluid, such as any of those identified above and throughout the present disclosure.

[00109] In some embodiments, the crosslinkable fluid may initially have a viscosity similar to that of the aqueous solvent, such as water. An initial water-like viscosity may allow the solution to effectively penetrate voids, small pores, and crevices, such as encountered in fine sands, coarse silts, and other formations. In other embodiments, the viscosity may be varied to obtain a desired degree of flow sufficient for decreasing the flow of water through, or increasing the load-bearing capacity of, a formation. The viscosity of the crosslinkable fluid may also be varied by increasing or decreasing the amount of solvent relative to other components, or by other techniques, such as by employing viscosifying agents.

[00110] The crosslinkable fluids or compositions suitable for use in the methods of the present disclosure comprise a crosslinkable component. As discussed above, a "crosslinkable component," as the term is used herein, is a compound and/or substance that comprises a crosslinkable moiety. For example, the crosslinkable components may contain one or more crosslinkable moieties, such as a carboxylate and/or a cis-hydroxyl (vicinal hydroxyl) moiety, that is able to coordinate with the reactive sites of known crosslinkers, such as known

crosslinkers that may be loaded into MOFs.

[00111] The crosslinkable component may be natural or synthetic polymers (or derivatives thereof) that comprise a crosslinkable moiety, for example, substituted galactomannans, guar gums, high-molecular weight polysaccharides composed of mannose and galactose sugars, or guar derivatives, such as hydrophobically modified guars, guar-containing compounds, and synthetic polymers. Suitable crosslinkable components may comprise a guar gum, a locust bean gum, a tara gum, a honey locust gum, a tamarind gum, a karaya gum, an arabic gum, a ghatti gum, a tragacanth gum, a carrageenen, a succinoglycan, a xanthan, a diutan, a hydroxylethylguar hydroxypropyl guar, a carboxymethylhydroxyethyl guar, a carboxymethylhydroxypropylguar, an alkylcarboxyalkyl cellulose, an alkyl cellulose, an alkylhydroxyalkyl cellulose, a carboxylalkyl cellulose, a carboxyalkyl cellulose ether, a hydroxyethylcellulose, a carboxymethylhydroxyethyl cellulose, a carboxymethyl starch, a copolymer of 2-acrylamido-2methyl-propane sulfonic acid and acrylamide, a terpolymer of 2-acrylamido-2methyl-propane sulfonic acid, acrylic acid, acrylamide, or derivative thereof. In embodiments, the crosslinkable components may be present at about 0.01% to about 4.0% by weight based on the total weight of the crosslinkable fluid, such as at about 0.10% to about 2.0% by weight based on the total weight of the crosslinkable fluid.

[00112] The term "derivative" herein refers, for example, to compounds that are derived from another compound and maintain the same general structure as the compound from which they are derived.

[00113] Upon selection of the appropriate crosslinkable component (for example, in view of factors such as the downhole environment and/or desired application) to be incorporated into the crosslinkable fluid (or treatment fluid), crosslinking may be accomplished through the assistance of a crosslinking composition comprising a loaded MOF, such as a crosslinker-loaded MOF.

[00114] For example, when the particular application may include the formation of borate-crosslinked gels, a suitable crosslinkable component may include galactomannan polymers, such as guar and/or substituted guars, which crosslink when (1) the crosslinkable fluid (or treatment fluid) comprises boric acid, and (2) the pH is above about 8, where the borate ion exists and is available to crosslink and cause gelling. The methods of the present disclosure may be used to create such a borate-crosslinked gel in a variety of ways, such as by including one or more loaded MOFs in the crosslinkable fluid (or treatment fluid). For example, the crosslinkable fluid (or treatment fluid) for forming a borate-crosslinked gel may comprise a loaded MOF where the target chemical entity loaded into the MOF may be either boric acid or a pH control agent, such as a base, sodium hydroxide, magnesium oxide, sodium sesquicarbonate, and sodium carbonate, amines (such as hydroxyalkyl amines, anilines, pyridines, pyrimidines, quinolines, and pyrrolidines, and carboxylates such as acetates and oxalates).

[00115] In embodiments where the MOF is loaded with a base, such as sodium hydroxide, and the boric acid is in the bulk treatment fluid, the pH of the treatment fluid will increase as the base diffuses from and/or is released from the MOF and thus increase the effective concentration of the active crosslinker (the borate anion), which reversibly creates the borate crosslinks between the selected crosslinkable component, such as guar and/or substituted guars.

[00116] In some embodiments, delayed crosslinking may be achieved, for example, when the borate -based crosslinker is blended as an additive with the treatment fluid while MOF loaded with NaOH is co-pumped as the pH adjuster. In such embodiments, the event of crosslinking would begin when sufficient NaOH has been released into the bulk of the fluid and the pH of the fluid is raised above a predetermined known threshold value that is sufficient to initiate crosslinking.

[00117] In some embodiments, guar powder (that has not been subject to hydration) may be pumped into the wellbore along with a base-loaded MOF. In such embodiments, the base- loaded MOF may be selected such that the base (such as NaOH) is released in two stages) and/or two different base-loaded MOFs may be used that have different base release kinetics. In such embodiments, the guar powder may be hydrated downhole with the initial first stage release of base, such as NaOH, from base-loaded MOF/NaOH, which would raise the pH to moderate alkaline level sufficient to hydrate the guar. Subsequently, the full crosslinking of the guar may be initiated with the full (second stage) release of NaOH from the base loaded MOF to achieve a strongly alkaline treatment fluid that this able to fully crosslink the crosslinkable component (such as guar) of the treatment fluid.

[00118] In such embodiments, the "base-loaded" MOF may be present in the crosslinkable fluid (or treatment fluid) in a sufficient amount to result in a fluid pH (in the treatment zone of interest) above about 8, where the borate ion exists and is available to crosslink and cause gelling, such as a pH in the range of from about 8 to about 11 , or a pH in the range of from about 8 to about 9. At lower pH, the borate functional group is tied up by hydrogen and thus is not available for crosslinking. In embodiments where the MOF is loaded with boric acid, the bulk crosslinkable fluid (or treatment fluid) may be adjusted to a pH above 8 and as the boric acid diffuses from and/or is released from the MOF, the borate ion would then be available to crosslink and cause gelling in the bulk crosslinkable fluid (or treatment fluid).

[00119] In embodiments, the loaded MOF, such as a MOF loaded with a strong base, like sodium hydroxide, may be distributed in a polymeric material, and/or coated in a polymeric material, to form a composite MOF. In embodiments, composite MOFs may further delay the diffusion of the target chemical entity from the MOF to the bulk of the treatment fluid. Because the target chemical entity will diffuse out of the MOF and then out of the polymeric material, the amount of further delay can be increased by increasing the size of the polymer material particle into which the loaded MOF is dispersed and/or by increasing the depth of the layer of polymeric material coated on individual loaded MOFs. The effective amount of loaded MOF distributed in the polymeric material and/or the size of the polymer material particles will depend on the specific application for which the composite MOF is intended.

[00120] In embodiments, the polymeric material of the composite MOF may be a polymer material that is known to be stable to exposure to strong bases, and may be a material such as a gel and/or inter-polymer complex (IPC) comprising polyacrylamide (greater than 1%) crosslinked by a non-metallic crosslinker, as described in U.S. Patent Application Publication No. 2012/0138294, the disclosure of which is hereby incorporated by reference in its entirety.

[00121] As used herein, the term "gel" refers to a solid or semi-solid, jelly-like

composition that can have properties ranging from soft and weak to hard and tough. The term "gel" may also refer to a substantially dilute crosslinked system, which exhibits no flow when in the steady-state, which by weight is mostly liquid, yet behaves like solids due to a three- dimensional crosslinked network within the liquid. The crosslinks within the fluid may give a gel its structure (hardness) and contribute to stickiness. Accordingly, gels are a dispersion of molecules of a liquid within a solid in which the solid is the continuous phase and the liquid is the discontinuous phase. In an embodiment, a gel is considered to be present when the Elastic Modulus G' is larger than the Viscous Modulus G", when measured using an oscillatory shear rheometer (such as a Bohlin CVO 50) at a frequency of 1 Hz and at 20° C. The measurement of these moduli is well known to one of minimal skill in the art, and is described in An Introduction to Rheology, by H. A. Barnes, J. F. Hutton, and K. Walters, Elsevier, Amsterdam (1997), the disclosure of which is hereby incorporated by reference in its entirety.

[00122] As discussed in U.S. Patent Application Publication No. 2012/0138294, the term polyacrylamide refers to pure polyacrylamide homopolymer or copolymer with near zero amount of acrylate groups, a partially hydrolyzed polyacrylamide (PHP A) polymer or copolymer with a mixture of acrylate groups and acrylamide groups formed by hydrolysis and copolymers comprising acrylamide, acrylic acid, and/or other monomers. Hydrolysis of acrylamide to acrylic acid proceeds with elevated temperatures and is enhanced by acidic or basic conditions. The reaction product is ammonia, which will increase the pH of acidic or neutral solutions.

Except for severe conditions, hydrolysis of polyacrylamide tends to stop near 66%, representing the point where each acrylamide is sandwiched between two acrylate groups and steric hindrance restricts further hydrolysis. Polyacrylic acid is formed from acrylate monomer and is equivalent to 100% hydro lyzed polyacrylamide.

[00123] In embodiments, the polyacrylamide may have a weight average molecular weight of greater than or equal to about 0.5 million g/mol, or the polyacrylamide may have a weight average molecular weight of from about 1 million to about 20 million g/mol. The polyacrylamide may be a partially hydro lyzed polyacrylamide having a degree of hydrolysis of from 0 or 0.01% up to less than or equal to about 40%>, or from 0 or 0.05%> up to less than or equal to about 20%>, or from 0 or 0.1 % up to less than or equal to about 50%>.

[00124] The gel in which the base-loaded MOFs are dispersed may also comprise polyacrylamide crosslinked with a non-metallic crosslinker wherein the polyacrylamide is present in the gel at a concentration of greater than or equal to about 1 wt%, or greater than or equal to about 2 wt% and less than or equal to about 10 wt%, based on the total weight of the gel. In embodiments, such a gel has a pH of less than or equal to about 3 or greater than or equal to about 9, wherein the gel pH is defined as the pH of a 5% combination of the gel in water.

[00125] When the non-metallic crosslinker is a polylactam, such as polyvinylpyrrolidone

(PVP), the crosslinking appears to result from a ring-opening event wherein the lactam ring is opened to produce a bond between an acrylamide or acrylate moiety and the lactam moiety to produce the gel. For example, partially hydrolyzed polyacrylamide (PHP A) at 3% and polyvinylpyrrolidone (PVP) at 3-6% forms a very elastic gel when heated.

[00126] Such composite MOFs dispersed and/or coated in a gel and/or inter-polymer complex (IPC) comprising polyacrylamide (greater than 1%) crosslinked by a non-metallic crosslinker, as described in U.S. Patent Application Publication No. 2012/0138294, may be dehydrated to produce a composite MOF in which a gel concentrate coats the loaded MOF or a composite MOF that is a gel concentrate comprising loaded MOFs dispersed therein. The size of the gel concentrate may be selected to be any desirable size most suitable for the intended application of the composite MOF.

[00127] In embodiments, dehydrating the composite MOF comprises heating, freeze drying, or otherwise dehydrating the gel to produce the gel concentrate. In an embodiment, the particle size of the composite MOF may be reduced to facilitate subsequent rehydration and thus reconstitution of the gel concentration to produce a reconstituted composite MOF. [00128] As used herein, the term "dehydrating" as in "dehydrating a gel" refers to removing water or whatever solvent is present in the gel. Dehydrating may be accomplished by the application of heat, freeze, reduced pressure, freeze-drying, or any combination thereof.

[00129] As used herein, the term "freeze-drying" refers to the process also known in the art as lyophilisation, lyophilization or cryodesiccation, which is a dehydration process in which the temperature of a material is lowered (for example, freezing the material) and then

surrounding pressure is reduced to allow the frozen water in the material to sublimate directly from the solid phase to the gas phase.

[00130] In embodiments, the gel of the composite MOF, the gel being produced according to U.S. Patent Application Publication No. 2012/0138294, absorbs water when placed in contact with an aqueous solution. In embodiments, the gel of the composite MOF in contact with water uptakes greater than or equal to about 100% by weight of water, or greater than or equal to about 200% by weight of water, based on the weight of the gel present.

[00131] In embodiments, the gel of the composite MOF is formed at a pH of greater than or equal to about 9 and remains as a gel when the pH of the gel is lowered below 9, or when the pH of the gel is lowered below about 7, below about 5, and/or below about 3. Accordingly, in embodiments, the gels of the composite MOF are non-reversible once formed, pH stable once formed, or a combination thereof.

[00132] In embodiments, crosslinking may be accomplished in a crosslinkable fluid (or treatment fluid) comprising two or more MOFs, which optionally may be composite MOFs, each loaded with the same or different target chemical entities. For example, with respect to the above mentioned borate-crosslinked gel, the treatment fluid may comprise a first loaded MOF that is loaded with a pH control agent, such as a base, and a second loaded MOF that is loaded with boric acid. In such embodiment, the MOFs may be selected such that the pH control agent and the boric acid begin to diffuse from the respectively loaded MOF at any desired time, such as approximately the same time, independent of the other.

[00133] In embodiments, as result of the choice of the MOF crosslinker system, the rate of crosslinking may be retarded or delayed such that a gelled fluid may be readily pumped into a wellbore for entry into a subterranean formation before substantial crosslinking occurs in the crosslinkable fluid. One of ordinary skill in the art would appreciate that additional additives may be included in the crosslinkable fluid to provide additional delay before substantial crosslinking occurs in the crosslinkable fluid.

[00134] In embodiments, once the crosslinkable fluid containing the crosslinker-loaded

MOF is mixed, substantial crosslinking does not occur in the crosslinkable fluid immediately, such as for at least about 30 minutes, or substantial crosslinking does not occur in the

crosslinkable fluid for at least about 30 minutes to about 2 days. In some embodiments, substantial crosslinking does not occur in the crosslinkable fluid for at least about two hours, or substantial crosslinking does not occur in the crosslinkable fluid for at least about six hours to about 2 days. In some embodiments, substantial crosslinking does not occur in the crosslinkable fluid for at least about several days. The phrase "substantial crosslinking does not occur" means that at least 80% of the crosslinkable component remains uncrosslinked once the crosslinkable fluid is mixed (either downhole or at the surface), such as at least 95%, or as at least 99% of the crosslinkable component remains uncrosslinked once the crosslinkable fluid is mixed.

[00135] The crosslinkable fluid of the present disclosure may be tailored by selecting an appropriate loaded MOF (such as a crosslinker-loaded MOF where the diffusion of the crosslinker from the MOF is delayed) and optionally other additives such that the crosslinking occurs over a desired time interval. For example, the components of the crosslinkable fluid and/or the conditions the crosslinkable fluid is exposed to may be selected such that the crosslinking occurs in less than about 6 hours after release of the crosslinker from the MOF, or less than about 2 hours after release of the crosslinker from the MOF, or less than about 0.5 hours after release of the crosslinker from the MOF. In embodiments, the MOFs loaded with the target chemical entity, such as a crosslinker-loaded MOF, may be stored and/or for a few hours, weeks or even months, such as over six months, before being introduced into a subterranean formation.

[00136] Additionally, the components of the crosslinkable fluid and/or the conditions the crosslinkable fluid is exposed to may be selected such that the doubling of the apparent viscosity of the crosslinkable fluid may occur over about 0.5 hours to a few weeks, such as over two hours to several days. The components of the crosslinkable fluid and/or the conditions to which the crosslinkable fluid is exposed may also be selected such that the apparent viscosity increases to about 50 percent of its ultimate value upon mixing of the components and or exposure to the predetermined conditions for about 0.5 hours to several days at room temperature.

[00137] While the treatment fluids of the present disclosure are described herein as comprising the above-mentioned components, it should be understood that the crosslinkable fluids of the present disclosure may optionally comprise other chemically different materials, such as other additives and chemicals that are known to be commonly used in oilfield applications by those skilled in the art.

[00138] In this regard, the crosslinkable fluid may include components independently selected from any solids, liquids, gases, and combinations thereof, such as slurries, gas-saturated or non-gas-saturated liquids, mixtures of two or more miscible or immiscible liquids, and the like, as long as such additional components allow for the formation of a three-dimensional structure upon substantial completion of the crosslinking reaction. For example, the

crosslinkable fluid may comprise organic chemicals, inorganic chemicals, and any combinations thereof, which may be loaded into a MOF. Organic chemicals may be monomeric, oligomeric, polymeric, crosslinked, and combinations, while polymers may be thermoplastic, thermosetting, moisture setting, elastomeric, and the like. Inorganic chemicals may be metals, alkaline and alkaline earth chemicals, minerals, and the like.

[00139] In embodiments, the crosslinkable fluids of the present disclosure may comprise a breaker, which optionally may be loaded in a MOF (as discussed in more detail below) and released after the crosslinking event has occurred. Breakers that may be used in the methods of the present disclosure are discussed in more detail below.

[00140] Embodiments may also include proppant particles in the treatment fluid that are substantially insoluble in the fluids of the treatment formation. Proppant particles carried by the treatment fluid remain in the fracture created, thus propping open the fracture when the fracturing pressure is released and the well is put into production. Suitable proppant materials include, but are not limited to, sand, walnut shells, sintered bauxite, glass beads, ceramic materials, naturally occurring materials, or similar materials. Mixtures of proppants can be used as well. If sand is used, it may be from about 20 to about 100 U.S. Standard Mesh in size. With synthetic proppants, mesh sizes about 8 or greater may be used. Naturally occurring materials may be underived and/or unprocessed naturally occurring materials, as well as materials based on naturally occurring materials that have been processed and/or derived. Suitable examples of naturally occurring particulate materials for use as proppants include: ground or crushed shells of nuts such as walnut, coconut, pecan, almond, ivory nut, brazil nut, etc.; ground or crushed seed shells (including fruit pits) of seeds of fruits such as plum, olive, peach, cherry, apricot, etc.; ground or crushed seed shells of other plants such as maize (for example, corn cobs or corn kernels); processed wood materials such as those derived from woods such as oak, hickory, walnut, poplar, mahogany, etc. including such woods that have been processed by grinding, chipping, or other form of particulation, processing, etc. Further information on nuts and composition thereof may be found in ENCYCLOPEDIA OF CHEMICAL TECHNOLOGY, Edited by Raymond E. Kirk and Donald F. Othmer, Third Edition, John Wiley & Sons, vol. 16, pp. 248- 273, (1981).

[00141] The concentration of proppant in the treatment fluid or crosslinkable fluid can be at any concentration known in the art. For example, the concentration of proppant in the fluid may be in the range of from about 0.03 to about 3 kilograms of proppant added per liter of liquid phase. Also, any of the proppant particles can further be coated with a resin to potentially improve the strength, clustering ability, and flow back properties of the proppant.

[00142] Furthermore, the crosslinkable fluid may comprise buffers, pH control agents, and various other additives added to promote the stability or the functionality of the fluid. Any of these additional components may be loaded into a MOF for introduction into the subterranean formation. The components of the crosslinkable fluid may also be selected such that they may or may not react with the subterranean formation that is to be sealed and/or the other components of the treatment fluid (crosslinkable fluid).

[00143] The crosslinkable fluid may be based on an aqueous or non-aqueous solution.

The crosslinkable fluid may also comprise a mixture of various other crosslinking agents, and/or other additives, such as fibers or fillers, provided that the other components chosen for the mixture are compatible with the intended use of forming a crosslinked three-dimensional structure that at least increases the viscosity of the fluid and/or partially seals a portion of a subterranean formation, such as a water bearing portion of a subterranean formation, permeated by the crosslinkable fluid. When used in the crosslinkable fluids, the fiber of filler component may be included at concentrations from about 1 to about 15 grams per liter of the liquid phase of the crosslinkable fluid, such as a concentration of fibers or fillers from about 2 to about 12 grams per liter of crosslinkable fluid, or from about 2 to about 10 grams per liter of crosslinkable fluid.

[00144] Stabilizing agents can be added to the treatment fluid to slow the degradation of the crosslinked structure after its formation downhole. Suitable stabilizing agents may include buffering agents, such as agents capable of buffering at pH of about 8.0 or greater (such as water-soluble bicarbonate salts, carbonate salts, phosphate salts, or mixtures thereof, among others); and chelating agents (such as ethylenediaminetetraacetic acid (EDTA), nitrilotriacetic acid (NTA), or diethylenetriaminepentaacetic acid (DTP A),

hydroxyethylethylenediaminetriacetic acid (HEDTA), or hydroxyethyliminodiacetic acid (HEIDA), among others). Buffering agents may be added to the crosslinkable fluid in an amount from about 0.05 wt % to about 10 wt %, and from about 0.1 wt % to about 2 wt %, based upon the total weight of the crosslinkable fluid. Additional chelating agents may be added to the crosslinkable fluid to at least about 0.75 mole per mole of metal ions expected to be encountered in the downhole environment, such as at least about 0.9 mole per mole of metal ions, based upon the total weight of the crosslinkable fluid.

[00145] Surfactants can be added to promote dispersion or emulsification of components of the crosslinkable fluid, or to provide foaming of the crosslinked component upon its formation downhole. Suitable surfactants include alkyl polyethylene oxide sulfates, alkyl alkylolamine sulfates, modified ether alcohol sulfate sodium salts, or sodium lauryl sulfate, among others. Any surfactant which aids the dispersion and/or stabilization of a gas component in the fluid to form an energized fluid can be used. Viscoelastic surfactants, such as those described in U.S. Patents Nos. 6,703,352, 6,239,183, 6,506,710, 7,303,018 and 6,482,866, each of which are incorporated by reference herein in their entirety, are also suitable for use in fluids in some embodiments. Examples of suitable surfactants also include, but are not limited to, amphoteric surfactants or zwitterionic surfactants. Alkyl betaines, alkyl amido betaines, alkyl imidazolines, alkyl amine oxides and alkyl quaternary ammonium carboxylates are some examples of zwitterionic surfactants. An example of a useful surfactant is the amphoteric alkyl amine contained in the surfactant solution AQUAT 944 (available from Baker Petrolite of Sugar Land, Texas). A surfactant may be added to the crosslinkable fluid in an amount in the range of about 0.01 wt % to about 10 wt %, such as about 0.1 wt % to about 2 wt %. [00146] Charge screening surfactants may be employed. In some embodiments, the anionic surfactants such as alkyl carboxylates, alkyl ether carboxylates, alkyl sulfates, alkyl ether sulfates, alkyl sulfonates, a-olefin sulfonates, alkyl ether sulfates, alkyl phosphates and alkyl ether phosphates may be used. Anionic surfactants have a negatively charged moiety and a hydrophobic or aliphatic tail, and can be used to charge screen cationic polymers. Examples of suitable ionic surfactants also include, but are not limited to, cationic surfactants such as alkyl amines, alkyl diamines, alkyl ether amines, alkyl quaternary ammonium, dialkyl quaternary ammonium and ester quaternary ammonium compounds. Cationic surfactants have a positively charged moiety and a hydrophobic or aliphatic tail, and can be used to charge screen anionic polymers such as CMHPG.

[00147] In other embodiments, the surfactant is a blend of two or more of the surfactants described above, or a blend of any of the surfactant or surfactants described above with one or more nonionic surfactants. Examples of suitable nonionic surfactants include, but are not limited to, alkyl alcohol ethoxylates, alkyl phenol ethoxylates, alkyl acid ethoxylates, alkyl amine ethoxylates, sorbitan alkanoates and ethoxylated sorbitan alkanoates. Any effective amount of surfactant or blend of surfactants may be used in aqueous energized fluids.

[00148] Friction reducers may also be added to the crosslinkable fluid. Any suitable friction reducer polymer, such as polyacrylamide and copolymers, partially hydrolyzed polyacrylamide (at a concentration of less than 0.01% by weight), poly(2-acrylamido-2-methyl- 1 -propane sulfonic acid) (poly AMPS), and polyethylene oxide, may be used. Commercial drag reducing chemicals such as those sold by Conoco Inc. under the trademark "CDR" as described in U.S. Patent No. 3,692,676 or drag reducers such as those sold by Chemlink designated under the trademarks FLO 1003, FLO 1004, FLO 1005 and FLO 1008 have also been found to be effective. These polymeric species added as friction reducers or viscosity index improvers may also act as excellent fluid loss additives reducing or even minimize the use of conventional fluid loss additives. Latex resins or polymer emulsions may be incorporated as fluid loss additives. Shear recovery agents may also be used in embodiments.

[00149] Diverting agents may be added to improve penetration of the crosslinkable fluid into lower-permeability areas when treating a zone with heterogeneous permeability. The use of diverting agents in formation treatment applications is known, such as given in Reservoir Stimulation, 3^rd edition, M. Economides and K. Nolte, eds., Section 19.3.

[00150] In embodiments, the components of the crosslinkable fluid may be selected so that the morphology of the crosslinked structure, which forms by crosslinking the crosslinkable fluid, may be tuned to provide the desired sealing function. Such morphologies of the crosslinked fluid system may include, for example, a gelled material such as an elastic gel, a rigid gel, etc.; a slurried material; an elastic solid; a rigid solid; a brittle solid; a foamed material, and the like. In embodiments, the components of the crosslinkable fluid may be selected such that a crosslinking reaction substantially occurs at a temperature above the bottom hole static temperature (BHST), such as at least 20°C above BHST, or at least 50°C above BHST.

[00151] The crosslinkable fluid for treating a subterranean formation of the present disclosure may be a fluid that has a viscosity of above about 50 centipoise at 100 sec^"1, such as a viscosity of above about 100 centipoise at 100 sec^"1 at the treating temperature, which may range from a surface temperature to a bottom-hole static (reservoir) temperature, such as from about -40°C to about 150°C, or from about 10°C to about 70°C, or from about 25°C to about 60°C, or from about 32°C to about 55°C. In embodiments, the crosslinked structure formed may be a gel that is substantially non-rigid after substantial crosslinking. In some embodiments, the crosslinked structure formed is a non-rigid gel that may substantially return to its starting condition after compression with a linear strain of at least about 10%, such as at least about 25%, or greater than about 50%. Non-rigidity can be determined by any techniques known to those of ordinary skill in the art. The storage modulus G' of substantially crosslinked fluid system of the present disclosure, as measured according to standard protocols given in U.S. Pat. No. 6,011,075, the disclosure of which is hereby incorporated by reference in its entirety, may be about 150 dynes/cm² to about 500,000 dynes/cm², such as from about 1,000 dynes/cm² to about 200,000 dynes/cm², or from about 10,000 dynes/cm² to about 150,000 dynes/cm².

[00152] After the crosslinkable fluid is prepared, and before complete conversion to the crosslinked structure, it can be injected or conveyed into a subterranean formation to

substantially seal at least a portion of the subterranean formation upon complete conversion to the crosslinked structure. For example, after the crosslinker is released from the MOF conversion to the crosslinked structure may occur by polymerization of one or more of the components of the crosslinkable fluid. In some embodiments, after the crosslinker is released from the MOF conversion to the crosslinked structure may occur by polymerization of one or more of the components of the crosslinkable fluid after exposure to electromagnetic radiation. In embodiments, at least some of the crosslinkable fluid permeates a portion of the subterranean formation, such as a water-bearing subterranean formation.

[00153] In the methods of the present disclosure, crosslinking may be accomplished by exposing the crosslinkable fluid to predetermined conditions (such pH, ionic, heat, and/or pressure) that favor the release of the crosslinker from the MOF. In embodiments, the crosslinker may be substantially released from the MOF upon exposure to the predetermined conditions, such as about 75% of the crosslinker is released from the MOF, or about 95% of the crosslinker is released from the MOF, or about 99.9% of the crosslinker is released from the MOF, in a time no less than about 0.5 hours, or in a time no less than about one day, such as a time no less than about two weeks.

[00154] In embodiments, the crosslinkable components are not substantially crosslinked under the subterranean conditions (downhole conditions) until the crosslinkable fluid is introduced into the desired location. In other words, the diffusion (and/or release) of the crosslinker from the MOF (and thus crosslinking reaction between the crosslinker and the crosslinkable component) does not substantially occur before the crosslinkable fluid is downhole. For example, at least 80% (by weight) of the crosslinkable component remains uncrosslinked (under the conditions experienced downhole) until the crosslinkable fluid is positioned in the desired location in the wellbore in the vicinity of the subterranean formation to be treated and/or sealed, such as at least 95% (by weight), or as at least 99% (by weight) of the crosslinkable component remains uncrosslinked (under the conditions experienced downhole) before the crosslinkable fluid is positioned in the desired location in the wellbore in the vicinity of the subterranean formation to be treated and/or sealed. In embodiments, less than 5% (by weight) of the crosslinker diffuses (and/or is released) from the MOF before the crosslinkable fluid is positioned in the desired location in the wellbore in the vicinity of the subterranean formation to be sealed, such as less than 2% (by weight), or less than 0.5% (by weight) of the crosslinker diffuses from the MOF until the crosslinkable fluid is positioned in the desired location in the wellbore in the vicinity of the subterranean formation to be treated and/or sealed. [00155] In embodiments, the crosslinkable fluid systems are introduced into the subterranean material surrounding a wellbore by flowing the crosslinkable fluid system into the wellbore. In embodiments, the one or more crosslinkable components of the crosslinkable fluid does not crosslink until after its introduction into the wellbore, such as injection and/or permeation into the subterranean formation.

[00156] In embodiments, the crosslinked composition that is formed following the crosslinking reaction at least partially seals, and may completely seal, at least a portion of a subterranean formation through which crosslinkable fluid systems are dispersed. For example, crosslinking the crosslinkable fluid of the present disclosure may be conducted such that the permeability of the subterranean formation substantially decreases. In embodiments, after crosslinking the crosslinkable fluid of the present disclosure, the permeability of the subterranean formation, such as a water bearing subterranean formation, may decrease by at least about 80%, such as at least about 90%, or by at least about 99%.

[00157] Methods of the present disclosure may be used to seal or reduce the flow of an unacceptable amount of water (or other undesired material) into or near the wellbore. The phrase unacceptable amount of water (or other undesired material) may be determined on a case-by-case basis. As used herein, the terms "seal", "sealed" and "sealing" mean at least the ability to substantially prevent fluids, such as fluids comprising an unacceptable amount of water, to flow through the area where the crosslinkable components of the crosslinkable fluid were crosslinked. The terms "seal", "sealed" and "sealing" may also mean the ability to substantially prevent fluids from flowing between the medium where the crosslinkable components of the crosslinkable fluid were crosslinked and whatever surface it is sealing against, for example an open hole, a sand face, a casing pipe, and the like.

[00158] After at least a portion of the crosslinkable fluid has permeated the subterranean formation, such as water-bearing subterranean formation, the methods of the present disclosure may comprise crosslinking the crosslinkable components of the crosslinkable fluid to form a three-dimensional crosslinked structure and seal the subterranean formation. As discussed above, a subterranean formation is sealed if a portion or a majority of subterranean formation has been treated with the crosslinkable fluid and the crosslinkable components of the crosslinkable fluid in this treated zone have been crosslinked in a sufficient amount such that the permeability of the subterranean formation is reduced. For example, upon formation of a three-dimensional crosslinked structure as a result of crosslinking the crosslinkable components of the crosslinkable fluid of the present disclosure, the permeability of the subterranean formation may decrease by at least about 80%, such as by at least about 90%, or by at least about 99%. In embodiments, for a predetermined vertical region (depending on the vertical depth of the region to be sealed), the sealed zone may be a volume extending at least about 15 cm from the outer wall of the wellbore, such as a volume extending at least about 30 cm from the outer wall of the wellbore, or a volume extending at least about 50 cm from the outer wall of the wellbore.

[00159] The crosslinkable fluids of the present disclosure may be suitable for use in numerous subterranean formation types. For example, formations for which sealing with the crosslinkable fluids of the present disclosure may be used include sand, sandstone, shale, chalk, limestone, and any other hydrocarbon bearing formation.

[00160] The portion of the wellbore through which the crosslinkable fluid is injected into the treated zone can be open-hole (or comprise no casing) or can have previously received a casing. If cased, the casing is desirably perforated prior to injection of the crosslinkable fluid. Optionally, the wellbore can have previously received a screen. If it has received a screen, the wellbore can also have previously received a gravel pack, with the placing of the gravel pack optionally occurring above the formation fracture pressure (a frac-pack). Techniques for injection of fluids with viscosities similar to those of the crosslinkable fluids of the present disclosure are well known in the art and may be employed with the methods of the present disclosure. For example, known techniques may be used in the methods of the present disclosure to convey the crosslinkable fluids of the present disclosure into the subterranean formation to be treated.

[00161] In embodiments, the crosslinkable fluid may be driven into a wellbore by a pumping system that pumps one or more crosslinkable fluids into the wellbore. The pumping systems may include mixing or combining devices, wherein various components, such as fluids, solids, and/or gases maybe mixed or combined prior to being pumped into the wellbore. The mixing or combining device may be controlled in a number of ways, including, but not limited to, using data obtained either downhole from the wellbore, surface data, or some combination thereof. Methods of this disclosure may include using a surface data acquisition and/or analysis system, such as described in U.S. Pat. No. 6,498,988, the disclosure of which is hereby incorporated by reference in its entirety.

[00162] In embodiments, the crosslinkable fluid may be injected into the subterranean formation at a pressure either above or below the fracturing pressure of the formation. For example, the crosslinkable fluids will be injected below the formation fracturing pressure of the respective formation.

[00163] The volume of crosslinkable fluids to be injected into subterranean formation is a function of the subterranean formation volume to be treated and the ability of the crosslinkable fluid of the present disclosure to penetrate the subterranean formation. The volume of crosslinkable fluid to be injected can be readily determined by one of ordinary skill in the art. As a guideline, the formation volume to be treated relates to the height of the desired treated zone and the desired depth of penetration. In embodiments, the depth of penetration of the

crosslinkable fluid may be at least about up to 1000 feet from the outer wall of the wellbore into the subterranean formation, such as the depth of penetration of at least about 30 cm from the outer wall of the wellbore.

[00164] The ability of the crosslinkable fluid to penetrate the subterranean formation depends on the permeability of the subterranean formation and the viscosity of the crosslinkable fluid. In embodiments, the viscosity of the crosslinkable fluid is sufficiently low as to not slow penetration of the consolidating fluid into the subterranean formation. Techniques for fracturing an unconsolidated formation that include injection of consolidating fluids are known in the art. See U.S. Patent No. 6,732,800, the disclosure of which is herein incorporated by reference. A consolidating fluid may be injected through the wellbore into the formation at a pressure less than the fracturing pressure of the formation. The volume of consolidating fluid to be injected into the formation is a function of the formation pore volume to be treated and the ability of the consolidating fluid to penetrate the formation and can be readily determined by one of ordinary skill in the art.

[00165] In a low-permeability subterranean formation, the viscosity of the crosslinkable fluid is sufficiently low as to not slow penetration of the consolidating fluid into the subterranean formation. For example, in a low-permeability subterranean formation, suitable initial viscosities may be similar to that of water, such as from about from about 1 cP to about 1,000 cP, or be from about 1 cP to about 100 cP at the treating temperature, which may range from a surface temperature to a bottom-hole static (reservoir) temperature, such as from about -40 °C to about 150°C, or from about 10°C to about 70°C, or from about 25°C to about 60°C, or from about 32°C to about 55°C.

[00166] In embodiments, after the crosslinkable fluid penetrates the subterranean formation, the crosslinking reaction occurs, whereby the one or more the components of the crosslinkable fluid, including the crosslinker that is diffused from the MOF, are crosslinked. The crosslinked structure formed may comprise three-dimensional linkages that effectively blocks permeation of fluids through the sealed region. Thus, the sealed subterranean formation becomes relatively impermeable and any remaining pores in the sealed subterranean formation do not communicate with the wellbore and do not produce water.

[00167] The fluids and/or methods may be used for hydraulically fracturing a subterranean formation. Techniques for hydraulically fracturing a subterranean formation are known to persons of ordinary skill in the art, and involve pumping a fracturing fluid into the borehole and out into the surrounding formation. The fluid pressure is above the minimum in situ rock stress, thus creating or extending fractures in the formation. See Stimulation Engineering Handbook, John W. Ely, Pennwell Publishing Co., Tulsa, Okla. (1994), U.S. Patent No. 5,551,516 (Normal et al), "Oilfield Applications," Encyclopedia of Polymer Science and Engineering, vol. 10, pp. 328-366 (John Wiley & Sons, Inc. New York, New York, 1987) and references cited therein.

[00168] In various embodiments, hydraulic fracturing involves pumping a proppant-free viscous fluid, or pad - such as water with some fluid additives to generate high viscosity - into a well faster than the fluid can escape into the formation so that the pressure rises and the rock breaks, creating artificial fractures and/or enlarging existing fractures. Then, proppant particles are added to the fluid to form slurry that is pumped into the fracture to prevent it from closing when the pumping pressure is released. In the fracturing treatment, fluids of are used in the pad treatment, the proppant stage, or both.

[00169] MOFS AS A BREAKER CARRIER

[00170] In some embodiments, the target chemical entity that is reversibly loaded into the porous MOF of the treatment fluid is a breaker (and/or has a breaking function). The extent to which this target chemical entity may be loaded into the MOF is discussed above. The purpose of this component is to "break" or diminish the viscosity of a fluid, such as a viscosified treatment fluid, so that this fluid is more easily recovered from the formation during cleanup. Conventional fracturing fluid breaking technologies are known. For example, the design of fracturing treatments is described in U.S. Pat. No. 7,337,839, the disclosure of which is hereby incorporated by reference in its entirety.

[00171] "Breaker" and/or the phrase "breaking agent" (hereinafter collectively referred to as a breaker or breakers) refer, for example, to a compound or mixture that assists in diminishing the viscosity and/or the decomposition of a component of a viscosified fluid, such as the decomposition of a three-dimensional polymerized structure of the crosslinked composition discussed above, under at least some downhole conditions.

[00172] With regard to breaking down the viscosity, chemical reagents including, for example, oxidizers, chelants, or acids may be loaded into the MOFs and used in the methods of the present disclosure to diminish the viscosity of a fluid, such as a viscosified treatment fluid. After the breakers diffuse out of the MOF and/or or released from the MOFs, breakers may reduce the viscosity of a viscosified fluid comprising polymers, by reducing a polymer's molecular weight by the action of chemical reagent, such as an acid, base, an oxidizer, a chelant, or some combination of these on the polymer itself.

[00173] For example, in the case of the borate-crosslinked gels (discussed above), breakers, such as an acid, may be used, which after released from the acid-loaded MOF would decrease the pH and therefore decrease the effective concentration of the active crosslinker, the borate anion. Lowering the pH by emptying the acid-loaded MOF can easily remove the borate/polymer bonds because at lower pH, the borate associates with a hydrogen and is not available for crosslinking, thus gelation by borate ion is minimized.

[00174] In other embodiments, where the fracturing treatment involves the deployment of polylactic acid (PLA) materials, such as fibers or proppants, which is described in U.S. Patent Nos. 6,776,235; 7,451,812; 7,581,590; 8,066,068; 8,141,637; and 7,798,224, the disclosures of which are incorporated herein by reference in their entities, a base may function as a breaker because it may be used to raise the pH of the treatment fluid (post-deployment of the PLA fibers) after the base is released from the base-loaded MOF. The resulting increase in the pH may accelerate the PLA degradation, even under low temperature conditions, such as temperatures insufficient to thermally degrade PLA. Further details regarding loading a base into a MOF are discussed above.

[00175] In embodiments, a breaker-loaded MOF may be added to a viscosified or unviscosified treatment fluid before this fluid is introduced into the well bore, or the

breaker-loaded MOF may be added as a separate fluid, such as an aqueous or organic based fluid, that is introduced into the wellbore after at least a portion or the entire amount of viscosified or unviscosified treatment fluid has been introduced into the wellbore.

[00176] As used herein, the phrases "viscosified fluid," "viscosified treatment fluid" or

"viscosified fluid for treatment" (hereinafter generally referred to as a "viscosified fluid" unless specified otherwise) mean, for example, a composition comprising a solvent, a viscosifying material, such as a polymeric material, which may include any crosslinkable compound and/or substance with a crosslinkable moiety (hereinafter "crosslinkable component"), and optionally one or more breaker-loaded MOFs. The viscosified fluids of the present embodiments, may be substantially inert to any produced fluids (gases and liquids) and other fluids injected into the wellbore or around the wellbore.

[00177] In some embodiments, the methods of the present disclosure may comprise contacting and/or reacting a viscosified fluid, such as a viscosified polymer treatment fluid introduced into the formation via the wellbore, with a breaker that has diffused from a breaker- loaded MOF. In some embodiments, the methods of the present disclosure facilitate breaking of the viscosified fluid after a fracturing or well treatment has finished.

[00178] In embodiments, the "reaction" of the viscosified fluid ("viscosified treatment fluid" or "viscosified fluid for treatment") with the breakers to reduce the viscosity of the viscosified fluid (the breaking effect) occurs after the breaker has diffused and/or been released from the breaker-loaded MOF. In embodiments, after an effective amount of the breaker has been released from the breaker-loaded MOF, the reaction to reduce the viscosity of the viscosified treatment fluid may occur at any suitable temperature.

[00179] The effective amount of the breaker released from the breaker-loaded MOF into the viscosified or unviscosified treatment fluid (or aqueous or organic based fluid) may depend on several factors including the specific breaker selected, the amount and ratio of the other components in the viscosified or unviscosified treatment fluid (or aqueous or organic based fluid), the contacting time desired, the temperature, pH, and ionic strength of the viscosified or unviscosified treatment fluid (or aqueous or organic based fluid).

[00180] In embodiments where the breaker- loaded MOF is introduced in a fluid separate from the viscosified or unviscosified fluid, an effective amount of breaker may be reached when the amount of breaker diffused and/or released from the MOF into an aqueous or organic based fluid is in excess of about 0.001% by weight of the aqueous or organic based fluid, such as in an amount in the range of from about 0.002% to about 0.1% by weight of aqueous or organic based fluid, or in an amount in the range of from about 0.003% to about 0.01% by weight of the aqueous or organic based fluid, or in an amount in the range of from about 0.004% to about 0.008%) by weight of the aqueous or organic based fluid.

[00181] As suggested above, any known breaker that can reversibly associate with the porous MOF may be loaded into the MOF. Suitable breakers that may be loaded into the porous MOF for use in the methods of the present disclosure may include chemical reagents, such as oxidizers, chelants, and acids. Additional suitable breakers that may be loaded into the porous MOF for use in the methods of the present disclosure may also include the breakers described in U.S. Patent Application No. 13/595,644, which are breakers comprising at least one organic peroxide having a structural feature selected from cyclic peroxide segment and/or multiple linear peroxide moieties per molecule. The disclosure of U.S. Patent Application No. 13/595,644 is hereby incorporated by reference in its entirety. Additional suitable breakers that may be loaded into the porous MOF for use in the methods of the present disclosure may also include the breakers described in U.S. Patent Nos. 7,678,745; 7,888,297; 7,159,658; 6,924,254; 7,915,336; and 7,456,212; the disclosures of which are incorporated herein by reference in their entireties.

[00182] In embodiments, as discussed above with respect to the functional groups of the crosslinkers, the functional groups of the breakers and the porous MOF may be selected such that the functional groups of the porous MOF(s) non-covalently interact with the functional groups of the preselected breaker. Additionally, as discussed above with respect to crosslinkers, such porous MOF(s) of the present disclosure may also be selected such that when they are exposed to downhole conditions, the breakers are released, such as by diffusion and/or desorption processes, from the porous MOF(s). [00183] In embodiments in which the target chemical entity is a breaker, the pore size of the porous MOF may be controlled by the choice of the suitable ligand and/or of the at least one bidentate organic compound, such that the average pore size is in a range of from about 0.1 nm to about 75 nm, or an average pore size in a range of from about 0.5 nm to about 10 nm, or an average pore size in a range of from about 1.0 nm to about 5 nm.

[00184] In embodiments, the breaker may be loaded into a MOF where the pore volume of the unit cell of the MOF is uniform throughout the MOF, such that the distribution of pore volume across the entire MOF particle or composition is uniform and the pore size is

monodisperse. For example, the MOF into which the breaker is loaded may be a MOF that contains a single pore size, such as a single pore size that falls in a range of from about 0.1 nm to about 75 nm, or a single pore size that falls in a range of from about 0.5 nm to about 10 nm, or a single pore size that falls in a range of from about 1.0 nm to about 5 nm.

[00185] In some embodiments, the MOF into which the breaker is loaded may contain a distribution of pore sizes. In such embodiments, the MOFs into which the breaker is loaded may be MOFs in which more than 70% of the total MOF pore volume, such as more than 85%, or more than 99%, is formed by pores having a pore diameter less than 100 nm, such as less than 50 nm or less than 40 nm. In embodiments, no more than 5% of the total MOF pore volume, such as more than 2% of the total pore volume, or more than 0.5% of the total pore volume is formed by pores having a pore diameter greater than 50 nm, or greater than 100 nm or greater than 200 nm.

[00186] The porous MOFs suitable for use in the methods of the disclosure may comprise one or more of the following characteristics: a surface area (Langmuir surface area) of the plurality of pores is greater than about 500 m²/g; a surface area of the plurality of pores may be from about 500 to about 15,000 m²/g, or a surface area of the plurality of pores may be from about 1,000 to about 10,000 m²/g, or surface area of the plurality of pores may be from about 2,000 to about 6,000 m²/g; a surface area of the plurality of pores is about 800 to about 10,000 m²/g; an average pore volume of the plurality of pores comprising the porous MOF is in the range from about 0.005 to about 15 cm³/g, such as from about 0.05 to about 5 cm³/g; and the framework of the porous MOF has a density in a range of from about 0.03 to about 5 g/cm³, or from about 0.3 to about 1.5 g/cm³. [00187] In embodiments, the porous MOFs loaded with a breaker may comprise a thermal stability range (in which it will not decompose, or less than 2% by mass deterioration or decomposition, such as less than 1% by mass deterioration or decomposition) of at least 50°C higher than to the highest temperature that is observed in the subterranean formation being treated, such as a thermal stability range of at least up to 400°C, or a thermal stability range of greater than about 60°C to about 200°C, or a thermal stability range of greater than from about 80°C to about 190°C, or a thermal stability range of greater than from about 100°C to about 180°C. In embodiments, the porous MOFs loaded with a breaker may be selected to have chemical (and thermal) stability (in which it will not decompose, or less than 2% by mass deterioration or decomposition, such as less than 1% by mass deterioration or decomposition) that is sufficient to survive downhole chemical environments. In embodiments, the porous MOFs loaded with a breaker comprise a pressure stability range of at least 100 psi higher than the highest pressure that is observed in the subterranean formation being treated, such as a pressure stability range of greater than about 3,000 psi to about 25,000 psi, or a pressure stability range of greater than from about 4,000 psi to about 6,000 psi. In embodiments, the porous MOFs comprise a pH stability range of from about -1 to about 15, or a pH stability range of from about 5 to about 10, or a pH stability range of from about 6 to about 8.5.

[00188] The porous MOF(s) suitable for use in the methods of the present disclosure may be used for temporarily storing the breaker for a predetermined amount of time, for example, while the breaker is being transported downhole after incorporation into a treatment fluid. In embodiments, the breaker and MOF may be selected such that the breaker may be temporarily stored in the MOF for a predetermined time after loading (such as minutes, hours or days), for example, from about 5 to about 2,000 minutes, such as from about 10 to about 1,000 minutes, or 20 to about 500 minutes, or from about 30 to about 120 minutes. Subsequently, after the predetermined amount of time has passed, the breaker may be released from the porous MOF into the bulk of the crosslinked fluid, such as, for example, to initiate the depolymerization of the polymer contained therein and/or otherwise act in its intended capacity as a breaker.

[00189] In some embodiments, after the breaker loaded MOF has been exposed to a predetermined downhole condition (or set of conditions), such as a predetermined temperature, a predetermined pressure, a predetermined pH, a predetermined treatment fluid component concentration, or combination thereof, the breaker may be released from the porous MOF into the bulk of the crosslinked and/or viscous fluid, such as, for example, to initiate the depolymerization of the polymer contained therein and/or otherwise act in its intended capacity as a breaker.

[00190] In embodiments, the breaker is present in the loaded MOF at a weight percent of from about 25% to about 1,000% relative to the weight of the MOF alone (without any breaker present), or about 60%> or about 300%, or about 80 to about 200% relative to the weight of the MOF alone.

[00191] In the methods of the present disclosure, the uptake of the breaker into the porous MOF (to load the MOF with breaker) may occur by any suitable method, similar to those discussed above with respect to target chemical entities. For example, loading the porous MOF with the breaker may comprise soaking the MOF in a breaker slurry or solvent containing the breaker, such as an organic solvent (for example, a volatile organic solvent), for a predetermined amount of time, such as for about 4 hours or more, or for about 24 hours or more. Optionally, the breaker slurry or solvent containing the breaker may be refreshed and the soaking period may be repeated until the MOF is sufficiently loaded with breaker. In embodiments, the porous MOF may be optionally heated (with or without reduced pressure) at one or more temperatures before, during or after any of the above soaking periods to adjust (for example, increase or decrease) the amount of breaker loaded in the porous MOF. In embodiments, the heating temperature may be selected based on the thermal properties of the porous MOF and the identity of the soaking breaker slurry or solvent containing the breaker.

[00192] In some embodiments, the porous MOF may optionally be activated (as discussed above) prior to loading of any breaker therein in order to empty the plurality of pores and remove any residual chemical species that may remain after formation of the MOF.

[00193] In embodiments, the uptake of the breaker into the porous MOF, such as a porous

MOF tailored to selectively associate with the functional groups of the breaker, is reversible under predetermined conditions, such as downhole conditions. For example, the porous MOF may be selected such that under predetermined conditions the breaker moves from the surrounding bulk phase (for example, a liquid) into the porous MOF material (absorption) and/or moves from a bulk phase (for example, solid or liquid) onto a surface of the MOF (adsorption). The reverse of these processes transfers the breaker back into a bulk phase of the treatment fluid such that it may interact or react with the viscosified fluid being acted on.

[00194] In some embodiments, the "reaction" of the viscosified fluid (viscosified treatment fluid" or "viscosified fluid for treatment") with the breakers to reduce the viscosity of the viscosified fluid (the breaking effect) does not substantially occur, or does not occur, until the breaker is released from the breaker-loaded MOF, such as a breaker-loaded MOF that has been exposed to predetermined subterranean conditions. For example, such a reaction, which may include decomposing and/or depolymerizing the polymeric material of the viscosified fluid, does not substantially occur, or does not occur, until the breaker-loaded MOF is downhole and exposed to predetermined downhole conditions, such as a sufficient heat, a sufficient pressure, or a sufficient downhole component concentration, that is effective to initiate the release of the breaker from the breaker-loaded MOF. In specific embodiments, such a reaction, which may include the breaking agent reacting with the polymeric material of the viscosified fluid to decompose and/or depolymerize the polymeric material of the viscosified fluid, does not substantially occur, or does not occur, until the breaker-loaded MOF is downhole and the breaker is released from the loaded MOF and exposed to heat, such as a sufficient heat to initiate the reaction to reduce the viscosity of the viscosified treatment fluid, such as a temperature in the range of from about 79.4°C (175°F) to about 204°C (400°F), such as from about 79.4°C (175°F) to about 121°C (250°F), from about 93.3°C (200°F) to about 121°C (250°F), or from about 93.3°C (200°F) to about 107°C (225°F).

[00195] In embodiments, the breaker or breaking agent may comprise at least one organic peroxide. As described in U.S. Patent Application No. 13/595,644, which is incorporated by reference above, the phrase "breaking agent comprising at least one organic peroxide" refers, for example, to breakers or breaking agents comprising at least one organic peroxide molecule having a structural feature selected from cyclic peroxide segment and/or multiple linear peroxide moieties per molecule. In such embodiments, after an effective amount of the breaker has been released from the breaker-loaded MOF, the reaction to reduce the viscosity of the viscosified treatment fluid may be initiated by exposing the breaker to a temperature in the range of from about 80°C to about 204°C, such as from about 80°C to about 120°C, from about 90°C to about 120°C, or from about 90°C to about 100°C. [00196] In some embodiments, the breaker-loaded MOF may be present in the viscosified or unviscosified fluid before the viscosified or unviscosified treatment fluid is introduced into the wellbore. In such embodiments, the breaker-loaded MOF may be present in the viscosified or unviscosified fluid in any desired amount, such as in an amount that would to achieve a breaker weight percent in excess of about 0.001% by weight of the viscosified or unviscosified fluid upon release of the breaker from the breaker-loaded MOF, such as in an amount in the range of from about 0.01% to about 0.6%> by weight of the viscosified or unviscosified fluid upon release of the breaker from the breaker-loaded MOF, or in an amount in the range of from about 0.04% to about 0.3%) by weight of the viscosified or unviscosified fluid upon release of the breaker from the breaker-loaded MOF, or in an amount in the range of from about 0.05% to about 0.01% by weight of the viscosified or unviscosified fluid upon release of the breaker from the breaker- loaded MOF.

[00197] In embodiments, upon the release of the breaker from the breaker-loaded MOF, the concentration ratio of the breaker to the polymeric material (breakenpolymeric material) in the viscosified or unviscosified fluids may be in a range of from about 1 :100 to about 1 :50.

[00198] The release of the breakers during the methods of the present disclosure may be achieved by exposure to predetermined subterranean environmental conditions, such as a predetermined temperature, a predetermined pressure, a predetermined concentration or a predetermined pH, of the subterranean zone in which the breaker-loaded MOFs are placed.

[00199] In embodiments, the reduction of the viscosity, such as the viscosity reduction as a result of the breaking agent acting to decompose and/or depolymerize the polymeric material, of the viscosified fluid does not occur to any extent until the breaker-loaded MOF is exposed to sufficient downhole or subterranean conditions that would initiate the diffusion and/or release of the breaker from the breaker loaded MOF.

[00200] In embodiments, the breaking effect of the breaking agent may be accomplished either in the presence or absence of a breaker activator (also referred to as a "breaking aid"), which optionally may be loaded into a MOF. A breaker activator may be present to encourage the redox cycle that activates the breaking agent. In some embodiments, the breaker activator may comprise an amine, such as an oligoamine activators, for example, tetraethylenepentaamine (TEPA) and pentaethylenehexaamine (PEHA); or a metal chelated with chelating agents. Suitable metals may include iron, chromium, copper, manganese, cobalt, nickel, vanadium, aluminum, and boron. Further breaker aids may include ureas, ammonium chloride and the like, and those disclosed in, for example, U.S. Pat. Nos. 4,969,526, 4,250,044 and 7,678,745 the disclosures of which are incorporated herein by reference in their entireties.

[00201] The amount of breaker activator that may be included in the viscosified or unviscosified treatment fluid (or aqueous or organic based fluid) is an amount that will sufficiently activate the breaking effect of the breaker once the breaker diffuses and/or is released from the breaker-loaded MOF. In embodiments, the breaker activator will be present in the viscosified or unviscosified treatment fluid (or aqueous or organic based fluid) in an amount in the range of from about 0.01% to about 1.0% by weight, such as from about 0.05%> to about 0.5%) by weight, of the viscosified or unviscosified treatment fluid (or aqueous or organic based fluid).

[00202] The polymers present in the viscosified fluid or viscosified treatment fluid may be those commonly used with fracturing fluids, such as those mentioned above. The polymers may be used in either crosslinked or non-crosslinked form. The polymers may be capable of being crosslinked with any suitable crosslinking agent, such as metal ion crosslinking agents.

Examples of such materials include the polyvalent metal ions of boron, aluminum, antimony, zirconium, titanium, chromium, etc., that react with the polymers to form a composition with adequate and targeted viscosity properties for various operations.

[00203] In embodiments, the action of the breaker released from the breaker-loaded MOFs may decrease the viscosity of the viscosified fluid by at least an order of magnitude at the treating temperature, such as, for example, reducing the viscosity from at least about 10,000 centipoise at 100 sec^"1 at the treating temperature to no greater than about 1,000 centipoise at 100 sec^"1 at the treating temperature; or by at least two orders of magnitude at the treating

temperature, or to a viscosity below that of the initial unviscosified fluid (for example from at least about 10,000 centipoise at 100 sec^"1 at the treating temperature to less than about 100 centipoise at 100 sec^"1 at the treating temperature).

[00204] The unviscosified fluids or compositions suitable in the methods of the present disclosure may comprise a crosslinkable component, which are discussed in detail above. The concentration of the crosslinking agent (including the spread crosslinker) in the treatment fluid may be from about 0.001 wt % to about 10 wt %, such as about 0.005 wt % to about 2 wt %, or about 0.01 wt % to about 1 wt %.

[00205] Suitable solvents for use with the unviscosified fluid, viscosified fluid, and/or breaker-loaded MOFs may be aqueous or organic based, such as the aforementioned aqueous or organic solvents. In embodiments, the solvent, such as an aqueous solvent, may represent up to about 99.9 weight percent of the unviscosified or viscosified fluid, such as in the range of from about 85 to about 99.9 weight percent of the viscosified fluid, or from about 98 to about 99.7 weight percent of the viscosified fluid.

[00206] While the treatment fluids, such as viscosified fluids or viscosified treatment fluids of the present embodiments, are described herein as comprising the above-mentioned components, it should be understood that the treatment fluids may optionally comprise other chemically different materials, which optionally may be loaded in a MOF, some of which have already been described above. For example, the treatment fluids, such as unviscosified and/or viscosified fluids of the present embodiments, may further comprise stabilizing agents, surfactants, diverting agents, or other additives, which optionally may be loaded in one or more MOFs. Additionally, the treatment fluids, such as unviscosified and/or viscosified fluids, may comprise a mixture of various crosslinking agents, and/or other additives, such as fibers or fillers, provided that the other components chosen for the mixture are compatible with the intended application. In embodiments, the treatment fluids, such as unviscosified and/or viscosified fluids of the present embodiments, may further comprise one or more components selected from the group consisting of a conventional gel breaker (not loaded into a MOF), a buffer, a proppant, a clay stabilizer, a gel stabilizer, a surfactant and a bactericide. Furthermore, the treatment fluids, such as unviscosified and/or viscosified fluids of the present embodiments, may comprise buffers, pH control agents, and various other additives added to promote the stability or the functionality of the fluid. The components of the treatment fluids, such as unviscosified and/or viscosified fluids of the present embodiments, may be selected such that they may or may not react with the subterranean formation that is to be sealed.

[00207] MOFS AS AN ACIDIZING AGENT (OR ACID) CARRIER

[00208] In some embodiments, the target chemical entity that is reversibly loaded into the porous MOF (and/or composite MOF) of the treatment fluid is an acid or acidizing agent. Loading the acid in the porous MOF and/or composite MOF may allow for more efficient utilization and placement of the acid in the subterranean formation for the desired application or treatment. The ability of the MOF to temporarily store and/or chemically isolate the target chemical entity, such as an acid, until the target chemical entity, such as an acid, is in the vicinity of the target zones of interest minimizes the loss and inefficient reaction of the acid with components that are not of interest.

[00209] The acidizing treatments or methods of the present disclosure may be included in one or more of the treatment fluids comprising a MOF loaded with one or more acidizing agent and/or a composite MOF loaded with one or more acidizing agent, but otherwise use

conventional acidizing techniques known in the art.

[00210] Loading the acid or acidizing agent in the porous MOF or composite MOF may allow for more efficient utilization and placement of the acid or acidizing agent, which may be included, for example, in a stimulation fluid or treatment fluid. The ability of the MOF to temporarily store and/or chemically isolate the acid or acidizing agent until it is in the vicinity of the target zones of interest, such as a hydrocarbon zone, increases the radial penetration of the treatment fluid and minimizes the loss and inefficient treatment of formations or zones that are not of interest.

[00211] Acidizing is a known treatment used to stimulate hydrocarbon production from a well. Known acidizing treatments may be modified to incorporate the acid-loaded MOFs and/or acid-loaded composite MOFs as an acidizing agent source. For example, two types of acidizing treatments that may be modified to incorporate the acid-loaded MOFs and/or acid-loaded composite MOFs as an acidizing agent source may include: (1) matrix acidizing and (2) fracture acidizing. In embodiments, the acid-loaded MOFs and/or acid-loaded composite MOFs are sufficiently chemically and thermally stable during the conditions, such as the temperatures, injection rates and pressures, used during conventional fracture acidizing methods and also conventional matrix acidizing methods.

[00212] A variety of acidizing agents may be employed in the acid-loaded MOFs and/or acid-loaded composite MOFs. Examples of suitable acidizing agents include mineral acids, hydrochloric acid, hydrofluoric acid, sulfuric acid, nitric acid, perchloric acid, hydrobromic acid, phosphoric acid, boric acid, organic acids, acetic acid, ammonium bifluoride, formic acid, acetic acid, lactic acid, glycolic acid, maleic acid, tartaric acid, sulfamic acid, malic acid, citric acid, methyl-sulfamic acid, chloro-acetic acid, an amino-poly-carboxylic acid, 3-hydroxypropionic acid, a poly-amino-poly-carboxylic acid, a salt of any acid, and mixtures thereof.

[00213] In embodiments, the treatment fluids containing an acidizing agent may contain a sufficient amount of acid-loaded MOF and/or acid-loaded composite MOF in order to achieve an acid concentration in the range of from about 5% to about 80% by weight of the treatment fluid in the target area for treatment after the acid diffuses from the acid-loaded MOF, such as an acid concentration in the range of from about 10% to about 25% by weight of the treatment fiuid in the target area for treatment after the acid diffuses from the acid-loaded MOF, an acid concentration in the range of from about 12% to about 20% by weight of the treatment fiuid in the target area for treatment after the acid diffuses from the acid-loaded MOF.

[00214] In embodiments, the loaded MOF, such as a MOF loaded with a strong acid, like hydrochloric acid, may be distributed in a polymeric material, and/or coated in a polymeric material, to form an acid-loaded composite MOF. Any suitable polymeric material may be used to form the composite MOFs used in the methods of the present disclosure. However, where the acidizing agent is a strong acid, such as hydrochloric acid, the acid-loaded composite MOF may be prepared and subsequently distributed and/or coated in a polymeric material that is known to be stable to a strongly acidic environment. In embodiments, such an acid stable polymeric material may be a gel and/or inter-polymer complex (IPC) comprising polyacrylamide (greater than P/o) crosslinked by a non-metallic crosslinker as described above, and described in U.S. Patent Application Publication No. 2012/0138294, the disclosure of which has already been incorporated by reference.

[00215] In embodiments, loaded composite MOFs may be employed to further delay the diffusion of the target chemical entity (such as a strong acid) from the MOF to the bulk of the treatment fluid or acidizing fluid. Because the target chemical entity (such as a strong acid) will diffuse out of the MOF and then out of the acid stable polymeric material, the delay can be increased by increasing the size of the acid stable polymer particle into which the loaded MOF is dispersed and/or by increasing the depth of the layer of acid stable polymeric material coated on individual loaded MOFs. The effective amount of loaded MOF distributed in the acid stable polymeric material and/or the size of the acid stable polymer material particles may be varied as desired for the selected application.

[00216] In embodiments, the polymeric material of the composite MOF may be a gel that is known to be stable to exposure to strong acids, such as a polyacrylamide crosslinked with a non-metallic crosslinker wherein the polyacrylamide is present in the gel at a concentration of greater than or equal to about 1 wt%, or greater than or equal to about 2 wt% and less than or equal to about 10 wt%, based on the total weight of the gel, as described in U.S. Patent

Application Publication No. 2012/0138294.

[00217] In embodiments, the gel (produced according to U.S. Patent Application

Publication No. 2012/0138294) of the composite MOF loaded with a strong acid may absorb water when placed in contact with an aqueous solution. In embodiments, the gel of the composite MOF (loaded with a strong acid) in contact with water uptakes greater than or equal to about 100% by weight of water, or greater than or equal to about 200% by weight of water, based on the weight of the gel present.

[00218] In embodiments, the gel of the composite MOF may be formed at a pH of greater than or equal to about 9 and remains as a gel when the pH of the gel is lowered below 9, or when the pH of the gel is lowered below about 7, or when the pH of the gel is lowered below about 5, and/or when the pH of the gel is lowered below about 3. Accordingly, in embodiments, the gels of the acid loaded composite MOF may be non-reversible once formed, pH stable once formed, or a combination thereof. In embodiments, such a gel is coated on the MOF loaded with a strong acid, such as hydrochloric acid, after the pH stable gel is formed. In embodiments, the MOFs loaded with a strong acid, such as hydrochloric acid, are dispersed in such a gel after the pH stable gel is formed.

[00219] The water utilized to form the treatment fluid or acidizing fluid comprising the acid-loaded MOF and/or acid-loaded composite MOF can be any aqueous fluid which does not adversely react with the acidizing agent, or other components in the acidizing fluid. For example, the water can be fresh water, brine, salt containing water solutions such as sodium chloride solutions, potassium chloride solutions, ammonium chloride solutions, seawater, brackish water or the like. [00220] The treatment fluid or acidizing fluid comprising the acid-loaded MOF and/or acid-loaded composite MOF may also include one or more corrosion inhibitors and corrosion inhibitor intensifiers to prevent the aqueous acidizing agent solution from corroding metal pumps, tubular goods and the like. Such corrosion inhibitors, corrosion inhibitor intensifiers and other additives which can be included in the aqueous acidizing agent solution are known to those skilled in the art.

[00221] In embodiments, an acidizing treatment for a carbonate formation may include a sequential injection of at least two treatment fluids: an acidizing treatment fluid comprising an acid-loaded MOF and/or acid-loaded composite MOF, which optionally may be loaded with a mixture of acids, and an after flush treatment fluid. Optionally, a preflush treatment fluid may also be injected into the carbonate formation. In embodiments, an acidizing treatment for a sandstone formation may include a sequential injection of at least three treatment fluids: a preflush treatment fluid, an acidizing treatment fluid comprising an acid-loaded MOF and/or acid-loaded composite MOF, which optionally may be loaded with a mixture of acids, and an after flush treatment fluid.

[00222] In embodiments, the acid-loaded MOF and/or acid-load composite MOF may also be used as a scale dissolver to dissolve scale build-up. Once scale build-up is detected, suitable acid may be injected locally to remove the established deposits. This methodology also may be combined with the preventive application of inhibitors if desired (as discussed in more detail below). Examples of scale dissolvers comprise carbonate scale dissolvers, such as, for example, hydrochloric acid, acetic acid, formic acid, glutamic acid diacetic acid,

ethylenediaminetetraacetic acid, and hydroxyethylethylenediaminetriacetic acid; sulfate scale dissolvers, such as, for example, diethylenetriaminepentaacetic acid, and

diethylenetriaminepentaacetic acid (penta potassium salt); sulfide scale dissolvers, such as, for example, hydrochloric acid, and diammonium dihydrogen ethylenediammetetraacetate; and salt dissolvers, such as, for example, water.

[00223] The following are some of the known methods of acidizing hydrocarbon bearing formations which can be used as part of the present method: U.S. Pat. Nos. 3,215,199;

3,297,090; 3,307,630; 2,863,832; 2,910,436; 3,251,415; 3,441,085; and 3,451,818, which are hereby incorporated by reference in their entirety. These methods may be modified to incorporate an acid-loaded MOF and/or acid-loaded composite MOFs as the source of acidizing agent (or acid) in the acidizing procedures thereof, whether matrix acidizing or fracture acidizing.

[00224] In embodiments, as discussed above with respect to the functional groups of the target chemical entity, the functional groups of the acidizing agents and the MOFs may be selected such that the functional groups of the porous MOF(s) non-covalently interact with the functional groups of the acidizing agent. Additionally, as discussed above, the acid-loaded MOF and/or acid-loaded composite MOFs may also be selected such that when they are exposed to downhole conditions, the acidizing agents are released, such as by diffusion and/or desorption processes, from the acid-loaded MOF and/or acid-loaded composite MOFs.

[00225] In embodiments in which the target chemical entity is a breaker, the pore size of the porous MOF may be controlled by the choice of the suitable ligand and/or of the at least one bidentate organic compound, such that the average pore size is in a range of from about 0.1 nm to about 75 nm, or an average pore size in a range of from about 0.5 nm to about 10 nm, or an average pore size in a range of from about 1.0 nm to about 5 nm.

[00226] In embodiments, the acid and/or acidizing agent may be loaded into a MOF where the pore volume of the unit cell of the MOF is uniform throughout the MOF, such that the distribution of pore volume across the entire MOF particle or composition is uniform and the pore size is monodisperse. For example, the MOF into which the acid and/or acidizing agent is loaded may be a MOFs that contains a single pore size, such as a single pore size that falls in a range of from about 0.1 nm to about 75 nm, or a single pore size that falls in a range of from about 0.5 nm to about 10 nm, or a single pore size that falls in a range of from about 1.0 nm to about 5 nm.

[00227] In some embodiments, the MOF into which the acid and/or acidizing agent is loaded may contain a distribution of pore sizes. In such embodiments, the MOFs into which the acid and/or acidizing agent is loaded may be MOFs in which more than 70% of the total MOF pore volume, such as more than 85%, or more than 99%, is formed by pores having a pore diameter less than 100 nm, such as less than 50 nm or less than 40 nm. In embodiments, no more than 5% of the total MOF pore volume, such as more than 2% of the total pore volume, or more than 0.5% of the total pore volume is formed by pores having a pore diameter greater than 50 nm, or greater than 100 nm or greater than 200 nm.

[00228] The porous MOFs suitable for use in the methods of the disclosure may comprise one or more of the following characteristics: a surface area (Langmuir surface area) of the plurality of pores is greater than about 500 m²/g; a surface area of the plurality of pores may be from about 500 to about 15,000 m²/g, or a surface area of the plurality of pores may be from about 1,000 to about 10,000 m²/g, or surface area of the plurality of pores may be from about 2,000 to about 6,000 m²/g; a surface area of the plurality of pores is about 800 to about 10,000 m²/g; an average pore volume of the plurality of pores comprising the porous MOF is in the range from about 0.005 to about 15 cm³/g, such as from about 0.05 to about 5 cm³/g; and the framework of the porous MOF has a density in a range of from about 0.03 to about 1 g/cm³, or from about 0.3 to about 0.9 g/cm³.

[00229] In embodiments, the acid-loaded MOF and/or acid-loaded composite MOFs may comprise a thermal stability range (in which it will not decompose, or less than 2% by mass deterioration or decomposition, such as less than 1% by mass deterioration or decomposition) of at least 10°C higher than to the highest temperature that is observed in the subterranean formation being treated, such as a thermal stability range of at least up to 400°C, or a thermal stability range of greater than about 60°C to about 200°C, or a thermal stability range of greater than from about 80°C to about 190°C, or a thermal stability range of greater than from about 100°C to about 180°C. In embodiments, the acid-loaded MOF and/or acid-loaded composite MOFs may be selected to have chemical (and thermal) stability (in which it will not decompose, or less than 2% by mass deterioration or decomposition, such as less than 1% by mass deterioration or decomposition) that is sufficient to survive downhole chemical environments. In embodiments, the acid-loaded MOF and/or acid-loaded composite MOFs comprise a pressure stability range of at least 100 psi higher than the highest pressure that is observed in the subterranean formation being treated, such as a pressure stability range of greater than about 3,000 psi to about 25,000 psi, or a pressure stability range of greater than from about 4,000 psi to about 6,000 psi. In embodiments, acid-loaded MOF and/or acid-loaded composite MOFs comprise a pH stability range of from about -1 to about 7, or a pH stability range of from about 0.01 to about 6, or a pH stability range of from about 0.1 to about 5. In embodiments, the acid- loaded MOF and/or acid-loaded composite MOFs may stable at a pH in the range of from about -1 to about 6, such as a pH in the range of from 0.01 to about 4, or a pH in the range of from 0.1 to about 2.

[00230] The porous MOF(s) suitable for use in the methods of the present disclosure may be used for temporarily storing the acidizing agent for a predetermined amount of time, for example, while the acidizing agent is being transported downhole after incorporation into a treatment fluid. In embodiments, the acidizing agent and MOF may be selected such that the acidizing agent may be temporarily stored in the acid-loaded MOF and/or acid-loaded composite MOFs for a predetermined time after loading (such as minutes, hours or days), for example, from about 5 to about 2,000 minutes, such as from about 10 to about 1,000 minutes, or 20 to about 500 minutes, or from about 30 to about 120 minutes. Subsequently, after the predetermined amount of time has passed, the acidizing agent may be released from the acid-loaded MOF and/or acid- loaded composite MOFs into the bulk of the treatment fluid, such as, for example, to react with the target formation and/or otherwise act in its intended capacity as an acidizing agent.

[00231] In some embodiments, after the acid-loaded MOF and/or acid-loaded composite

MOFs has been exposed to a predetermined downhole condition (or set of conditions), such as a predetermined temperature, a predetermined pressure, a predetermined pH, a predetermined treatment fluid component concentration, or combination thereof, the acidizing agent may be released from the acid-loaded MOF and/or acid-loaded composite MOFs into the bulk of the treatment fluid, such as, for example, to react with the target formation and/or otherwise act in its intended capacity as an acidizing agent.

[00232] In embodiments, the acidizing agent is present in the acid-loaded MOF and/or acid-loaded composite MOFs at a weight percent of from about 25% to about 1,000% relative to the weight of the MOF alone (without any acidizing agent present), or about 60%> or about 300%, or about 80 to about 200% relative to the weight of the MOF alone (with respect to the composite MOFs, not including the weight polymeric material).

[00233] In the methods of the present disclosure, the uptake of the acidizing agent into the porous MOF (to load the MOF with acidizing agent) may occur by any suitable method, similar to those discussed above with respect to target chemical entities, with the exception that in some embodiments, the entire loading process may occur at a temperature below about 0°C, such as temperature below about -20°C, or a temperature in the range of from about -20°C to about -50 °C.

[00234] In embodiments, loading the porous MOF with the acidizing agent may comprise soaking the MOF in an acidizing agent slurry or solvent containing the acidizing agent, for a predetermined amount of time, such as for about 4 hours or more, or for about 24 hours or more, optionally at a temperature below about 0°C, such as temperature below about -20°C, or a temperature in the range of from about -20°C to about -50 °C. Optionally, the acidizing agent slurry or solvent containing the acidizing agent may be refreshed and the soaking period may be repeated until the MOF is sufficiently loaded with acidizing agent.

[00235] In embodiments, the uptake of the acidizing agent into the porous MOF, such as a porous MOF tailored to selectively associate with the functional groups of the acidizing agent, is reversible under predetermined conditions, such as downhole conditions. For example, the porous MOF may be selected such that under predetermined conditions the acidizing agent moves from the surrounding bulk phase (for example, a liquid) into the porous MOF material (absorption) and/or moves from a bulk phase (for example, solid or liquid) onto a surface of the MOF (adsorption). The reverse of these processes transfers the acidizing agent from the MOF directly back into a bulk phase of the treatment fluid (acid-loaded MOF), or to the polymeric material (acid-loaded composite MOFs) where additional delay may be achieved while the acidizing agent is diffusing through the polymeric material before making it back into a bulk phase of the treatment fluid, where the acidizing agent may interact or react with the target formation being acted on.

[00236] ADDITIONAL EMBODIMENTS

[00237] In embodiments, the pore volume of the MOF may be saturated with gaseous species, such as, for example, N₂, C0₂, C_nH_2n+2 (n<5 - methane (CH₄), ethane (C₂H₆), propane (CsHg) butane (C₄H₁₀)). The gas species may be introduced prior to or simultaneously with the treatment fluids described above, where the discharge of the absorbed gases is triggered by the pressure differential to which they are exposed upon introduction to the subterranean

formation. The discharged of the above gaseous species may increase the fracture length and/or width. Further, an MOF saturated with a gaseous species may also be used in wellbore gas lifting equipment. Additional details describing gas lifting equipment are described in U.S. Patent Application Pub. Nos. 2005/0155756, 2007/0227739, 2007/0235197, 2008/0121397, 2008/0257556 and U.S. Patent No. 5,377,764, the disclosures each of which are incorporated by reference herein in their entirety.

[00238] In one embodiment, at 298K and 435psi, one gram MOF can absorb up to 2.5 grams C0₂. Under reservoir conditions, such as, for example, 423K and 7250 psi, the full discharge (at for example the interface of wellbore / fracture where significant pressure differential is encountered) of this amount of C0₂ accounts for about 0.5 cubic meter in volume.

[00239] In embodiments, the MOF may be loaded with one or more cementing activator or accelerator. The cementing activator may function the activator activate and/or accelerate the set up or curing time for the cement and thus reduce the wait on cement (WOC) time. In the present application, accelerated set times may be less than 12 hours, less than 10 hours, less than 8 hours, less than 6 hours, less than 4 hours, and less than 2 hours. Examples of cementing activators include amines, such as triethanol amines and diethanol amines; metal salts, such as sodium, calcium, magnesium, zinc, and iron salts (calcium sulfate), metal halides, such as metal chlorides and metal bromides; metal formates, and combinations thereof. Additional details regarding cementing activator are described in U.S. Pat. Nos. 2,437,842; 3,553,077; 4,257,814, 4,741,782, and U.S. Pat. No. 6,869,474, each of which is incorporated by reference in its entirety. One or both of the elevated temperature (which facilitates higher mobility) and the chemical potential difference may be driven by the cementing process that consumes the cementing activator.

[00240] In additional embodiments, the MOF may loaded with a cement retarder.

Examples of cement retarders include lignosulfonates (filtered, purified or modified), such as, for example, glucoheptanates; alkali lignosulfonates, such as, calcium lignosulfonate and sodium lignosulfonates; organophosphates such as, mono-phosphates (ortho-phosphates P0₄, meta- phosphates P0₃) or acyclic poly-phosphates (pyrophosphates P₂0₇ ⁴, tripolyphosphates P3O10⁵), or cyclic poly-phosphates; synthetic retarders, such as maleic anhydride and 2-acrylamido-2- methylpropanesulfonic acid (AMPS) copolymers; inorganic compounds, such as borates and zinc oxide, or one of the salt materials described above. The above cement retarders may be used alone or in combination with any of the materials described herein. [00241] In embodiments, the MOF may also be loaded with hydrogen sulfide scavenger.

Hydrocarbons, such as crude oil, may contain acids in several forms. These acids may be mineral acids such as, hydrochloric and phosphoric acids. A common inorganic acid found in

hydrocarbons is hydrogen sulfide and various oxidized forms of hydrogen sulfide such as sulfuric acid. Hydrogen sulfide is both toxic and corrosive. Neither of these properties is usually desirable in hydrocarbons. Hydrogen sulfide may be present when crude oil is produced from an oil well. It may also be present or created by decomposition of other sulfur containing

compounds during a refining process. If not removed, generally by scavenging, it may still be present after refining in hydrocarbon products ranging from light lubricating oils to fuels to heavy fuels to bitumen. Examples of hydrogen sulfide scavengers include an oxidant, such as an inorganic peroxide (e.g., sodium peroxide, or chlorine dioxide), or sodium bromated, sodium nitrite or an aldehyde having from 1-10 carbons atoms such as, for example, formaldehyde, glutaraldehyde or (meth)acrolein. Additional examples of hydrogen sulfide scavenger compounds includes amines such as, for example, monoethanolamine (MEA), diethanoloamine (DEA), diisopropylamine, diglycolamine (DGA) and N-methyldiethanolamine (MDEA). The hydrogen sulfide scavenger may be released from the MOF individually, or through a

combination of (1) thermal energy that facilitates more rapid mobility and (2) the chemical potential, i.e., the chemical reaction consumes the outbound scavenger.

[00242] Crude oil typically contains one or more solids such as gas hydrates, asphaltenes, waxes such as paraffins, and scale, among others. Further, in oil production, generally at some point oil such as crude oil is transported in liquid form through long stretches of pipes. The deposition of these solids from the crude oil onto the interior surfaces of the pipes can have a drastic and negative impact on the oil flow through these pipes.

[00243] In embodiments, the MOF is loaded with a gas hydrate inhibitor. Gas hydrates are also referred to as "clathrates". As used herein, "clathrate" is a weak composite made of a host compound that forms a basic framework and a guest compound that is held in the host framework by inter-molecular interaction, such as hydrogen bonding, Van der Waals forces, and the like. Clathrates may also be called host-guest complexes, inclusion compounds, and adducts. As used herein, "clathrate hydrate" and "gas hydrate" are interchangeable terms used to indicate a clathrate having a basic framework made from water as the host compound. A hydrate is a crystalline solid which looks like ice, and forms when water molecules form a three-dimensional cage-like structure around a "hydrate-forming constituent."

[00244] A "hydrate-forming constituent" refers to a compound or molecule in petroleum fluids, including natural gas, which forms hydrate at elevated pressures and/or reduced temperatures. Illustrative hydrate-forming constituents include, but are not limited to, hydrocarbons such as methane, ethane, propane, butane, neopentane, ethylene, propylene, isobutylene, cyclopropane, cyclobutane, cyclopentane, cyclohexane, and benzene, among others. Hydrate-forming constituents can also include non-hydrocarbons, such as oxygen, nitrogen, hydrogen sulfide, carbon dioxide, sulfur dioxide, and chlorine, among others.

[00245] The gas hydrates resemble ice but remain solid at temperature and pressure conditions above the freezing point of water. They generally consist of about 80 to 85 mol % water and 15 to 20 mol % gas. The gas of most hydrates is predominantly methane, with smaller quantities of other light hydrocarbon gases, such as ethane, propane and butanes. These gas hydrates vary in composition depending upon the conditions. Two crystal structures of hydrates exist, referred to as Structure I and Structure II. See, Collett, T. S. and Kuuskraa, V. A.,

"Hydrates Contain Vast Stores of World Gas Resources," Oil and Gas Journal, May 11, 1998, pp. 90-95. In the hydrate lattice of Structure I, the hydrate unit cell consists of 46 water molecules that form two small dodecahedral voids and six large tetradecahedral voids that can only hold small gas molecules, such as methane and ethane. In Structure II, the hydrate structure consists of 16 small dodecahedral and 8 large hexakaidechedral voids formed by 136 water molecules. In Structure II, larger gases can be contained within the voids, such as propane and isobutane.

[00246] When hydrocarbon gas molecules dissolve in water, the hydrogen-bonded network of water molecules encapsulates the gas molecules to form a cage-like structure or hydrate. Higher pressures and lower temperatures foster the formation of these structures. These hydrates grow by encapsulating more and more gaseous molecules to form a crystalline mass. The crystalline mass agglomerates to form a larger mass that can result in a plugged transmission line. The hydrocarbon gases that form the majority of the hydrates include methane, ethane, propane, n-butane, iso-butane, n-pentane, iso-pentane, and combinations of these gases. [00247] Gas hydrate inhibitors may be classified in groups: thermodynamic hydrate inhibitors, kinetic hydrate inhibitors and anti-agglomerate hydrate inhibitors. Suitable examples thermodynamic hydrate inhibitors, include alcohols, such as methanol or glycols.

[00248] Kinetic hydrate inhibitors have been identified to prevent these hydrate formations so that the fluids can be pumped out before a catastrophic hydrate formation occurs. The kinetic inhibitors prevent, suppress or delay hydrate crystal nucleation and disrupt crystal growth. These kinetic hydrate inhibitors contain moieties similar to gas molecules previously mentioned. It is suspected that these kinetic inhibitors prevent hydrate crystal growth by becoming incorporated into the growing hydrate crystals, thereby disrupting further hydrate crystal growth. The growing hydrate crystals complete a cage by combining with the partial hydrate-like cages around the kinetic hydrate inhibitor moieties containing gas-like groups. These inhibitors are effective with or without the presence of a liquid hydrocarbon phase, but they are typically less effective in preventing the hydrate formation as the production pressure increases. Examples of kinetic hydrate inhibitors include poly(N-methylacrylamide), poly(N,N- dimethylacrylamide), polyisopropylacrylamide, poly(N-ethylacrylamide), polyacryloyl pyrrolidine, poly(N,N-diethylacrylamide), poly(N-methyl-N-vinylacetamide), poly(2- ethyloxazoline), polyvinylcaprolactum (PVCap), poly(N-vinylpyrrolidone), and poly(N- vinylcaprolactam) .

[00249] Unlike the kinetic hydrate inhibitors, anti-agglomerate hydrate inhibitors are effective only in the presence of an oil phase. These inhibitors do not inhibit the formation of gas hydrates to the same level as kinetic inhibitors, rather their primary activity is in preventing the agglomeration of hydrate crystals. The oil phase provides a transport medium for the hydrates which are referred to as hydrate slurries so that the overall viscosity of the medium is kept low and can be transported along the pipeline. As such, the hydrate crystals formed in the water- droplets are prevented from agglomerating into a larger crystalline mass. Examples of several chemicals acting as anti-agglomerate hydrate inhibitors have been reported in U.S. Pat. Nos. 5,460,728; 5,648,575; 5,879,561; and 6,596,911, each of which is incorporated by reference herein in its entirety. The hydrate inhibitor may be released from the MOF individually, or through a combination of (1) thermal energy that facilitates more rapid mobility and (2) the chemical potential, i.e., the chemical reaction consumes the outbound hydrate inhibitor. [00250] In embodiments, the MOF may be loaded with an asphaltene inhibitor or a wax inhibitor. Asphaltene fractions are conventionally defined as the portion of crude oil or bitumen which precipitates on addition of a low molecular weight paraffin, typically n-pentane or n- heptane, but which is soluble in toluene. Asphaltenes are amorphous solids having a complex structure formed of condensed aromatic nuclei associated with alicyclic groups and involve carbon, hydrogen, nitrogen, oxygen and sulfur. The asphaltene particles are typically surrounded by naturally occurring resins which are thought to provide some dispersion stability.

[00251] Asphaltenes are typically present in crude oils and are largely stable in their native formation. Crude oil is conventionally described as a colloidal system which is stabilized to some extent by the naturally occurring resins which act as peptizing agents. Changes in pressure, temperature and phase composition however may result in destabilization and deposition, such as precipitation, of the asphaltenes in the formation. Such deposition may have catastrophic effects on the recovery of the crude from the formation. Destabilization and deposition of the aggregated asphaltene particles on the surface of, or in the pores in, the reservoir results in a loss of permeability and often significant reduction in production therefrom. Once blocked, efforts to remove the deposited asphaltene, using solvents such as toluene and the like, may be only minimally successful, are costly and present environmental hazards.

Asphaltenes often precipitate, along with other solids such as paraffin waxes, when crude oil is transported via pipe, such as from a geologic structure to a wellhead via a production pipeline or from a wellhead or a storage vessel to a refinery via a pipeline. Asphaltene deposits can plug downhole tubulars, well-bores, choke off pipes and interfere with the functioning of separator equipment. Precipitated asphaltenes are not desirable, as they can foul and lead to fouling of process equipment

[00252] Examples of asphaltene inhibitors include sulphonic acids; alkyl aryl sulphonic acids; aryl sulfonates; lignosulfonates; alkylphenol/aldehyde resins and similar sulfonated resins; polyolefin esters; polyolefin imides; polyolefin esters with alkyl, alkylenephenyl or

alkylenepyridyl functional groups; polyolefin amides; polyolefin amides with alkyl,

alkylenephenyl or alkylenepyridyl functional groups; polyolefin imides with alkyl,

alkylenephenyl or alkylenepyridyl functional groups; alkenyl/vinyl pyrrolidone copolymers; graft polymers of polyolefins with maleic anhydride or vinyl imidazole; hyperbranched polyester amides; polyalkoxylated asphaltenes and combinations thereof. Additional details regarding asphaltene inhibitors are described in U.S. Patent Application Pub. No. 2011/02203353, the disclosure of which is incorporated by reference herein in its entirety. The discharge of the asphaltene inhibitor from the MOF may be accomplished individually, or through a combination of (1) thermal energy that facilitates more rapid mobility and (2) the chemical potential, i.e., the chemical reaction consumes the outbound asphaltene inhibitor.

[00253] In embodiments, the MOF may be loaded with a wax inhibitor. Paraffin wax accounts for a significant portion of a majority of crude oils that are greater than 20°C. Paraffin has a straight chain linear structure comprised entirely of carbon and hydrogen. The paraffins with molecules that are larger than C20H42 are the components that cause deposition or congealing oil in crude oil systems. Paraffin can deposit from formation pores to the pipeline that deliver oil to the refineries. The deposits vary in consistency from rock hard for the highest chain-length paraffin to very soft, mayonnaise-like congealing oil deposits. Paraffin (wax) is mostly found as a white, odorless, tasteless, waxy solid, with a typical melting point ranges from 47°C. to 64°C. and a density of around 0.9 g/cm³. Further, paraffin may be insoluble in water, but can be soluble in various types of organic solvents, such as, for example, ether, benzene, and certain esters. Examples of wax or paraffin inhibitors include polyacrylate, polymethacrylate, polyethylene vinyl acetate, poly α-olefm maleic anhydrite and combinations thereof.

[00254] The discharge of the wax inhibitor from the MOF may be accomplished individually, or through a combination of (1) thermal energy that facilitates more rapid mobility and (2) the chemical potential, i.e., the chemical reaction consumes the outbound wax inhibitor.

[00255] In embodiments, the MOF may be loaded with a scale inhibitor. Examples of suitable scale inhibitors comprise carbonate scale inhibitors, such as, for example, pteroyl-L- glutamic acid, alkyl ethoxylated phosphates, ethylene diamine tetramethyl phosphonic acid, hexamethylenediaminepenta (methylenephosphonic) acid, diethylenetriaminepenta

(methylenephosphonic) acid, N-bis(phosphonomethyl) amino acid, N-substituted aminoalkane- 1,1-diphosphonic acids, ether diphosphonate, and phosphinicosuccinic acid oligomer; sulfate scale inhibitors, e.g. polyepoxysuccinic acid, polyaspartic acid, polyamino acid, homopolymers and copolymers of acrylic acid, polyvinyl sulfonate, mixtures of aminotri (methylenephosphonic acid and diethylenetriamine penta(methylenephosphonic acid, and polyposphate; sulfide scale inhibitors, e.g. hydroxyethylacrylate/acrylic acid copolymer (ZnS); or salt inhibitors, e.g. nitrilotriacetamide and its salts, potassium ferrocyanide, and urea and ammonium chloride mixture, such as phosphonated carboxylic acids or polymers. The scale inhibitors may be released from the MOF in a water producing zone of the subterranean formation by the outward diffusion of the scale inhibitor upon exposure to the increased temperature of the formation. The minimum level of temperature required to release the scale inhibitor from the MOF may be from about 150°F to about 225°F.

[00256] In embodiments, the MOF may be loaded with one or more of the surfactants described above. Furthermore, the MOF may also be load with a wettability enhancer (also referred to as a wettability agent), which is a type of nonionic surfactant. Additional examples of nonionic surfactant, in addition to those discussed above, include methyl gluceth-10, PEG-20 methyl glucose distearate, PEG-20 methyl glucose sesquistearate, Cn_i5 pareth-20, ceteth-8, ceteth-12, dodoxynol-12, laureth-15, PEG-20 castor oil, polysorbate 20, steareth-20,

polyoxy ethylene- 10 cetyl ether, polyoxy ethylene- 10 stearyl ether, polyoxy ethylene -20 cetyl ether, polyoxyethylene-10 oleyl ether, polyoxyethylene-20 oleyl ether, an ethoxylated nonylphenol, ethoxylated octylphenol, ethoxylated dodecylphenol, or ethoxylated fatty (C6-C22) alcohol, including 3 to 20 ethylene oxide moieties, polyoxyethylene-20 isohexadecyl ether, polyoxy ethylene-23 glycerol laurate, polyoxy-ethylene-20 glyceryl stearate, PPG- 10 methyl glucose ether, PPG-20 methyl glucose ether, polyoxyethylene-20 sorbitan monoesters, polyoxyethylene-80 castor oil, polyoxyethylene-15 tridecyl ether, polyoxy-ethylene-6 tridecyl ether, laureth-2, laureth-3, laureth-4, PEG-3 castor oil, PEG 600 dioleate, PEG 400 dioleate, and mixtures thereof.

[00257] The discharge of the surfactant from the MOF may be accomplished individually, or through a combination of (1) thermal energy that facilitates more rapid mobility and (2) the chemical potential, i.e., the chemical reaction consumes the outbound wax inhibitor. The process may be modulated by blending the surfactant with a suitable linear gel before being absorbed into the MOF cavities.

[00258] In embodiments, the MOF may be loaded with a tracer material, such as, for example a chemical species for a cement bond log, such, as, for example boron species. The concentration levels of the chemical species in the may be used as a real time indicator of the cement bonding process. Alternatively, the MOF may be used to encapsulate materials within the cement slurry and such encapsulation would be to generate heat, which could then be detected.

[00259] The foregoing is further illustrated by reference to the following examples, which are presented for purposes of illustration and are not intended to limit the scope of the present disclosure.

[00260] EXAMPLES

[00261] Five MOF materials were selected for testing: (1) MOF-1, made from aluminium fumarate, CAS number 132041-53-3, which was a MOF prepared from 2-butenedioic acid (2E) and an aluminium salt, possessed a specific surface area of 975 m²/g and an average pore size of about 0.6 nm, and (2) MOF-2, which was a MOF prepared from lH-imidazole, 2-methyl, zinc salt possessed a specific surface area of 1,336 m²/g and an average pore size of about 0.6 nm. (3) MOF-3: Aluminum terephthalate, MIL-53(A1), obtained from Sigma- Aldrich. (4) MOF-4:

Copper benzene-l,3,5-tricarboxylate, Cu-BTC MOF, HKUST-1, obtained from Sigma-Aldrich. (5) MOF-5: Fe-BTC, Iron 1,3,5-benzenetricarboxylate, Empirical Formula (Hill Notation):

C₉H₃Fe0₆, CAS Number: 1195763-37-1, obtained from Sigma-Aldrich.

[00262] The particle size distribution of the first two MOF samples (MOF-1 and MOF-2) was measured using a Malvern Mastersizer 2000 by dispersing the powders into an aqueous medium. The results of this test are shown in FIG. 1 and below in Table 1. As shown in FIG. 1, MOF-1 shows two sub-domains of particle sizes, and MOF-2 shows three sub-domains of particle sizes.

Table 1 : Particles size distribution analysis

[00263] MOF-1 crosslinker loading: 2 grams of a powder of MOF-1 were placed in a glass container equipped with a magnetic stirrer bar, and the container was placed on top of a stirring plate. Next, 7 milliliters (mL) of a crosslinker slurry were added drop wise, while stirring. At the end of the mixing process, the mixture was held under vacuum at a pressure of 100 mbar for several hours until there was no visible excess water. The dried mixture was weighed again and the loading level of the crosslinker in the MOF was estimated to be 1.44 grams or 72% (1.44/2.0).

[00264] MOF-2 crosslinker loading: 2 grams of a powder of MOF-2 were placed in a glass container equipped with a magnetic stirrer bar, and the container was placed on top of a stirring plate. Next, 7 mL of a crosslinker slurry were added drop wise, while stirring. At the end of the mixing process, the mixture was held under vacuum at a pressure of 100 mbar for several hours until there was no visible excess water. The dried mixture was weighed again and the loading level of the crosslinker in the MOF was estimated to be 3.7 grams or 185% (3.7/2.0).

[00265] MOF-1 Crosslinking Onset: A linear gel of guar was prepared by hydrating 0.9 grams of guar in 250 mL tap water for a period of approximately 20 minutes in a blender. This resulted in a concentration of 30 pounds of guar per thousand (gpt) gallons (U.S. gallons) of water. Next, the solution pH was raised to 12 by adding a diluted sodium hydroxide (drop wise). For the control sample, this was followed by adding the crosslinker (0.2 mL alone, not loaded into a MOF) at the level of 1.6 gallon per thousand gallons (U.S. gallons). For the crosslinker loaded MOF-1, various levels (0.05 grams, 0.1 grams, and 0.2 grams) of active content were loaded into MOF-1 based on the above estimation. Samples were placed in a Bohlin Gemini 150 rheometer while the time to reach a fully crosslinked gel with stable viscosity was monitored. The results of this test are shown in FIG. 2.

[00266] The results indicate that a clear delay in the onset of the crosslinking event for the crosslinker loaded MOF-1 materials. The data demonstrate that the extent of the delay is inversely proportional to the concentration of the MOF-l/crosslinker system in the crosslinkable component, therefore can be modulated as desired.

[00267] MOF-2 Crosslinking Onset: A linear gel of guar was prepared by hydrating 0.9 grams of guar in 250 mL of tap water for a period of approximately 20 minutes in a blender. This resulted in a concentration of 30 pounds of guar per thousand gallons (U.S. gallons) of water. Next, the solution pH was raised to 12 by adding a diluted sodium hydroxide (drop wise). For the control sample, this was followed by adding the crosslinker (0.6 mL) at the level of 1.6 gallon per thousand gallons (U.S. gallons). For the crosslinker loaded MOF-2, various concentration levels (0.5 grams and 0.7 grams) of crosslinker were loaded into the MOF-2 based on the above estimation. Samples were placed in a device shown in FIG. 3 while the time to reach a fully crosslinked gel with stable viscosity was monitored. The results of this test are shown in FIG. 4.

[00268] The results indicate that the crosslinker loaded MOF-2 system clearly delays the onset of the crosslinking event. Similar to the crosslinker loaded MOF-1 system, the extent of the delay is inversely proportional to the concentration of the crosslinker loaded MOF-2 system. Thus, the delaying effect may be modulated according to the procedures developed for a given wellsite.

[00269] MOF-1 Thermo gravimetric Analysis: The thermogravimetric characteristics of crosslinker loaded MOF-1 (10 mg sample) were probed using a TA Instruments TGA 4500. The results of this test are shown in FIG. 5. At a heating rate of 10 °C/minute, it was revealed that the MOF-1 binding of crosslinker- 1 was thermally stable relative to conditions that may be experienced downhole. In comparison to the MOF sample baseline, FIG. 5 shows that at up to 96°C level there was less than 1% of the absorbed species being discharged from the MOF. Further heating up to 190°C, there was an additional discharge of about 6% total weight, indicating an unidentified mutual stabilization effect between MOF and the crosslinker species absorbed into its pore volumes. Up to this point, the sample was under the coverage of a nitrogen blanket, which was subsequently switched to air at 200°C where the sample was burnt.

[00270] MOF-1 Differential Scanning Calorimetric Analysis: The differential scanning calorimetric characteristics of crosslinker loaded MOF-1 was probed using a TA Instruments DSC 42000. The results of this test are shown in FIG. 6. For a 10 mg sample, at a heating rate of 10°C/min, the crosslinker loaded MOF-1 shows three distinctive endothermic processes up to 120°C, the first of which (up to 80°C or so) being closely associated to the MOF substrate itself as demonstrated by its resemblance to the MOF baseline. The subsequent second and third endothermic processes are more rapid, as evident by the steeper slopes of heat flow rate. Further heating up to 190°C displays a continuous exothermic process, which almost fully recovered the thermal exchange in the previous endothermic processes. Reverse of temperature scan direction results in a featureless straight line, excluding any possibility of subtle phase changes in the preceding events.

[00271] MOF-2 Differential Scanning Calorimetric Analysis: The differential scanning calorimetric characteristics of crosslinker loaded MOF-2 was probed using a TA Instruments DSC 42000. The results of this test are shown in FIG. 7. For a 10 mg sample, in the temperature range between ambient temperature and 200°C, three discrete stages of mass loss were observed, accounting for 9.25%, 2.82% and 5.55% mass loss, respectively. In comparison, the MOF sample itself shows no observable mass loss in the same temperature range. This may demonstrate that the multiple stage endothermic process originated from the outward diffusion of the crosslinker species absorbed at different depth in the porous MOF.

[00272] Further differential scanning calorimetric tests were run against a featureless baseline of MOF-2 itself in both directions of forward and reverse temperature scans. These tests revealed that the crosslinker loaded MOF-2 system displays a series of alternate

endothermic and exothermic events successively in the forward temperature scan from ambient to up to 190°C. Similar to the crosslinker loaded MOF-2 system, the reverse of temperature scan direction resulted in a featureless straight line, excluding any possibility of subtle phase changes in the preceding events.

[00273] MOF-1 Loaded with Breaker-Example 1 : Breaking a polymer gel with 1,1- di(tert-butylperoxy)-3,3,5-trimethylcyclohexane.

[00274] 0.6 grams of a guar polymer sample was hydrated in 250 mL of a first tap water sample with a Waring laboratory blender for about 20 minutes while the pH was adjusted with a diluted sodium hydroxide solution to be in the range of 9-10. After that, the pH of the fully hydrated guar solution was further adjusted to approximately a pH of 11. This was followed by adding 1.75 gpt of a crosslinker to crosslink the above formed linear gel. Then, the crosslinked gel was split and placed into separate 50 mL centrifuge tubes with addition of various amounts (4.2 ppt and 5 ppt) of l,l-di(tert-butylperoxy)-3,3,5-trimethylcyclohexane (breaker) loaded into MOF-1, respectively. For the control sample, included 0.2 gpt of breaker alone (not loaded into a MOF). Then, the viscosity profile of the produced samples was probed by Grace M5600 rheometer at 175°F, under a constant shear rate of 100 s^"1 with periodic shear ramping. [00275] FIG. 8 provides an illustration of the rheological profiles observed when 1,1- di(tert-butylperoxy)-3,3,5-trimethylcyclohexane was used to break the linear guar either with or without the MOF carrier. The rheological profiles were obtained on GRACE M5600 rheometers under a 100 s^"1 sheer rate with periodical shear ramping.

[00276] MOF-1 Loaded with Breaker-Example 2: Breaking a polymer gel with 1,1- di(tert-butylperoxy)-3,3,5-trimethylcyclohexane.

[00277] 0.6 grams of a guar polymer sample was hydrated in 250 mL of a second tap water sample with a Waring laboratory blender for about 20 minutes while the pH was adjusted with a diluted sodium hydroxide solution to be in the range of 9-10. After that, the pH of the fully hydrated guar solution was further adjusted to approximately a pH of 11. This was followed by adding 1.75gpt of a crosslinker to crosslink the above formed linear gel. Then, the crosslinked gel was split and placed into separate 50mL centrifuge tubes with addition of various amounts (4.2 ppt and 5 ppt) of l,l-di(tert-butylperoxy)-3,3,5-trimethylcyclohexane (breaker) loaded into MOF-1, respectively. For the control sample, included 0.2 gpt of breaker alone (not loaded into a MOF). Then, the viscosity profile of the produced samples was probed by Grace M5600 rheometer at 175°F, under a constant shear rate of 100 s^"1 with periodic shear ramping.

[00278] FIG. 9 provides an illustration of the rheological profiles observed when 1,1- di(tert-butylperoxy)-3,3,5-trimethylcyclohexane was used to break the linear guar either with or without the MOF carrier. The rheological profiles were obtained on GRACE M5600 rheometers under a 100 s^"1 sheer rate with periodical shear ramping. FIG. 9 shows that the presence of MOF enhances the power of viscosity reduction of the breaker. At equivalent concentrations, the breaker alone does not change the fluid viscosity in any observable extent, but the MOF loaded breaker diminishes fluid viscosity effectively in the optimal time windows.

[00279] MOF-1 Loaded with Breaker-Example 3: Breaking a polymer gel with 1,1- di(tert-butylperoxy)-3,3,5-trimethylcyclohexane.

[00280] 0.6 grams of a guar polymer sample was hydrated in 250 mL of a first tap water sample with a Waring laboratory blender for about 20 minutes while the pH was adjusted with a diluted sodium hydroxide solution to be in the range of 9-10. After that, the pH of the fully hydrated guar solution was further adjusted to approximately a pH of 11. This was followed by adding 1.75gpt of a crosslinker to crosslink the above formed linear gel. Then, the crosslinked gel was split and placed into separate 50mL centrifuge tubes with addition of various amounts (0.8 ppt, 1.6 ppt and 3.2 ppt) of l,l-di(tert-butylperoxy)-3,3,5-trimethylcyclohexane (breaker) loaded into MOF-1, respectively. For the control sample, included 0.2 gpt of breaker alone (not loaded into a MOF). Then, the viscosity profile of the produced samples was probed by Grace M5600 rheometer at 200°F, under a constant shear rate of 100 s^"1 with periodic shear ramping.

[00281] FIG. 10 provides an illustration of the rheological profiles observed when 1,1- di(tert-butylperoxy)-3,3,5-trimethylcyclohexane was used to break the linear guar either with or without the MOF carrier. The rheological profiles were obtained on GRACE M5600 rheometers under a 100 s^"1 sheer rate with periodical shear rates ramping.

[00282] MOF-1 Loaded with Breaker-Example 4: Breaking a polymer gel with sodium bromate.

[00283] 1.2 grams of a guar polymer sample was hydrated in 250 mL of a first tap water sample with a Waring laboratory blender for about 20 minutes while the pH was adjusted with a diluted sodium hydroxide solution to be in the range of 9-10. After that, the pH of the fully hydrated guar solution was further adjusted to approximately a pH of 11. This was followed by adding 3.0gpt of a crosslinker to crosslink the above formed linear gel. Then, the crosslinked gel was split and placed into separate 50mL centrifuge tubes with addition of various amounts (2 ppt, 4 ppt and 5 ppt) of sodium bromate (breaker) loaded into MOF-1, respectively. For the control sample, included 2 ppt of breaker alone (not loaded into a MOF). Then, the viscosity profile of the produced samples was probed by Grace M5600 rheometer at 225°F, under a constant shear rate of 100 s^"1 with periodic shear ramping.

[00284] FIG. 11 provides an illustration of the rheological profiles observed when sodium bromate was used to break the linear guar either with or without the MOF carrier. The rheological profiles were obtained on GRACE M5600 rheometers under a 100 s^"1 sheer rate with periodical shear rates ramping.

[00285] MOF-1 Loaded with Breaker-Example 5: Breaking a polymer gel with 1,1- di(tert-butylperoxy)-3,3,5-trimethylcyclohexane.

[00286] 3.25 ml polyacrylamide polymer in emulsion form was first hydrated in 250 ml of tap water with an overhead mixer at a moderate rate of 500-600 rpm for about 15 minutes. After that, 2.5 gpt of a crosslinker was added into the above linear gel with 10 seconds of mild agitation to achieve the uniform solution, which was then split and placed into 50mL centrifuge tubes. Then, the crosslinked gel was split and placed into separate 50mL centrifuge tubes with addition of various amounts (10 ppt and 15 ppt) of l,l-di(tert-butylperoxy)-3,3,5- trimethylcyclohexane (breaker) loaded into MOF-1, respectively. For the control sample, included 2.5 gpt of breaker alone (not loaded into a MOF). Then, the viscosity profile of the produced samples was probed by Grace M5600 rheometer at 250°F, under a constant shear rate of 100 s^"1 with periodic shear ramping. This experimental data again shows that the presence of MOF enhances the power of viscosity reduction for the breaker.

[00287] FIG. 12 provides an illustration of the rheological profiles observed when 1,1- di(tert-butylperoxy)-3,3,5-trimethylcyclohexane was used to break the linear guar either with or without the MOF carrier. The rheological profiles were obtained on GRACE M5600 rheometers under a 100 s^"1 sheer rate with periodical shear rates ramping.

[00288] Composite MOF-1 Hydrochloric Acid Loading: 2 grams of a powder of MOF-1 were placed in a glass container equipped with a magnetic stirrer bar, and the container was placed on top of a stirring plate equipped with an ice-water bath. Next, 6 mL of a 37% HC1 solution were added drop wise, while stirring. The glass container was covered and agitated for approximately 30 minutes. At the end of the mixing process, the mixture was cooled to a temperature of -40°C and held at this temperature for about 2 hours during which time it froze. While being held at -40°C the frozen mixture was thoroughly blended into an IPC gel, which was prepared at pH 12 with partially hydro lyzed polyacrylamide having a weight average molecular weight of 5 M g/mol and 10% hydrolysis, and with polyvinylpyrrolidone with weight average molecular weight 55k as the non-metallic crosslinker according to the procedures described in U.S. Patent Application Publication No. 2012/0138294. The thoroughly blended mixture was held at -40°C for about 2 hours during which the sample froze. The frozen sample was placed into a Virtis Benchtop Sentry 2.0 (4KZL, SP Scientific) freeze-drier operated at -105°C and 4 mTorr vacuum levels until it was completely freeze dried.

[00289] This procedure was repeated with various IPC gels made with 1% polyacrylamide and 6% polyvinylpyrrolidone or made with 3% polyacrylamide and 6% polyvinylpyrrolidone. [00290] The HC1 concentration in each of the acid-loaded composite MOFs was determined via titration (indicator dye phenolphthalein) of 0.1 gram samples of the various acid- loaded composite MOFs. The results of the titration indicated that the effective HC1 content in the acid-loaded composite MOFs fell in the range of 18-34% HC1 by weight.

[00291] In contrast to a conventional titration involving strong acid and base, where there is a single and irreversible equivalence point, the acid-loaded composite MOFs exhibited a process of delayed, multiple-stage, release of HC1. This multiple-stage, release of HC1 is manifested by reversible color changes observed during the titration experiments, such as when the NaOH was in a slight excess the solution turned from colorless into fuchsia. However, the characteristic fuchsia color faded away over time, which disappeared upon further addition of NaOH.

[00292] Composite MOF-1 to Composite MOF-5 NaOH Loading: 2 grams of each of the respective MOF powders were placed in a container equipped with a magnetic stirrer bar. This was followed by adding a saturated NaOH solution into the container until the MOF sample was fully immersed and the components were mixed for approximately 30 minutes. The slurry was then transferred to a saturation station under approximately 40 mbar vacuum for several days until there were no bubbles in sight and samples were dried. Next, each respective dried mixture was thoroughly blended into an IPC gel, which was prepared at pH 12 with partially hydro lyzed polyacrylamide having a weight average molecular weight of 5 million g/mol and 10% hydrolysis, and with polyvinylpyrrolidone with average molecular weight 55,000 g/mol as the non-metallic crosslinker according to the procedures describe in U.S. Patent Application Publication No. 2012/0138294.

[00293] The thoroughly blended mixture was held at -40°C for about 1 hour during which the sample froze. The frozen sample placed into a Virtis Benchtop Sentry 2.0 (4KZL, SP Scientific) freeze-drier operated at -105°C and 4 mTorr vacuum levels until it was completely freeze dried.

[00294] The NaOH concentration in each of the base-loaded composite MOFs was determined via titration (indicator dye phenolphthalein) of 0.1 gram samples of the various base- loaded composite MOFs. The results of the titration indicated that the effective NaOH content in the base-loaded composite MOFs fell in the range of 16-30% NaOH by weight. [00295] Although only a few example embodiments have been described in detail above, those skilled in the art will readily appreciate that many modifications are possible in the example embodiments without materially departing from the disclosure of METAL ORGANIC FRAMEWORKS AS A CHEMICAL CARRIER FOR DOWNHOLE TREATMENT APPLICATIONS. Accordingly, all such modifications are intended to be included within the scope of this disclosure as defined in the following claims. In the claims, means-plus-function clauses are intended to cover the structures described herein as performing the recited function and not only structural equivalents, but also equivalent structures. Thus, although a nail and a screw may not be structural equivalents in that a nail employs a cylindrical surface to secure wooden parts together, whereas a screw employs a helical surface, in the environment of fastening wooden parts, a nail and a screw may be equivalent structures. It is the express intention of the applicant not to invoke 35 U.S. C. § 112(f) for any limitations of any of the claims herein, except for those in which the claim expressly uses the words 'means for' together with an associated function.

Claims

WHAT IS CLAIMED IS:

1. A fluid for treating a subterranean formation comprising:

a solvent; and

a composition comprising a target chemical entity loaded into a metal organic framework (MOF), wherein the MOF comprises a plurality of pores having a plurality of accessible sites for the reversible uptake of the target chemical entity.

2. The fluid for treating the subterranean formation of claim 1, wherein the MOF comprises at least one bidentate organic compound having a coordinate bond to at least one metal ion.

3. The fluid for treating the subterranean formation of claim 1, wherein the MOF is distributed in a material selected from the group consisting of a polymer particle and an inter- polymer network.

4. The fluid for treating the subterranean formation of claim 1, wherein the target chemical entity is selected from the group consisting of a crosslinker, a breaker, an acid, and a base.

5. The fluid for treating the subterranean formation of claim 2, wherein the target chemical entity comprises at least one functional group, and the least one bidentate organic compound is selected such that the MOF contains complementary functional groups that non- covalently associate with the at least one functional group of the target chemical entity.

6. The fluid for treating the subterranean formation of claim 1, wherein the MOF loaded with the target chemical entity possesses a chemical stability such that less than 1% mass deterioration or decomposition occurs when the MOF loaded with the target chemical entity is exposed to downhole conditions.

7. The fluid for treating the subterranean formation of claim 1, wherein the MOF loaded with the target chemical entity possesses a chemical stability such that less than 1% mass deterioration or decomposition occurs when the MOF loaded with the target chemical entity is exposed to downhole environments for periods greater than a week.

8. A method for treating a subterranean formation comprising:

introducing the fluid of claim 1 or claim 4 into a subterranean formation.

9. The method for treating a subterranean formation of claim 8, wherein the target chemical entity is temporarily stored in the MOF for a duration of from about 30 to about 120 minutes.

10. The fluid for treating the subterranean formation of claim 4, wherein the MOF loaded with the crosslinker possesses a chemical stability such that less than 1% mass deterioration or decomposition occurs when the MOF loaded with the crosslinker is exposed to downhole conditions.

11. The method for treating a subterranean formation of claim 8, further comprising increasing the pH of the fluid by releasing NaOH from an NaOH-loaded MOF; wherein the increase in pH initiates the crosslinking of the crosslinkable component or increasing the viscosity of the fluid upon release of the crosslinker from the crosslinker-loaded MOF, wherein the viscosity of the fluid doubles within 0.5 hours of the release of the crosslinker from the crosslinker-loaded MOF.

12. The method of claim 8, the method further comprising:

reducing the viscosity of the viscosified fluid by at least one order of magnitude by reacting the viscosified fluid with a breaker that has diffused out of the MOF.

13. The method for treating a subterranean formation of claim 12, wherein the breaker is temporarily stored in the MOF for a duration of from about 30 to about 120 minutes before diffusing out of the MOF.

14. The fluid for treating the subterranean formation of claim 1, wherein target chemical entity is an acidizing agent, the acidizing agent being a mineral acid.

15. The fluid for treating the subterranean formation of claim 1, wherein the MOF is a composite MOF in which an acid-loaded MOF is dispersed in a gel comprising greater than 1 wt% polyacrylamide crosslinked with a non-metallic crosslinker, the non-metallic crosslinker comprising a polylactam.

16. The fluid for treating the subterranean formation of claim 14, wherein the MOF loaded with the acidizing agent possesses a chemical stability such that less than 1% mass deterioration or decomposition occurs when the MOF loaded with the acidizing agent is exposed to downhole conditions.

17. The method of claim 8, wherein an acidizing agent is temporarily stored in the MOF for a duration of from about 30 to about 120 minutes.