WO2019173061A1

WO2019173061A1 - Compositions comprising friction reduction polymer particles and methods for use thereof on drilling operations

Info

Publication number: WO2019173061A1
Application number: PCT/US2019/018952
Authority: WO
Inventors: Larry L. Iaccino; Xiaoying Bao
Original assignee: Exxonmobil Chemical Patents Inc.
Priority date: 2018-03-05
Filing date: 2019-02-21
Publication date: 2019-09-12

Abstract

Compositions for decreasing friction may comprise transitional friction reduction polymer particles. At least a portion of the transitional friction reduction polymer particles may be dispersed in solid form under bulk conditions of a drilling operation but liquefy and/or become at least partially solubilized at locations of high friction. Methods for drilling a vvellbore may comprise providing at Ieast one drilling mud composition to a drilling operation and extending a wellbore by drilling in the presence of the at least one drilling mud composition. The at least one drilling mud composition may comprise a plurality of particles comprising at least transitional friction reduction polymer particles, at least a portion of which remain dispersed in solid form in the at least one drilling mud composition under bulk conditions of the drilling operation.

Description

COMPOSITIONS COMPRISING FRICTION REDUCTION POLYMER PARTICLES

AND METHODS FOR USE THEREOF IN DRILLING OPERATIONS

CROSS-REFERENCE TO RELATED APPLICATIONS

[QQQ1] This application claims the benefit of priority from U.S. Provisional Application No 62/638,349, Hied 5 March 2018; and European patent application No. 18168124.8 filed 19 April 2018, which are incorporated herein by reference.

FIELD OF THE INVENTION

[0002] The present disclosure relates to friction reduction within a wellbore and, more specifically, friction reduction using solid friction reduction particles.

BACKGROUND OF THE INVENTION

[0QQ3] Drilling operations within an earthen formation for promoting extraction of a natural resource or a related purpose generally utilize a fluid for removing cuttings from the wellbore, lubricating and cooling the drill bit, controlling formation pressures, and maintaining hole stability . The fluid used in conjunction with drilling a wellbore may be referred to as a “drilling mud” or“drilling fluid.” For the purposes of this disclosure, the terms“drilling mud” and“drilling fluid” also encompass fluids used during other wellbore operations, such as cleaning and completions.

[0004] Certain formations and w'ellbore types may present specific difficulties during drilling operations. Excessive friction while drillin a wellbore can be especially problematic, particularly during horizontal drilling operations, in which both rotational and axial friction may be primary issues. During horizontal drilling operations, it can be difficult to keep the drill string from contacting the wellbore walls and leading to excessive frictional losses. Contact between the drill string and the w'ellbore walls can be particularly prevalent in extended reach drilling (ERD) operations, in which the horizontal section of a wellbore may extend several miles laterally from the entry point in an earthen formation. Excessive friction may lead to equipment damage and/or an inability to continue extending a wellbore to a desired length. Rotational friction also may be problematic in certain situations.

[0005] Various additives may be included in drilling muds to reduce frictional losses. Both liquid and solid friction reduction additives may be used for this purpose.

[0006] Liquid friction reduction additives have been used extensively in drilling muds. However, liquid friction reduction additives may be limited in their friction reduction capabilities, and some may be chemically or thermally unstable under the temperature and pressure conditions frequently present in a wellbore. Without being bound by theory or mechanism, liquid friction reduction additives are believed to function by adsorption onto a metal surface, such as that of the drill string. Liquid friction reduction additives are also typically adsorbed onto the drill cuttings (i.e. , rock particles generated by the drilling process). As such, removal of the drill cuttings from the drilling mud concurrently removes at least a portion of the liquid friction reduction additives from the wellbore, thereby undesirably impacting friction reduction.

[0007] Solid friction reduction additives may exhibit enhanced chemical and thermal stability at wellbore conditions compared to liquid friction reduction additives, but the use of solid friction reduction additives can be problematic in other aspects. US patent application publication 2012/0208725 describes the use of solid wax particles as an additive to drilling fluids for improving lubricity. Whereas such particles can be effective m aqueous drilling fluids, such particles are less stable and therefore less effective in hydrocarbon (oil) based drilling fluids, in particular when using small particle sizes. In hydrocarbon based drilling fluids, a commonly used solid friction reduction additive is graphite. In order to be most effective, such solid friction reduction additives usually need to have a larger particle size than that of the average size of the drill cuttings generated during a drilling operation. Otherwise, the drill cuttings themselves may support the drill string upon the horizontal wellbore wall, in winch case the solid friction reduction additives may provide limited or negligible friction reduction effects. However, if larger friction reduction particles are used, they may be subject to removal by various particle screens intended to remove the drill cuttings from the drilling mud during recirculation to the wellbore. Although solid friction reduction additives may be recovered and recycled from the particle screens and/or fresh solid friction reduction additives may be combined with a drilling mud, these actions are inefficient and may significantly increase the cost and complexity of conducting a drilling operation.

[QQQ8] Despite advances, excessive wellbore friction continues to remain an issue, particularly during ERD operations. As such, new approaches for addressing frictional losses in a wellbore may desirably facilitate various aspects of drilling operations, especially when defining longer wellbores during ERD and other horizontal drilling operations.

SUMMARY OF THE INVENTION

[0009] In some embodiments, the present disclosure provides drilling mud compositions comprising: at least one base drilling mud; and a plurality of particles comprising at least friction reduction polymer particles, also referred to herein as“transitional friction reduction particles' , the transitional friction reduction poly mer particles being substantially dispersed in solid form in the at least one base drilling mud and at least about 50 mass percent of the transitional friction reduction polymer particles remaining dispersed in solid form under bulk conditions of a drilling operation.

[0010] In some embodiments, the present disclosure provides methods for making a drilling mud composition. The methods comprise: providing at least one base drilling mud; and combining a plurality of particles comprising at least transitional friction reduction polymer particles with the at least one base drilling mud, such that at least a portion of the transitional friction reduction polymer particles are substantially dispersed in solid form in the at least one base drilling mud to produce a drilling mud composition with a coefficient of friction less than that of the at least one base drilling mud. The drilling mud composition comprises about 0.1 weight percent (wt. %) to about 20 wt. % transitional friction reduction polymer particles. At least about 50 mass percent (weight percent) of the transitional friction reduction polymer particles remain dispersed in solid form under bulk conditions of a drilling operation.

[0011] In some embodiments, the present disclosure provides methods for conducting a drilling operation. The methods comprise: providing at least one drilling mud composition to a drilling operation, the at least one drilling mud composition comprising a plurality of particles comprising at least transitional friction reduction polymer particles substantially dispersed therein; and extending a wellbore by drilling in the presence of the at least one drilling mud composition. At least about 50 mass percent of the transitional friction reduction polymer particles remain dispersed in solid form in the at least one drilling mud composition under bulk conditions of the drilling operation.

BRIEF DESCRIPTION OF THE DRAWINGS

[0012] The following figure is included to illustrate certain aspects of the present disclosure, and should not be viewed as an exclusive embodiment. The subject matter disclosed is capable of considerable modifications, alterations, combinations, and equivalents m form and function, as will occur to one of ordinary skill in the art and having the benefit of this disclosure.

[0013] The Figure depicts a schemati c of the testing protocol used to determine coefficient of friction in the Examples described below.

DETAILED DESCRIPTION

[0014] The present disclosure relates to friction reduction within a wellbore and, more specifically, friction reduction using solid friction reduction particles.

[0015] As discussed above, friction can be problematic during various wellbore operations, especially drilling operations. Friction reduction additives may aid in decreasing friction within a wellbore, but their use may be problematic. Liquid friction reduction additives may have poor thermal and chemical stability, and they are subject to adsorptive loss on drill cuttings. Solid friction reduction additives can provide better performance under harsh wellbore conditions, but to provide their friction reduction effects, the particle size is typically kept above the average particle size of the drill cuttings generated m the drilling operation. When sized this way, solid friction reduction additives may be subject to sieving by particle screens configured to remove the drill cuttings from the drilling mud prior to recirculation to a wellbore. Sieving results in inefficient use of the solid friction reduction particles and decreased friction reduction performance.

[0016] The present disclosure is directed to friction reduction polymer particles, which may provide significant advantages over solid friction reduction additives conventionally used in drilling operations. Surprisingly, the friction reduction polymer particles described herein may aid in decreasing friction within a wellbore even when the particle size of the friction reduction polymer particles is less than the average particle size of drill cuttings or other particles present within the wellbore. Furthermore, the particles sized in this manner are not significantly removed by particle screens having an effective screening size for removing the drill cuttings. As such, the polymer particles described herein may remain circulating in a wellbore and maintain effectiveness for decreasing friction under conditions where larger solid friction reduction additives are otherwise removed by screening. Although the description herein is primarily directed to decreasing friction (both axial and rotational) in drilling operations, it is to be appreciated that the concepts of the present disclosure may be applicable to other wellbore operations, such as completion operations. Thus, the concepts of the present disclosure may be applied to any wellbore operation where friction reduction is desired.

[0017] The reduction in friction afforded by the friction reduction polymer particles of the present disclosure, also referred to herein as‘transitional friction reduction polymer particles”, is surprising in view of the fact that solid friction reduction additives that are smaller than the average size of the drill cuttings have conventionally provided little to no reduction in friction. Without being bound by any theory or mechanism, it is believed that at least a portion of the transitional friction reduction polymer particles of the present disclosure remain in solid form under bulk wellbore conditions of a drilling operation or other wullbore operation in which friction may be problematic. Upon entering into a location of high friction (/. e. , a high-friction loci), such as a point of interaction between the drill string and the wellbore wall, at least a portion of the transitional friction reduction polymer particles undergo transient exposure to much higher temperature and pressure conditions. The localized higher temperature and pressure conditions are believed to convert the solid polymer particles into a transient liquid within the high-friction loci, thereby allowing the transitional friction reduction polymer particles located outside of the high-friction loci to remain in the solid phase. As such, the present disclosure essentially affords a highly localized placement of a liquid friction reduction additive at a location where it is especially needed (/.<?., at the high-friction loci), even when the transitional friction reduction polymer particles are smaller than the size of the drill cuttings. Since the liquid form of the transitional friction reduction polymer particles is localized and only present transiently, the thermal and chemical stability issues and adsorptive loss issues associated with traditional liquid friction reduction additives may be avoided. Both sliding (axial) friction and/or rotational friction (torque) may be mitigated with the transitional friction reduction polymer particles disclosed herein.

[0018] Moreover, minimal coalescence is believed to take place between isolated pools of the transient liquid formed from the transitional friction reduction polymer particles. As such, once the transient liquid no longer experiences the conditions of high temperature and pressure and undergoes re-solidification, the particle size may remain small enough, or even undergo a reduction in size, so that the transitional friction reduction polymer particles continue circulating in a drilling mud or other wellbore fluid, such as a completion fluid. Therefore, the transitional friction reduction polymer particles of the present disclosure afford advantages commonly associated with both liquid and solid friction reduction additives, without the associated downsides, as previously described.

[0019] The polymers employed in the present disclosure are distinguishable from related, conventional polymers used for decreasing friction in drilling muds while in solubilized form, even polymers bearing similar monomer units. The polymers employed in the transitional friction reduction polymer particles of the present disclosure may be synthesized in a manner to discourage dissolution in a drilling mud or other wellbore fluid, such that at least a portion of the polymer particles remain dispersed m solid form under bulk w¾llbore conditions. In illustrative embodiments, the polymers of the present disclosure may have a sufficiently high molecular weight and/or undergo crosslinking to a sufficient degree to discourage dissolution under bulk wellbore conditions. Once a transient liquid forms from the polymers of the present disclosure at the high-friction loci, the transient liquid may remain as a segregated fluid phase or undergo only partial dissolution in the drilling mud or other wellbore fluid.

[0020] Finally, it is to be further appreciated that transitional friction reduction polymer particles provided at a larger size than the drill cuttings may also function to decrease friction within a wellbore. Provided that the transitional friction reduction polymer particles are smaller than the effective screening size of particle screens, and/or the transitional friction reduction polymer particles undergo a reduction in size prior to contacting the particle screens, the transitional friction reduction polymer particles may still remain circulating in the wellbore. Additional transitional friction reduction polymer particles may be added (either continuously or intermittently) to the wellbore to account for particles lost due to screening, degradation, or like processes.

[0021] All numerical values within the detailed description and the claims herein are modified by“about” or“approximately” with respect to the indicated value, and take into account experimental error and variations that would he expected by a person having ordinary- skill in the art. Unless otherwise indicated, room temperature is about 23°C.

[0022] As used herein, the terms "well" and "wellbore" are used interchangeably and can include, without limitation, an oil, gas, or water production well, an injection well, or a geothermal well As used herein, a "well" includes at least one wellbore. A wellbore can include vertical, inclined, and horizontal portions, and it can be straight, curved, or branched. As used herein, the term "wellbore" includes any cased portion, or any uncased, open-hole portion of the wellbore. A near-wellbore region is the subterranean material and rock of the subterranean formation surrounding the wellbore. As used herein, a "well" also includes the near-w¾llbore region. The near-wellbore region is generally considered to be the region within about 10 feet of the wellbore, although other distances both shorter and longer are also contemplated. As used herein, "into a well" or“into a wellbore” means and includes into ap portion of the well, including into the wellbore or into the near-wellbore region via the wellbore.

[0023] A portion of a wellbore may be an open-hole or cased-hole. In an open-hole wellbore portion, a tubing or drill string may be placed into the wellbore. The tubing or drill string allows fluids to be circulated in the wellbore. In a cased-hole wellbore portion, a casing is placed and cemented into the wellbore, which can also contain a tubing or drill string. The space between two cylindrical shapes is called an annulus. Examples of an annulus include, but are not limited to: the space between the wellbore and the outside of a tubing or drill string in an open-hole wellbore; the space between the wellbore and the outside of a casing in a cased- hole wellbore; and the space between the inside of a casing and the outside of a tubing or drill string in a cased-hole wellbore.

[0024] For purposes of the present disclosure, friction means the mechanical resistance and rubbing of the drill siring with the cased-hole or the open-hole as the drill string or tubing is moved, withdrawn, advanced or rotated. Furthermore friction also comprises the mechanical resistance of coiled tubing inside the cased-hole or the open-hole; introducing casing; introducing screens; introducing tools for cleaning, fracturing, and perforating; rotating drill string; advancing (extending) the wellbore; withdrawing a drill string; and/or withdrawing coiled tubing. For purposes of the present disclosure, drilling operations include the interaction of the drill string with the cased-hole or the open-hole as the drill string or tubing is moved, withdrawn, advanced and/or rotated. Furthermore drilling operations also comprise the movement of coiled tubing inside the cased-hole or the open-hole; introducing casing; introducing screens; introducing tools for cleaning, fracturing, and perforating; rotating the drill string; advancing (extending) the wellbore; withdrawing a drill string; and/or withdrawing coiled tubing.

[QQ25] For the purposes of the present disclosure, the new numbering scheme for the Periodic Table Groups is used. In said numbering scheme, the groups (columns) are numbered sequentially from left to right from 1 through 18, excluding the f-block elements (lanthanides and actinides).

[0026] The person of ordinary skill in the art will recognize that hydroxyl groups on the polymers described herein are subject to deprotonation and may form salts with a suitable counterion. Some suitable counterions include, but are not limited to, Group 1-2 metals, and organic cations (e.g., N(R³)₄ ⁺ and P(R³)T groups), wiiere each R³ group is independently selected from H and hydrocarbyl groups.

[0027] In any embodiment described herein, Group 1-2 metals includes Li, Na, K, Rb, Cs, Fr, Be, Mg, Ca, Sr, Ba, and Ra Particularly suitable Group 1-2 metals may include Li, Na, K, Cs, Mg and Ca.

[0028] The terms "hydrocarbyl radical," "hydrocarbyl," and "hydrocarbyl group," are used interchangeably throughout this document. Likewise, the terms "alkyl radical" and "alkyl" are used interchangeably throughout this document. The terms "group," "radical," and

"substituent" are also used interchangeably in this document. For purposes of this disclosure,

"hydrocarbyl radical" is defined to be any C C_jo radical, that may be linear, branched, or cyclic, and when cyclic, aromatic or non-aromatic. Substituted hydrocarbyl radicals are radicals in which at least one hydrogen atom of the hydrocarbyl radical has been substituted with at least one functional group such as NR₂, OR, SeR, TeR, PR₂, AsR₂, SbR₂, SR, BR₂,

S1R3, GeR3, SnR _ϊ, PbRy, and the like, or where at least one carbon atom of the hydrocarbyl radical has been substituted (replaced) with at least one heteroatom or heteroatom containing functional group. For purposes of this disclosure, "alkyl radical" and interchangeable terms therewith (e.g., "alkyl") are defined to be substituted or unsubstituted aliphatic hydrocarbyl radicals. For the avoidance of doubt, "alkyl radicals" encompass both saturated hydrocarbyl radicals and those having some degree of unsaturation, such as one or more double bonds. Particularly, "alkyl radicals" as used herein may be formed from alkanes, alkenes, and/or alkynes. Examples of such radicals include, but are not limited to, methyl, ethyl, n-propyl, isopropyl, n-butyi, isobutyl, sec-butyl, tert-butyl, pentyl, iso-amyl, hexyl, octyl cyclopropyl, cyclobutyl, cyclopentyl, cyclohexyl, cyclooctyl, and the like, including their substituted analogues. Examples of suitable unsaturated alkyl radicals include, but are not limited to, ethenyl, propenyl, al!yl, 1,4-buiadienyt, cyciopropenyl, cyclobutenyl, cyclopentenyl, cyclohexenyl, cyclooctenyl and the like including their substituted analogues. The term "thioalky!" refers to an alkyl group where at least one carbon atom has been substituted with a sulfur atom.

[0029] The term "aromatic" or "aromatic moiety" refers to a stable mono- or polycyclic, unsaturated moiety, preferably having 3-14 carbon atoms, each of which may be substituted or unsubstituted. Generally, the term "aromatic" or "aromatic moiety" refers to one or more rings, each ring having p-orbitals perpendicular to the plane of the ring at each ring atom and satisfying the Huckel rule. The term "aryl" or "aryl group" means a six carbon aromatic ring and the substituted variants thereof, including but not limited to, phenyl, tolyl, xylyl, and the like. Likewise, the term“heteroaryl” or“heteroaryl group” means an aryl group where a ring carbon atom (or two or three ring carbon atoms) has/have been replaced with a heteroatom, particularly N, O, or S. As used herein, the term "aromatic" also refers to substituted aromatics. Substituted aromatics refer to an aromatic group having at least one hydrogen replaced with a hydrocarbyl group, a substituted hydrocarbyl group, a heteroatom, or a heteroatom-containing group.

[0030] Where isomers of a named alkyl, alkoxide, aromatic, or aryl group exist (e.g., n- butyl, iso-butyl, sec-butyl, and tert-butyl), reference to one member of the group (e.g., n-butyi) shall expressly disclose the remaining isomers (e.g., iso-butyl, sec-butyl, and tert-butyl) in the family. Likewise, reference to an alkyl, alkoxide, aromatic, or aryl group without specifying a particular isomer (e.g. , butyl) expressly discloses all isomers (e.g. , n-buty!, iso-butyl, sec-butyl, and tert-butyl).

[0031] As used herein, a "primary carbon atom" refers to a carbon atom bonded to one carbon atom, a "secondary carbon atom" refers to a carbon atom bonded to two carbon atoms, a "tertiary' carbon atom" refers to a carbon atom bonded to three carbon atoms, and a "quaternary^ carbon atom" refers to a carbon atom bonded to four carbon atoms.

[QQ32] As used herein, the term "cashew nut shell liquid (CNSL)" refers to a liquid extracted from cashew nut shell, m either crude form or a further processed form.

[0033] As used herein, a“polymer” has two or more of the same or different monomer units that are polymerized together with one another, including both homopolymers and copolymers. A“homopolymer” is a polymer having monomer units that are the same. A “copolymer” is a polymer having two or more monomer units that are different from each other. A“terpolymer” is a polymer having three monomer units that are different from each other. “Different” in reference to monomer units indicates that the monomer units differ from each other by at least one atom or are different isomencally. Accordingly, the definition of copolymer, as used herein, includes terpolymers, higher polymers having more than three different monomer units, and the like. In more specific embodiments, suitable polymers for use in the disclosure herein may include at least 100 monomer units that are polymerized together with each other and/or have Mn molecular weight values of at least 100,000.

[QQ34] As used herein, the term“heterogeneous blend” means a composition having two or more morphological phases in the same state. For example a blend of immiscible components (e g., oil and water), where one component forms discrete packets dispersed in a matrix of another component is said to be heterogeneous. By continuous phase is meant the matrix phase in a heterogeneous blend. By discontinuous phase is meant the dispersed phase in a heterogeneous blend. Continuous phases herein may be oil-based or w¾ter-based.

[0035] Throughout this disclosure and the claims appended thereto, transitional friction reduction polymer particles may be described as being“substantially dispersed in solid form in the at least one drilling mud composition under bulk conditions of a/the drilling operation.” Bulk conditions of a drilling operation include, for example, temperatures in the wellbore ranging from a low' of about 50°C, 60°C, 70°C, 80°C, 90°C, 1 G0°C, or 125°C to a high of about 170°C, and pressures ranging from ambient pressure to a high of about 100 bar (10,000 kPa), 200 bar (20,000 kPa), 300 bar (30,000 kPa), 400 bar (40,000 kPa), 500 bar (50,000 kPa), or 600 bar (60,000 kPa). Such hulk conditions may also be referred to herein using the terms “bulk w'ellbore conditions” or“bulk conditions in a wellbore,” for example. Reference to the transitional friction reduction polymer particles being“substantially dispersed in solid form” refers to the condition of at least about 30 mass percent of the transitional friction reduction polymer particles remaining as solids under bulk conditions, or at least about 50 mass percent of the transitional friction reduction polymer particles remaining as solids under bulk conditions, or at least about 80 mass percent of the transitional friction reduction polymer particles remaining as solids under bulk conditions, or at least about 90 mass percent of the transitional friction reduction polymer particles remaining as solids under bulk conditions. [0036] As used herein, the term“transitional friction reduction polymer particles,” refers to a polymeric material that remains substantially dispersed in solid form under bulk conditions in a wellbore (i.e., temperatures <170°C and pressures <600 bar) and forms a transient liquid when one or more of these conditions are exceeded. The skilled person will understand that the particles need not form a transient liquid as soon as these conditions are exceeded, but instead may require temperatures and-'or pressures significantly exceeding the bulk conditions in order to liquefy. Indeed, on locations of high friction during drilling operations where the formation of a transient liquid is desirable, the temperatures and pressures can be much higher than 170°C and 600 bar. Once the transient liquid returns to bulk conditions, the transitional friction reduction polymer particles may re-solidify and thereby reform in particular embodiments, at least 50 wt. %, preferably at least 80 wt. %, most preferably at least 90 wt. % of the transitional friction reduction remains dispersed in solid form in the drilling mud at temperatures below 170°C and pressures below 600 bar, and become liquid at one or more temperatures above i70°C and/or one or more pressures above 600 bar.

[0037] As used herein, the term“liquid friction reduction additive” refers to a substance that exists in a liquid form or a dissolved form or transitions to a liquid form or a dissolved form under bulk conditions in a wellbore.

[QQ38] Kinematic viscosity⁷ (also referred to as“viscosity”) is determined by ASTM D445, and is typically measured at 40°C (Kv40) or 100°C (KvlOO). If temperature is not indicated when specifying a kinematic viscosity, the viscosity is KvlOO.

[0039] Particle sizes expressed herein are Dso values unless otherwise noted.

[0040] According to various embodiments, drilling mud compositions of the present disclosure may comprise at least one base drilling mud, and a plurality⁷ of particles comprising at least transitional friction reduction polymer particles that are substantially dispersed in solid form in the at least one base drilling mud and at least about 50 mass percent of the transitional friction reduction polymer particles remaining dispersed in solid form under bulk conditions of a drilling operation.

[0041] According to various embodiments, the transitional friction reduction polymer particles of the present disclosure may comprise a polymer having a polymerized monomer unit with at least one polar head group and at least one oleophilic tail group. Suitable polar head groups may comprise at least one heteroatom and/or heteroatom functional group. Preferred heteroatoms for the heteroatom and/or heteroatom functional group are heteroatoms selected from the list consisting of N, O, S, and P; more preferably N, O, and S. Illustrative heteroatom functional groups that may be present within the polar head group include, for example, alcohols, phenols, polyols, ethers, polyethers, amines, amides, carboxylic acids, carboxylic esters, nitro groups, sulfones, sulfoxides, sulfonamides, and aldehydes. Suitable oleophilic tail groups may include a hydrocarbyi group, which may be substituted or unsubstituted. In some embodiments, the at least one polar head group and the at least one oleophilic tail group may be incorporated within the same moiety, m which case a separate polar head group need not necessarily be present. For example, when an oleophilic tail group also contains a heteroatom functional group, a separate polar head group need not necessarily be present. A separate polar head group may also be omitted if the backbone of the transitional friction reduction polymer contains a suitable polar heteroatom functionality.

[0042] In more specific embodiments, transitional friction reduction polymer particles of the present disclosure may comprise a polymer having a polymerized monomer unit with a structure defined by Formula 1 below.

Xm— Ar— (R/)n

Formula 1

According to Formula 1, Ar is a single or multi-ring aromatic or heteroaromatic moiety, each X is a polar head group, and each R¹ is an oleophilic tail group that is independently selected from a branched or unbranched, saturated or unsaturated, cyclic or acyclic, substituted or unsubstituted hydrocarbyi group having 1 to about 50 carbon atoms (e.g , a Cs to Cro hydrocarbyi group, a Cio to Cso hydrocarbyi group, a C15 to C?.s hydrocarbyi group, or a Cis to C20 hydrocarbyi group), wherein n is an integer greater than or equal to 1 , and wherein m is an integer greater than or equal to 0 when at least one R¹ is substituted with a heteroatom functional group and/or Ar is a heteroaromatic moiety, and otherwise m is an integer greater than or equal to 1. Each X and each R¹ are the same or different when m or n is greater than 1.

[0043] The polymer may comprise a homopolymer or copolymer comprising the polymerized monomer unit of Formula 1. As one of ordinary skill in the art w ill appreciate, although m and n are each defined as integers, suitable polymers may be prepared from one or more monomers having differing numbers of X and/or R¹ groups. In such embodiments, the average value of m and n per monomer unit within the polymer as a whole may be a non-integer value. Without wishing to be bound by any theory or mechanism, it is believed that the polar head group(s) aid in adsorption of the polymer onto a surface, that the aromatic or heteroaromatic moieties interact to strengthen the adsorbed film, and that the oleophilic tail group(s) aid in forming a lubricant film with nearby adsorbed polymers. Whereas the polymer may be a copolymer, it is preferred that substantially ail co-monomers are monomers according to Formula 1. In particular embodiments, at least 95 wt% of the polymer consists of (co)monomers according to Formula 1, preferably at least 99 wt%, and most preferably 100 wt%.

[0044] In more specific embodiments, Ar is selected from the group consisting of an aryl group, a polynuclear aryl group, a heteroaryl group, a polynuclear heteroaiyl group, a biphenyl group, and a deprotonated cyclic Cs diolefm compound such as cyclopentadienyl. Suitable heteroaryl and polynuclear heteroaryl groups may include, but are not limited to, pyridine, quinoline, isoquinoline, pyrimidine, quinazoline, acridine, pyrazine, quinoxaline, imidazole, benzimidazole, pyrazole, benzopyrazole, oxazole, benzoxazole, isoxazole, benzisoxazole, imidazoline, thiophene, benzothiophene, furan and benzofuran. Suitable polynuclear aryl groups may include, but are not limited to, naphthalene, anthracene, indane, indene, and tetralm. In more specific embodiments, a particularly suitable aromatic moiety may be a phenyl group.

[QQ45] In more specific embodiments, each X is individually selected from the group consisting of -OH (hydroxyl group), -OR² (aikoxy group), -NH2 (amino group), -NHR² or - N(R²)2 (substituted amino group), -NO? (nitro group), -CHO (aldehyde group), -SO2R² (sulfonyl group), -CO2H (carboxyl group), -CO2NH2 (amide group), -CO2NHR² or -CO?N(R²)2 (substituted amide group), -SO2NH2 or -NHSO2R² (sulfonamide group), -SO2NHR², - SO?N(R²)? or -NRSO2R² (substituted sulfonamide group), -SOR² (sulfoxide group), polyamines, polyols, oxazolidines, Group 1-2 metals, N(R²)₄ ⁺ groups, P(R²)₄ ⁺ groups, and a glycosyl group. R preferably is hydrogen or C1-50 hydrocarbyl, more preferably hydrogen or Ci-10 alkyl. In still more specific embodiments, at least one X is -OH or -OCH3. In some embodiments, each X group may have a polarity' ranging between the polarity' of -OCH? and the polarity of -OH.

[0046] Suitable R¹ groups may include methyl or ethyl, as well as branched and unbranched, cyclic and acyclic, isomers of propyl, butyl, pentyl, hexyl, heptyl, octyl, nonyl, decyi, undecyl, dodecyl, tridecyl, tetradecyl, pentadecyl, hexadecyl, heptadecyl, octadecyi, nonadecyl, icosyi, heneicosanediol, docosyl, tricosyl, tetracosyl, and unsaturated variants of any of the foregoing except methyl, particularly wherein the unsaturation is in the form of one or more double bonds. According to more specific embodiments, suitable R^! groups may contain a carbon backbone having at least ten carbon atoms, or at least fifteen carbon atoms. Optionally, one or more R¹ groups can also be comprised of mixtures of alkyl groups, cycloalkyl groups, aromatic groups and other related hydrocarbyl groups.

[0047] The number of carbons atoms adjacent to the a carbon relative to Ar may affect the oxidative stability of the R¹ group, with R¹ groups containing a quaternary a carbon relative to Ar being most stable and R^! groups containing a tertiary a carbon relative to Ar being least stable. Accordingly, branched R¹ groups containing a quaternar ' a carbon relative to Ar (i.e., a quaternary carbon atom directly bonded to Ar) may be present in some embodiments.

[QQ48] According to some embodiments, R¹ may be substituted. In a substituted R¹ group, at least one hydrogen atom of the hydrocarbyl radical may be substituted with a polar functional group selected from the group consisting of -OH, -OR⁴, -NH2, -NHR⁴, -N(R⁴)₂, -NO2 -CHO, - SO2R⁴, -CO2H, -CO2R⁴, -CO2NH2, -CO2NHR⁴, -C0₂N(R⁴)2, -SO2NH2, -NHSO2R⁴, -SO2NHR⁴, -SO -M R ' :· ··. -NRSO2R⁴, -SOR⁴, poh amines polyols, oxazolidines, Group 1 -2 metals, N(R⁴V groups, P(R⁴V groups, and a glycosyl group. R² preferably is hydrogen or C1-50 hydrocarby!, more preferably hydrogen or Ci-10 alkyl. In some embodiments, the polar functional group may be bonded either to the a or b carbon relative to Ar. Alternatively or additionally, at least one carbon atom of the hydrocarbyl radical, which may be the a or b carbon relative to Ar in some embodiments, may be substituted (replaced) with at least one heteroatom or heteroatom-containing functional group. Suitable heteroatoms may include, for example, S (sulfur), O (oxygen), N (nitrogen), and P (phosphorus). Particularly suitable heteroatom containing functional groups may include carbonyl and amide.

[0049] According to some embodiments, the monomer(s) defined by Formula I may comprise multiple X groups and/or multiple R^] groups, such that at least one of m or n is greater than or equal to 2. Thus, according to some embodiments, m may be 2, 3, or 4. Additionally or alternatively, n may be 2, 3, or 4. Generally, monomeris) defined according to Formula 1 may be derived from one or more aromatic compounds and, optionally, one or more co- reagents.

[0050] According to more specific embodiments of the present disclosure, the transitional friction reduction polymer particles may comprise a polymer comprising at least one polymerized monomer unit derived from an alkylphenol or alkylnaphthol. More specifically, according to at least some embodiments, the transitional friction reduction polymer particles may comprise a polymer having at least one polymerized monomer unit that is a hydroxylated aromatic monomer bearing a hydrocarbyl group, wherein the hydrocarbyl group is defined as above for Formula 1.

[0051] According to more specific embodiments of the present disclosure, the transitional friction reduction polymer particles may comprise a polymer that contains one or more polymerized monomer units selected from Formulas 1A-1C, wherein R corresponds to R¹ as defined for Formula 1, and X, m, and n are each

Formula 1A Formula IB Formula 1C

defined the same as above for Formula 1. In more particular embodiments, one or more R groups are located at the meia- or para- position with respect to the X group.

[0052] According to some embodiments, monomers corresponding to Formulas 1, 1 A, I B, or 1C may be synthesized from petroleum-based precursors or derived from naturally occurring sources. In some embodiments, suitable monomers may be formed from one or more monomer precursors. Conversion of a monomer precursor into a polymerizable monomer may take place in situ during polymerization. According to some embodiments, suitable monomers may include, for example, alkylphenols, alkyl anisoles, alkyl naphthols, components of cashew nut shell liquid (CNSL), thioalkylphenols, alkyl benzamides, alkyl anilines, and derivatives of any of the foregoing. Alkylphenols and derivatives thereof may include those having at least ten carbon atoms in the alkyl chain (i.e. , Cio+ alkylphenols). In more specific embodiments, particular monomers according to Formula 1A that may be suitable include, for example, 4- dodecylphenol, 3-pentadecylphenol, and cardanol.

[0053] Particularly suitable monomers and/or classes of monomers according to Formulas 1 A, IB, or 1C are described below. It is to be appreciated, however, that the present disclosure is not limited to polymers formed from these monomer units.

In some embodiments, suitable monomers may be derived from CNSL components.

Suitable components of CNSL, which reside within the scope of Formula LA are represented by Formulas 2-4, wherein w is 0, 2, 4, or 6.

Formula 2 Formula 3 Formula 4

(cardanol) (cardol) (2-methylcardol) [0055] Each of the CNSL components represented by Formulas 2-4 above generally comprises a mixture of compounds with respect to the degree of saturation of the alkyl chain. For example, in some embodiments, each CNSL component may comprise from about 35 wt. % to about 60 wt. % monoene alkyl chains (w-2) based on the total weight of the component, such as from about 45 wt. % to about 50 wt. %; from about 15 wt. % to about 40 wt. % triene alkyl chains (w=6) based on the total weight of the component, such as from about 25 wt. % to about 30 wt. %; from about 10 wt. % to about 20 wt. % diene alkyl chains (w=4) based on the total weight of the component, such as from about 13 wt. % to about 18 wt. %; and from about 3 wt. % to about 10 wt. % saturated alkyl chains (w=0) based on the total weight of the component, such as from about 4 wt. % to about 9 wt. %. CNSL components may be hydrogenated to increase the degree of saturation, thereby increasing the fraction of molecules with w=0 and decreasing the fraction of molecules with w greater than 0. In various embodiments, the fraction of molecules with w=0 may be about 10% or greater, about 50% or greater, about 90% or greater, or about 99% or greater.

[0056] In some embodiments, the transitional friction reduction polymer particles may comprise a copolymer comprising two or more of the CNSL components as polymerized monomer units. Suitable mixtures for forming copolymers of CNSL components may comprise commercial grade CNSL, such as those available from Cardolite Corporation or Palmer International, Inc. Typical mixtures of commercial grade CNSL may comprise from about 50 wt. % to about 80 wt. % eardanoi based on the total weight of the mixture, such as from about 60 wt. % to about 75 wt. %; from 5 wt. % to 15 wt. % cardol based on the total weight of the mixture, such as from about 10 wt. % to about 12 wt. %; and from about 0.5 wt. % to about 5 wt. % 2-methylcardol based on the total weight of the mixture, such as from about 1 wt. % to about 3 wt. %. Additionally or alternatively, suitable mixtures may comprise a ratio of eardanoi to cardol ranging from about 4: 1 to about 15: 1, such as about 6: 1. In some embodiments, mixtures of CNSL components may comprise little to no anacardic acid, such as less than about 5 wt. %, less than about 1 wt. %, or less than about 0.5 wt. % based on the total weight of the mixture.

[0057] Alternatively, the transitional friction reduction polymer particles may comprise a polymer formed from purified eardanoi, cardol, and/or 2-methyl cardol separated from CNSL (e.g., via vacuum distillation or solvent extraction), any of which may be hydrogenated to a fixed or variable degree of unsaturation, according to some embodiments. Examples of suitable commercially available purified eardanoi include NX-2023 and NX-2024, both available from Cardolite Corporation, and 1500-1 and 1500-2 available from Palmer International, Inc. A suitable hydrogenated cardanol product is NC-510, available from Cardolite Corporation.

[0058] In some embodiments, suitable monomers according to any of Formulas 1 A, IB, or 1C may comprise linear alpha olefin (LAO) or poly alpha olefin (PAO) based compounds, particularly functionalized aromatic compounds alkylated with a LAO and/or PAO. For purposes herein, the term "functionalized aromatic compound" refers to an aromatic moiety functionalized with one or more polar functional groups. Suitable functionalized aromatic compounds may include, for example, phenol, anisole, and naphthol, resulting m aJkylphenols, alkyl ani soles, or alkylnaphthols upon alkylation with an LAO or PAO, respectively. The alkylation of the functionalized aromatic compound with the LAO and/or PAO may be performed using known alkylation methods. The alkylation reaction may be catalyzed, such as those utilizing an acid ion-exchange resin or a zeolite. Suitable zeolites may include those that selectively alkylate the aromatic compound in the para- position. Examples of suitable LAO or PAO based compounds may include those represented by Formulas 5-7:

Formula 5 Formula 6

(Ci6 LAO Alkylated Anisole) (C]₄ LAO Alkylated Naphthol)

Formula 7

(C20 PAO Alkylated Anisole)

[0059] In some embodiments, PAOs containing one olefin unsaturation (uPAOs) may be useful for preparing compounds according to Formulas 1A, IB, or 1C. The uPAO may be prepared by oligomerizing a-olefms ranging from carbon numbers of C3 --- C24 and any combination therein. The uPAO oligomer may range from a Mn value of 84 - 7000 Daltons, or carbon numbers of Ce to C500. The uPAO may include dimers, trimers, tetramers, pentamers, and higher oligomers of a-olefms. The oligomerization catalyst used to prepare the uPAO may be the same as any oligomerization catalyst that is known for the preparation ofPAO synthetic lubricant basestocks. Possible examples include metallocene oligomerization catalysts, supported chromium catalysts, or a Lewis acid catalyst, including but not limited to BFs or AlCh catalysts. The unsaturation in the uPAO may have vinylidene, trisubstituted, or vinyl olefin geometry'. Alkylation may generate a new' carbon-carbon bond at a tertiary', secondary-, or primary carbon of the PAO moiety. When alkylation occurs at a tertiary carbon, a quaternary a carbon is generated relative to the aromatic moiety, which may benefit from enhanced oxidative stability. The functionalized aromatic alkylated with the PAO may contain 1 - 5 PAO moieties. The uPAO or the functionalized aromatic alkylated with the PAO may constitute any combination of the variants mentioned herein.

[QQ60] Additional suitable monomers falling within the scope of Formulas 1 and 1A may comprise alkyl benzamides and/or alkylanilines In some embodiments, suitable alkyl benzamides contain a nitro functional group, such as the compounds represented by Formulas 8 and 9.

Formula 8

4-nitro- ' V-octadecy Ibenzami de

Formula 9

(Z)-4-nitro-iV-(octadec-9-en- 1 -y Ijbenzamide

Compounds represented by Formulas 8 and 9 may be synthesized via the amidation of benzoyl chloride with an alkylamine, such as oleylamine. Suitable alkylanilines may include those represented by Formulas 10 and 11, wherein R corresponds to R¹ as defined above for Formula 1 and Y is

Formula 10 Formula 11 a halogen atom, such as bromine. Various procedures are available for synthesizing alkyianilines and will be familiar to one having ordinary skill in the art.

[0061] Additional suitable monomers falling within the scope of Formulas 1 and 1A may comprise thioalkylphenols An example of a suitable thioalkylphenol is BNX 1037, which is defined by Formula 12 and is commercially available from Mayzo, Inc.

Formula 12

2, 4-bis[(dodecylthio)methyl]-6-methy 1-phenol

[QQ62] Monomers falling within the scope of Formulas 1 and 1 A may be derivatives of any of the above-described aromatic monomers, such as derivatives formed from a!ky!pheno!s. Suitable cardanol derivatives, for example, may include animated cardanols (e.g., phenalkamines), polyols and Mannich base precursors thereof, nitrated cardanols, sulfonated cardanols, and glycosyl-modified cardanols. Similar derivatives may be formed from alkylphenols apart from cardanol.

[0063] Suitable aminated cardanols may be synthesized via the Mannich base reaction between cardanol, an aldehyde (e.g., formaldehyde), and an amine. Aminated cardanols may include phenalkamines (/ <?., compounds wherein the amine used to form the amininated cardanol is a polyamine, such as ethylenediamine or diethyltriamme). An example of a suitable commercially available phenalkamme is RAC-951LV, available from Palmer International Inc. and having Formula 12, wherein w is 0, 2, 4, or 6. Additional examples of

Formula 13

suitable aminated cardanols are depicted in Formulas 14-16, wherein w is 0, 2, 4, or 6.

Formula 16

[0064] Suitable polyol derivatives may comprise at least two hydroxy] groups, such as two, three, or four hydroxyl groups. Suitable polyols may be synthesized by procedures familiar to a person having ordinary skill in the art. Formula 17 below shows an illustrative diol derivative of cardanoi that may be suitable for use in the embodiments described herein.

Formula 17

wherein w is 0, 2, 4, or 6. Glycosyl derivatives of cardanoi and other alkylphenols may also be suitable in the embodiments of the present disclosure. Formula 18 shows an illustrative glycosyl-modified cardanoi that may be suitable,

Formula 18

wherein w is 0, 2, 4, or 6. Glycosyl-modified cardanols of the structure illustrated above may be synthesized by reacting cardanoi with glucose pentaacetate in the presence of a Lewis acid, such as boron trifluoride diethyl etherate

[0065] Suitable polymers comprising a monomer defined by any of the Formulas above may be linear, branched or cyclic and are not limited by any particular structure, provided that the polymer remains substantially dispersed in solid form under bulk conditions in a wellbore. Suitable polymers may have any number of repeat units and are not limited by any particular molecular weight range, provided that the polymer is capable of remaining substantially dispersed in solid form under bulk conditions in the wellbore. At least about 30 mass percent, or at least about 50 mass percent, or at least about 70 mass percent, or at least about 80 mass percent, or at least about 90 mass percent, or at least about 95 mass percent of the transitional friction reduction polymer particles may remain dispersed as solids in the embodiments described herein.

[0066] Suitable polymers may be synthesized from petroleum-based monomers or from monomers obtained or derived from naturally occurring sources. As one of ordinary skill in the art will appreciate, the polymerization process may be carried out in the presence of a catalyzing agent and/or under the action of heat. Suitable polymerization processes may include, for example, addition or condensation polymerization. Catalyzing agents suitable for conducting each type of polymerization process will be familiar to one having ordinary' skill in the art.

[0067] Suitable polymers useful in the drilling mud compositions of the present disclosure may be synthesized via condensation polymerization, according to some embodiments. Particularly, suitable polymers may comprise a condensation reaction product of one or more monomers represented by at least one of the Formulas above with a co-reagent. Suitable co reagents include those capable of providing a methylene or substituted methylene bridge (linker) between one or more of the monomer units defined according to the Formulas above, particularly forming a linkage between the aromatic or hetereoaromatic ring of each monomer unit. Suitable co-reagents may include, for example, ketones, aldehydes, and amines. Acetone may be a particularly suitable ketone. Suitable aldehydes may include formaldehyde (including formaldehyde oligomers and polymers such as paraformaldehyde and 1,3,5-trioxane), furfural, and branched or unbranched C?.+ alkyl aldehydes (i.e. , alkyl aldehydes having two or more carbon atoms). In some embodiments, C2₊ alkyl aldehydes may be produced via hydroformylation of C2+ olefins, such as long chain alkyl aldehydes, such as C10+ alkyl aldehydes. Suitable amines may include hexamethylenetetramine (hexamine) and 1,2- ethanediamme (ethylenediamine).

[QQ68] In some embodiments, suitable condensation polymers may be formed using phenol as a starting material. In certain embodiments, alkylphenol monomers according to Formula 1 A, for example, may be generated in situ during the course of a condensation polymerization process from the condensation of phenol and a co-reagent. The alkylphenol monomers may continue to undergo subsequent condensation polymerization.

[0069] Illustrative condensation polymers may include bisphenols and phenolic resins comprising the condensation reaction product of an alkylphenol with formaldehyde, such as those formed from cardanol or 4-nonylphenol. In some embodiments, suitable condensation polymers may be novolac resins, which are phenolic resins formed from condensation of formaldehyde with an alkylphenol at a molar ratio of less than one under acid catalyst conditions. Examples of suitable novolac resins for use in the present disclosure include Bakelite™ Resin PF6920CL and Bakelite^IMResin PF7601CLCL, both commercially available from Hexion Inc. Suitable novolac resins synthesized from cardanol or hydrogenated cardanol are available from Plenco, one example of which is PLENCO 15332.

[0070] Suitable polymers for inclusion in the drilling mud compositions of the present disclosure may also be synthesized via addition poly merization, such as polymers obtained by thermal polymerization routes. Addition polymerization may be particularly suitable for forming polymers from one or more monomers having at least one unsaturated R group present in the monomer unit. In such embodiments, the polymerization process proceeds via bond formation at the location of the unsaturation in each monomer unit.

[0071] In some embodiments, addition polymers may be formed from one or more alkylphenol monomers, such as cardanol. For example, an illustrative polymer may comprise thermally polymerized cardanol, which may be thermally polymerized by heating to a temperature of at least 100°C, at least 150°C, or at least 200°C. The cardanol may be provided in a decarboxylated CNSL or in a purified cardanol stream derived therefrom. Optionally, the thermal polymerization of cardanol or other suitable monomers may be catalyzed using alkalis, acids, or naturally occurring salts, including those present m a CNSL.

[QQ72] Additional suitable polymers useful in the drilling mud compositions of the present disclosure may include polyanilines synthesized from monomers of the types represented by Formulas 1 A- 1C, in which X is NR . Polymerization may occur via oxidative polymerization. Illustrative polymers may have Formulas 19 or 20 below',

Formula 19 Formula 20 wherein R may be a substituent as defined as above for R¹ in Formula 1 and n is an integer of greater than 1 Suitable oxidative polymerization processes will be familiar to one having ordinary' skill in the art.

[0073] Suitable polymers for the drilling mud compositions described herein may be optionally crosslinked. Crosslinked polymers may be formed by reacting a crosslinking agent with one or more monomers defined by the Formulas above, or a polymer formed therefrom, in which at least one unsaturated R or R¹ group is present. In some embodiments, crosslinking may take place between heteroatoms, such as hydroxyl groups, on adjacent polymer chains. Intramolecular crosslinking may take place in some instances as well. The crosslinking agent is generally a low molecular weight (typically between a lower molecular weight of about 50 to 100 g/mole to an upper molecular weight of about 200 or 400 g/mole), bi-functional compound capable of forming covalent bonds. The crosslinking agent may form a linkage between adjacent polymer chains (or mtramolecularly) through the unsaturated bonds of the R group of the two or more monomers, or by forming bonds to a heteroatom. In more specific embodiments, suitable crosslinking agents may include at least one of oxygen, nitrogen, sulfur, or silicon. Suitable crosslinking agents include, but are not limited to, sulfur chloride, chtoroperbenzoic acid, formaldehyde, diamines, diacids, bis-epoxides, halohydrins, diols, and silanes (e.g., 1,1 ,3,3,-tetramethyldisiloxane). For example, according to some embodiments, suitable polymers may comprise a silane-crosslinked polymer containing an alky!pheno! monomer, such as a cardanol monomer.

[0074] The transitional friction reduction polymer particles described hereinabove may be included a drilling mud in any suitable amount. In some embodiments, the drilling muds described herein by comprise between about 0.1 wt. % to about 20 wt. % of the transitional friction reduction polymer particles. In more specific embodiments, the transitional friction reduction polymer particles may be present in an amount ranging between about 0.5 wt. % to about 20 wt. %, or between about 1 wt. % to about 20 wt. %, or between about 1 wt. % to about 15 wt. %, or between about 2.5 wt. % to about 15 wt. %, or between about 5 wt. % to about 20 wt. %, or between about 5 wt. % to about 15 wt. %, or between about 5 wt. % to about 10 wt. %, or between about 10 wt. % to about 20 wt. %, or between about 10 wt. % to about 15 wt. %.

[0075] According to some embodiments, the drilling mud compositions of the present disclosure may further comprise at least one liquid friction reduction additive. As used herein, the term‘liquid friction reduction additive” refers to a friction reduction compound that is liquid form or is at least partially dissolved in liquid form in a base drilling mud under bulk conditions of a drilling operation. Thus, as used herein, the term‘liquid friction reduction additive” refers to substances that are at least partially soluble in and/or exist in the liquid state as a heterogeneous blend in a drilling mud at bulk conditions within a wellbore.

[0076] In some embodiments, the at least one liquid friction reduction additive may comprise a cashew nut shell liquid. Any component of cashew nut shell liquid, derivatives thereof, or mixtures thereof may be suitable for use as the at least one liquid friction reduction additive. In particular embodiments, the at least one liquid friction reduction additive may comprise cardanol, cardo!, 2-methyl cardol, any derivative thereof, or any mixture thereof, optionally in further combination with other component(s) of cashew nut shell liquid. In still more particular embodiments, the at least one liquid friction reduction additive may comprise cardanol.

[0077] In some or other embodiments, the at least one liquid friction reduction additive may comprise selachyl alcohol, the structure of which is shown m Formula 21 below.

Formula 21

Other molecules having the same glycerol-based polar head group but different oleophilic tail groups may be used similarly and/or in combination with selachyl alcohol. According to some embodiments, selachyl alcohol may be present as the at least one liquid friction reduction additive in combination with a cashew nut shell liquid, such as cardanol.

[QQ78] Other suitable liquid friction reduction additives may include, for example, amphiphilic compounds such as, for example, fatty acids, fatty acid esters, fatty acid amides, fatly alcohols, and fatly amines. Illustrative examples may include, for example, oleic acid, oleyl amide, glycerol monooleate, and bis-(2-hydroxyethyl)alkylamines.

[0079] Still other suitable liquid friction reduction additives may include, for example, nitrogen-containing compounds; esters; substituted imidazolines and amides, such as those described in U.S. Patent Application Publication 2017-0002252; hydrocarbyl dio!s containing Cio to Ci alkyl groups, such as those described in U.S. Patent Application Publication 2017- 0002254; glycerol carbamates, such as those described in U.S. Patent Application Publication

2017-0002251; hydrocarbyl thioglycerols, such as those described in U.S. Patent Application

Publication US 2017-0002250; phosphate esters and dihydrocarbyl hydrogen phosphites, such as those described in U.S. Patent Application Publication 2017-0002253; and hydrocarbyl aromatic compounds having at least one polar functional group, such as soluble alkylphenols.

[0080] Commercially available liquid friction reduction additives that may be suitable for use m the embodiments of the present disclosure include, for example, Vikinol™ 18, ColaLube™ 3410, ColaLube™ 3407, and additives under the tradename CoiaMid™.

[QQ81] Liquid friction reduction additives may be present in the drilling mud compositions of the present disclosure in any suitable amount. In illustrative embodiments, the at least one liquid friction reduction additive may be present in an amount up to about 10 wt. %, or up to about 5 wt.%, or up to about 1 wt. %, or up to about 0.5 wt. %, or up to about 0 1 wt. %. Amounts both above and below the foregoing ranges, as well as any subrange thereof, are also contemplated by the present disclosure, which includes embodiments m which liquid friction reduction additives are absent from the drilling mud compositions disclosed herein.

[QQ82] According to some embodiments, drilling mud compositions of the present disclosure may comprise at least one base drilling mud that comprises an oil-based mud. In other embodiments, drilling mud compositions of the present disclosure may comprise at least one base drilling mud that comprises a water-based mud. It is to be recognized that the term “oil-based” or“water-based” refers to the predominant continuous phase in the drilling mud. Specifically, an oil-based mud contains a hydrocarbon or“oil” continuous (external) phase, and a water-based mud contains an aqueous or“water” continuous (external) phase. The transitional friction reduction polymer particles or any other components of the drilling muds may be emulsified in the drilling mud compositions with either type of base mud. In the case of an oil-based mud, the transitional friction reduction polymer particles or other components may be contained within a discontinuous (internal) phase comprising an aqueous liquid. In the case of a water-based mud, the transitional friction reduction polymer particles or other components may be contained within a discontinuous (internal) phase comprising an oleaginous (oily) liquid. Inversion of either type of emulsion may release the transitional friction reduction polymer particles to aid in decreasing friction at high-friction loci.

[0083] Oil-based muds may include a base oil and one or more base oil additives. According to some embodiments, the at least one base drilling mud may lack or substantially lack the transitional friction reduction polymer particles prior to forming the drilling mud composition. In some or other embodiments, the transitional friction reduction polymer particles may be combined with a first portion of the at least one base drilling mud to form a first drilling mud composition, and the first drilling mud composition can be combined with a second portion of the at least one base drilling mud to form the drilling mud composition containing the transitional friction reduction polymer particles dispersed in solid form. Combining the first drilling mud composition with the second portion of the at least one base drilling mud may take place in a wellbore, according to some embodiments.

[QQ84] Numerous base oils are known in the art. Particular base oils that are useful in the present disclosure include natural oils and synthetic oils, as well as unconventional oils (or mixtures thereof), which can be used unrefined, refined, or re-refined (the latter is also known as reclaimed or reprocessed oil). Unrefined oils are those obtained directly from a natural or synthetic source and used without added purification. These include shale oil obtained directly from retorting operations, petroleum oil obtained directly from primary distillation, and ester oil obtained directly from an esterification process. Refined oils are similar to the oils discussed for unrefined oils except refined oils are subjected to one or more purification steps to improve at least one base oil properly, which will be familiar to one having ordinary skill in the art. Suitable purification processes may include solvent extraction, secondary distillation, acid extraction, base extraction, filtration, and percolation. Re-refined oils are obtained by processes analogous to refined oils but using an oil that has been previously used as a feed stock.

[Q085] Groups I, II, III, IV, and V are broad lube base oil stock categories developed and defined by the American Petroleum Institute (API Publication 1509; www.API.org) to create guidelines for base oils. Group I base stocks have a viscosity index of 80 to 120 and contain > 0.03% sulfur and/or less than 90% saturates. Group II base stocks have a viscosity index of 80 to 120, and contain < 0.03% sulfur and > 90% saturates. Group III stocks have a viscosity index > 120 and contain < 0.03% sulfur and > 90% saturates. Group IV includes polyaiphaoiefins (PAG) and Gas-to-Liquid (GTL) materials. Group V base stock includes base stocks not included in Groups I-IV. Table 1 below summarizes properties of each of these five groups.

Table 1 : Exemplary Base Oil Properties

[0086] Natural oils include animal oils, vegetable oils (castor oil and lard oil for example), and mineral oils. Animal and vegetable oils possessing favorable thermal oxidative stability can be used. Mineral oils vary widely as to their crude source, for example, as to whether they are paraffinic, naphthenic, or mixed paraffinic-naphthenic. Oils derived from coal or shale are also useful. Natural oils vary also as to the method used for their production and purification, for example, their distillation range and whether they are straight run or cracked, hydrorefined, or solvent extracted. Group ΪΪ and/or Group III hydroprocessed or hydrocracked basestocks, including synthetic oils, are also well known base oils.

[0087] Synthetic oils include hydrocarbon oil. Hydrocarbon oils include oils such as polymerized and interpolymenzed olefins (polybutylenes, polypropylenes, propylene isobutylene copolymers, ethylene-olefin copolymers, and ethylene-alphaolefin copolymers, for example). Poiyaiphaolefm (PAG) oil base stocks are commonly used synthetic hydrocarbon oil. By way of example, PAOs derived from Cs to Ci4 olefins (e.g., Cs, Cio, C12, CM olefins or mixtures thereof) may be utilized.

[0088] The number average molecular weights of the PAOs, which are known materials and generally available on a major commercial scale from suppliers such as ExxonMobil Chemical Company, Chevron Phillips Chemical Company, BP, and others, typically vary from 250 to 3,000 g/mol, although PAO's are typically made in kinematic viscosities up to 3,500 cSt (100°C). The PAOs are typically comprised of relatively low molecular weight hydrogenated polymers or oligomers of alphaolefins which include, but are not limited to, C2 to C32 alphaolefins such as poly-l-octene, poly-l-decene, poly-l-dodecene, mixtures thereof, and mixed olefin-derived polyolefins. However, the dimers of higher olefins in the range of Ci4 to Ci8 may be used to provide low viscosity basestocks of acceptably low volatility. Depending on the viscosity grade and the starting oligomer, the PAOs may be predominantly trimers and/or tetramers of the starting olefins, with minor amounts of the higher oligomers, having a kinematic viscosity range of 1.5 to 3,500 cSt (KvlOO), such as from 1.5 to 12 cSt.

[QQ89] Other useful fluids for use as base oils include non-conventional or unconventional base stocks that have been processed, such as catalytically, or synthesized to provide high performance characteristics. Non-conventional or unconventional base oils include one or more of a mixture of base stock(s) derived from one or more Gas-to-Liquids (GTL) materials, as well as isomerate/i sodewaxate base stock(s) derived from natural wax or waxy feeds, mineral and or non-mineral oil waxy feed stocks such as slack waxes, natural waxes, and waxy stocks such as gas oils, waxy fuels hydrocracker bottoms, waxy raffinate, hydrocrackate, thermal crackates, or other mineral, mineral oil, or even non-petroleum oil derived waxy materials such as waxy materials received from coal liquefaction or shale oil, and mixtures of such base stocks

[0090] GTL materials are materials that are derived via one or more synthesis, combination, transformation, rearrangement, anchor degradation/deconstructive processes from gaseous carbon-containing compounds, hydrogen-containing compounds and/or elements as feed stocks such as hydrogen, carbon dioxide, carbon monoxide, water, methane, ethane, ethylene, acetylene, propane, propylene, propyne, butane, butylenes, and butynes. GTL base stocks and/or base oils are GTL materials of base oil viscosity that are generally derived from hydrocarbons; for example, waxy' synthesized hydrocarbons, that are themselves derived from simpler gaseous carbon-containing compounds, hydrogen-containing compounds and/or elements as feed stocks. GTL base stock(s) and/or base oil(s) include oils boiling in the lube oil boiling range (1) separated/fractionated from synthesized GTL materials, such as, for example, by distillation and subsequently subjected to a final wax processing step, which involves either or both of a catalytic dewaxing process, or a solvent dewaxing process, to produce lube oils of reduced/low pour point: (2) synthesized wax isomerates, comprising, for example, hydrodewaxed or hydroisomerized cat and/or solvent dewaxed synthesized wax or waxy hydrocarbons; and (3) hydrodewaxed or hydroisomerized cat and/or solvent dewaxed Fischer-Tropsch (F-T) material (/.<?., hydrocarbons, waxy hydrocarbons, waxes and possible analogous oxygenates), such as hydrodewaxed or hydroisomerized/followed by catalytic and/or solvent dewaxing, dewaxed F-T waxy hydrocarbons, or hydrodewaxed or hydroisomerized/followed by catalytic or solvent dewaxing, dewaxed F-T waxes, or mixtures thereof.

[0091] GTL base stock(s) and/or base oil(s) derived from GTL materials, especially, hydrodewaxed or hydroisomerized/followed by catalytic and/or solvent dewaxed wax or waxy feed, such as F-T material derived base stock(s) and/or base oil(s), are characterized typically as having kinematic viscosities at 100°C of about 2 cSt to 50 cSt as meas ured by ASTM D445. They are further characterized typically as having pour points of about -5°C to -40°C or lower as measured by ASTM D97. They are also characterized typically as having viscosity indices of about 80 to 140 or greater as measured by ASTM D2270.

[0092] In addition, the GTL base stock(s) and/or base oil(s) are typically highly paraffinic (>90% saturates), and may contain mixtures of monocycloparaffins and multicycloparaffins in combination with non-cyclic isoparaffins. The ratio of the naphthenic (i.e. , cycloparaffin) content in such combinations varies with the catalyst and temperature used. Further, GTL base stock(s) and/or base oil(s) typically have very low sulfur and nitrogen content, generally containing less than 10 ppm, and more typically less than 5 ppm of each of these elements. The sulfur and nitrogen content of GTL base stock(s) and/or base oil(s) obtained from F-T material, especially F-T wax, may be essentially nil. In addition, the absence of phosphorous and aromatics make this materially especially suitable for the formulation of low SAP products.

[0093] The term GTL base stock and/or base oil and/or wax isomerate base stock and/or base oil is to be understood as embracing individual fractions of such materials of wide viscosity range as recovered in the production process, mixtures of two or more of such fractions, as well as mixtures of one or two or more low viscosity fractions with one, two or more higher viscosity fractions to produce a blend wherein the blend exhibits a target kinematic viscosity.

[QQ94] The GTL material, from which the GTL base stock(s) and/or base oil(s) is/are derived may be an F-T material (/.<?., hydrocarbons, w⁷axy hydrocarbons, or wax). In addition, the GTL base stock(s) and/or base oil(s) are typically highly paraffinic (>90% saturates), and may contain mixtures of monocycloparaffins and multicycloparaffins in combination with non- cyclic isoparaffins. The ratio of the naphthenic (/ <?., cycloparaffin) content in such combinations varies with the catalyst and temperature used. Further, GTL base stock(s) and/or base oil(s) and hydrodewaxed, or hydroisomerized/catalytic (and/or solvent) dewaxed base stock(s) and/or base oil(s) typically have very low sulfur and nitrogen content, generally containing less than 10 ppm, and more typically less than 5 ppm of each of these elements. The sulfur and nitrogen content of GTL base stock(s) and/or base oil(s) obtained from F-T material, especially F-T wax, may be essentially nil. In addition, the absence of phosphorous and aromatics make this material especially suitable for the formulation of low sulfur, sulfated ash, and phosphorus (low SAP) products.

[0095] Base oils for use in the formulated oil-based mud compositions useful in the present disclosure are any of the variety of oils corresponding to API Group I, Group 11, Group III, Group IV, and Group V oils, and mixtures thereof, particularly API Group II, Group III, Group IV, and Group V oils, and mixtures thereof, due to their exceptional volatility, stability, viscometric and cleanliness features. Minor quantities of Group I stock, such as the amount used to dilute additives for blending into formulated lube oil products, can be tolerated m minimal amounts, such as their use as diluents/ carrier oil for additives used on an "as-received" basis. Group IT stocks may have a viscosity index in the range of 100 to 120, according to some embodiments.

[0096] Some base oils may have an ester content of about 50 wt. % or less, about 40 wt. % or less, about 30 wt.% or less, about 5 wt. % or less, or about 1 wt. % or less. Additionally or alternatively, some base oils may have an ester content of about 40 wt. % or greater, or about 50 wt. % or greater, about 70 wt. % or greater, or about 90 wt. % or greater

[0097] Some base oils may have an aromatic content ranging from about 0.005 wt. % to about 15 wt. %, about 0.01 wt. % to about 10 wt. %, about 0.05 wt. % to about 5 wt. %, or about 0.1 wt. % to about 1 wt. %.

[QQ98] Some base oils have been characterized by their Kinematic viscosity at 40°C (Kv40). For example, particular base oils may have a viscosity of about 1.0 cSt or greater, about 1.3 cSt or greater, about 1.5 cSt or greater, about 1.7 cSt or greater, about 1.9 cSt or greater, about 2.1 cSt or greater, about 2.3 cSt or greater, about 2.5 cSt or greater, about 2.7 cSt or greater, about 2.9 cSt or greater, about 3.1 cSt or greater, about 3.3 cSt or greater, about 3.5 cSt or greater, about 3.7 cSt or greater, about 4.0 cSt or greater, about 4.5 cSt or greater, or about 4.8 cSt or greater at 40°C. Additionally or alternatively, the viscosity at 40°C may be about 5.0 cSt or less, about 4.8 cSt or less, about 4.5 cSt or less, about 4.0 cSt or less, about 3.7 cSt or less, about 3.5 cSt or less, about 3.3 cSt or less, about 3.1 cSt or less, about 2.9 cSt or less, about 2.7 cSt or less, about 2.5 cSt or less, about 2.3 cSt or less, about 2.1 cSt or less, about 1.9 cSt or less, about 1.7 cSt or less, about 1.5 cSt or less, about 1.3 cSt or less, or about 1.1 cSt or less, at 40°C. Some such base oils are available from ExxonMobil Chemical Company under the tradename ESC AID™. ESCAID™ 110, for example, comprises a desulfurized hydrogenated hy drocarbon containing less than 0.50 wt. % aromatics and having a viscosity of about 1.7 cSt at 40°C. ESCAID™ 115, for example, comprises a viscosity of about 2.1 cSt at 40°C. ESCAID™ 120, for example, comprises a flash point above 100°C, and ESCAID™ 120 ULA has an aromatics content < 0.01 wt. %.

[0099] Water-based muds may include an aqueous carrier fluid, such as fresh water, salt water, sea water, or brine, optionally containing a w'ater-miscible organic co-solvent such as an alcohol or glycol. As used herein, the term“brine” refers to a saturated aqueous salt solution. Brines may increase the weight of a drilling mud composition, which can be advantageous for maintaining hydrostatic pressure in a wellbore. Illustrative weights may include a range of about 5 pounds per gallon (ppg) to about 20 ppg, or about 10 ppg to about 16 ppg. Suitable brines may include, for example, sodium chloride brines, sodium bromide brines, potassium chloride brines, potassium bromide brines, magnesium chloride brines, calcium chloride brines, and calcium bromide brines. Oil can also be emulsified in the aqueous carrier fluid, according to some embodiments. In other embodiments, aqueous carrier fluids and water- based muds formed therefrom may be free or essentially free from oil or oil components. Suitable emulsifying agents and/or surfactants may be present, in some embodiments. [0100] Suitable water-based muds may include, for example, BARASHALE, HYDRO- GUARD, or PERFORMADRIL, which are available from Halliburton Energy Services, Inc.; PERFORMAX, PER-FLEX, TERRA-MAX, PYRO-DRILL, or MAX-BRIDGE, which are available from Baker-Hughes, Inc.: or DRILPEX, D URATHERM, ENVIROTHERM NT, KLA-SHIELD, or ULTRADRIL, which are available from Schiumberger.

[0101] Drilling mud compositions of the present disclosure may also include further additives. The further additives may form a heterogeneous blend with a base oil or an aqueous carrier fluid. For either oil-based or wnter-based drilling mud compositions, the further additives may be dispersed in either the external phase or the internal phase of the drilling mud compositions. Additional additives that may be suitable include, but are not limited to, an acid, a base, a pH buffer, a viscosifier and/or a rheology modifier, an emulsifier, a wetting agent, a weighting agent, a fluid loss additive, and a friction reducer.

[0102] Illustrative pH buffers and bases may be selected from the group consisting of magnesium oxide, potassium hydroxide, calcium oxide, and calciu hydroxide. Lime is a commercially available example. The pH buffer or base can be present in a concentration m the range of about 0.5 to about 10.0 pounds per barrel (ppb) of the drilling mud composition. The pH may range from a low of about 7, 8, 9, 10, 1 1, or 12 to a high of about 14, such as from 10 to 14.

[0103] Suitable viscosifiers and rheology modifiers may be selected from the group consisting of inorganic viscosifiers, fatty acids, including but not limited to dimer and trimer poly carboxylic fatty acids, diamines, polyamines, organophilic clays and combinations thereof. Commercially available examples of suitable viscosifiers include, but are not limited to, VG-PLUS™, available from M-I SWACO; and RHEMOD L™, TAU-MOD™, RM-63™, and combinations thereof, marketed by Halliburton Energy Services, Inc. According to some embodiments, the viscosifier and/or rheology modifier may be present in a concentration of at least 0.5 ppb of the drilling mud composition. In more specific embodiments, the viscosifier and/or rheology modifier can also be present in a concentration of about 0 5 ppb to about 20 ppb, or a range of about 0.5 ppb to about 10 ppb, of the drilling mud composition.

[0104] The drilling mud compositions may further include a solid lubricant in addition to the transitional friction reduction particles and/or the liquid friction reducers described elsewhere herein. In particular embodiments, the solid lubricant may comprise a particulate material, for example, a graphite such as STEELSEAL™, available from Halliburton Energy- Services, Inc.

[0105] The drilling mud compositions can further include an emulsifier. The emulsifier can be selected from the group consisting of tall oil-based fatty acid derivatives such as amides, amines, arnidoamines, and imidazolines made by reactions of fatty acids and various ethanolamine compounds, vegetable oil-based derivatives, and combinations thereof. Commercially available examples of a suitable emulsifier include, but are not limited to, EZ MUL™ NT, INVERMUL™ NT, LE SUPERMUL™, and combinations thereof, marketed by Halliburton Energy Services, Inc,, MEGAMUL™, VERSAMUL™, VERSACOAT™, marketed by MI-SWACO. According to some embodiments, the emulsifier is in at least a sufficient concentration such that the drilling mud composition maintains a stable emulsion or an invert emulsion. According to more specific embodiments, the emulsifier is in a concentration of at least 1 ppb of the drilling mud composition. The emulsifier can also be in a concentration in the range of about 1 to about 20 ppb of the drilling mud composition.

[0106] The drilling mud composition can further include a weighting agent. In some embodiments, the weighting agent can be selected from the group consisting of barite, hematite, manganese tetroxide, calcium carbonate, and combinations thereof. Commercially available examples of suitable weighting agents include, but are not limited to, BAROID™, B ARACARB™, BARODENSE™, and combinations thereof, marketed by Halliburton Energy Services, Inc. and MICROMAX™, marketed by Elkem According to some embodiments, the weighting agent may be present in a concentration of at least 10 ppb of the drilling mud composition. Tire weighting agent can also be present m a concentration in the range of about 10 to about 1000 ppb, such as 10-800 ppb, of the drilling mud composition.

[0107] The drilling mud compositions can further include a fluid loss additive. In some embodiments, the fluid loss additive can be selected from the group consisting of oleophilic polymers, including crosslinked oleophilic polymers and particulates. Commercially available examples of suitable fluid loss additives include, but are not limited to, VERSATROL™, available from M-I SWACO; N-DRIL™ HT PLUS, and AD APT A™, marketed by Halliburton Energy Services, Inc. Tire fluid loss additive can also be present in a concentration in the range of about 0.5 to about 10 ppb of the drilling mud composition.

[0108] The drilling mud compositions can further include an ester additive. The ester additive can be present in a concentration in the range of about lwt. % to 20 wt. %.

[0109] The drilling mud compositions may also optionally include one or more metal salts, MX’_y, where M is a Group 1 or Group 2 metal, X' is a halogen, and y is 1 to 2, Exemplary metal salts include, NaCl, KC1, CaCk, MgCk, and the like. The total amount of such salts in the drilling mud compositions may range between about 10 wt. % to about 35 wt. % in the water phase. Organic additives that lower the water activity may also be used. [0110] W ater may also be present in oil-based drilling mud compositions at any convenient concentration, typically at a relatively low concentration, such as about 0 5 to about 20 wt %, about 0.5 to about 15 wt. %, about 0.5 to about 12.5 wt. %, about 0.5 to about 10 wt. %, about 0.5 to about 7.5 wt. %, about 0.5 to about 5 wt. %, about 0.5 to about 2.5 wt. %, about 0.5 to about 1 wt. %, about 1 to about 10 wt. %, about 1 to about 7.5 wt. %, about 1 to about 5 wt. %, about 1 to about 2,5 wt. %, about 2 5 to about 10 wt. %, about 2 5 to about 7 5 wt. %, about 2,5 to about 5 wt. %, about 5 to about 10 wt. %, or about 5 to about 7.5 wt. %.

[0111] The drilling mud compositions can further include wetting agents. In some embodiments, the wetting agents can be selected from the group consisting of tall oil-based fatty acid derivatives such as amides, amines, amidoammes, and imidazolines made by reactions of fatly acids and various ethanolamme compounds, vegetable oil-based derivatives, and combinations thereof. Commercially available examples of suitable wetting agents include, but are not limited to, DRILLTREAT™, QMC™, marketed by Halliburton Energy Services, Inc,, VERSAWET™, marketed by MI-SWACO. According to some embodiments, the wetting agent is present in at least a sufficient concentration such that the drilling mud composition maintains a stable emulsion or an invert emulsion. According to some embodiments, the wetting agent may be present in a concentration of at least 0.25 ppb of the drilling mud composition. The wetting agent can also be present m a concentration in the range of about 0.05 ppb to about 20 ppb, such as about 0.25 ppb to about 20 ppb of the drilling mud composition. In other embodiments, the drilling mud compositions may lack a wetting agent.

[0112] Any of the drilling mud compositions described hereinabove may be formulated m a variety of ways. Formulation may take place prior to introducing the drilling mud composition into a wellbore and/or within a wellbore itself. In certain embodiments, formulation of the drilling mud compositions may occur during a drilling operation.

[0113] According to various embodiments, methods for forming a drilling mud composition may comprise providing at least one base drilling mud, and combining a pluralit' of particles comprising at least transitional friction reducti on polymer particl es with the at least one base drilling mud to produce a drilling mud composition with a coefficient of friction less than that of the at least one base drilling mud. At least a portion of the transitional friction reduction polymer particles are substantially dispersed in solid form in the at least one base drilling mud. The drilling mud composition may comprise about 0.1 wt. % to about 20 wt. % transitional friction reduction polymer particles, and at least about 50 mass percent of the transitional friction reduction polymer particles remain dispersed in solid form under bulk conditions of a drilling operation.

[0114] The transitional friction reduction polymer particles may be combined with the at least one base drilling mud before or during the course of drilling a wellbore using the drilling mud composition. In some embodiments, combining the plurality of particles with the at least one base drilling mud may comprise introducing the plurality of particles into the at least one base drilling mud within a wellbore. In such embodiments, a drilling operation may begin with a drilling mud composition lacking the transitional friction reduction polymer particles, since frictional losses may be negligible early on during the drilling process (e.g., when the wellbore is shorter). After frictional losses become more significant, the plurality of particles may be introduced into the wellbore, where they may undergo mixing wath the at least one base drilling mud to form a drilling mud composition of the present disclosure. The plurality of particles may be introduced into the wellbore neat, or admixed with a suitable carrier fluid, such as a portion of the at least one base drilling mud or a base oil.

[0115] In some or other embodiments, the plurality of particl es, specifically the transitional friction reduction polymer particles, may be blended with a quantity of the at least one base drilling mud (e.g., to form a concentrate), which may then be introduced into a wellbore to modify a larger quantity of base drilling mud therein. Specifically, according to some embodiments, combining the plurality⁷ of particles with the at least one base drilling mud may comprise blending the plurality of particles with a first portion of the at least one base drilling mud to form a first drilling mud composition, and introducing the first drilling mud composition into a second portion of the at least one base dril ling mud within the wellbore.

[ 0116] In some or other embodiments, the plurality of particles, specifically the transitional friction reduction polymer particles, may be blended with a quantity of drilling mud composition to form a concentrate of the transitional friction reduction polymer particles. Suitable blending techniques may include, for example, mixing, stirring, homogenization, and the like. The concentrate may then be blended with at least one base drilling mud, either within a wellbore or outside a wellbore, to form a drilling mud composition having a final concentration of the transitional friction reduction polymer particles.

[0117] According to various embodiments, the transitional friction reduction polymer particles may be present in a drilling mud composition of the present disclosure in an amount ranging between about 0.1 wl % to about 20 wt. %, about 1 wf. % to about 15 wt. %, or about 5 wl % to about 10 wt. %. All weight percentages are based on the total weight of the drilling mud composition. Amounts of the transitional friction reduction polymer particles above 20 wt. % or below 0.1 wt. % are also contemplated by the present disclosure. [0118] Drilling mud compositions of the present disclosure have a coefficient of friction less than that of the at least one base drilling mud composition. Some drilling mud compositions may have a coefficient of friction of about 0.40 or less, about 0.30 or less, about 0.25 or less, about 0.20 or less, about 0.15 or less, about 0.10 or less, or about 0.05 or less. Additionally or alternati vely, the coefficient of friction may be about 0.01 or more, about 0.03 or more, about 0.05 or more, about 0.10 or more, about 0.20 or more, about 0 25 or more, or about 0 30 or more. Ranges of the coeffi cient of friction of the drilling mud compositions may include ranges of about 0.01 to about 0.40, about 0.05 to about 0.30, about 0.10 to about 0.25, or about 0 15 to about 0.20.

[0119] Additionally or alternatively, the drilling mud compositions of the present disclosure may be characterized by a change in the coefficient of friction relative to the coefficient of friction of the at least one base mud without the transitional friction reduction polymer particles being present. In other words, the drilling mud compositions of the present disclosure may have a coefficient of friction that is about 5% or more less than, about 10% or more less than, about 15% or more less than, about 20% or more less than, about 25% or more less than, or about 30% or more less than, about 35% or more less than, about 40% or more less than, about 45% or more less than, about 50% or more less than, about 55% or more less than, or about 60% or more less than the coefficient of friction of the at least one base drilling mud in the absence of the transitional friction reduction polymer particles. Ranges over which the coefficient of friction may be reduced relative to the base drilling mud without the transitional friction reduction polymer particles being present include ranges of about 5% to about 60% lower, about 10% to about 50% lower, about 15% to about 40% lower, about 20% to about 35% lower, or about 25% to about 30% lower.

[0120] The drilling mud compositions, including the transitional friction reduction polymer particles therein, may be used in various drilling operations or in any other downhole operation in which reduced friction may be desirable. In addition to drilling operations, the compositions disclosed herein may also he used in completion operations. The drilling mud compositions of the present disclosure may be particularly useful in drilling operations having operational and/or mechanical constraints, such as m Extended Reach drilling operations. For example, certain drilling operations may be constrained due to torque limits at the drilling rig. The torque constraints may be due to maximum torque that a driver can deliver and/or the maximum torque that the drilling s tring can withstand before metal failure occurs. Such constraints are therefore different for different drilling rigs due to either the size of the driver and/or the drill string in use, as well as the actual conditions present in the wellbore. The term‘Operating Torque” refers to the acceptable upper limit of torque in a drilling operation, taking into account a safety margin under the torque limit. The torque limit represents the torque value at which failure may occur. The Operating Torque can be measured by a dedicated device (e.g. , a torque sub) and/or by measured power usage of the driver. Drilling operations may be conducted with at least a 10% safety margin between the Operating Torque and the torque limit. When the Operating Torque is nearing or exceeding what is considered to be a reasonable safety margin, the length of the wellbore may be limited until corrective action can be taken to alleviate the excess torque. Operating changes that can be performed to reduce the Operating Torque include, for example, reducing the rate of penetration (the forward rate of drilling), removing accumulated cuttings from the wellbore, removing the drill siring from the wellbore and replacing/refurbishing worn components, and/or reducing the amount of low gravity solids (ground down cuttings) from the circulating drilling mud composition. These steps to reduce the Operating Torque can be expensive and time consuming, and may offer little benefit. Therefore, the addition of transitional friction reduction polymer particles to a drilling mud, as described herein, may be beneficial to reduce the Operating Torque facilitate a drilling operation, such as to increase rate of penetration and/or allow for a wellbore of greater length to be drilled.

[0121] The drilling mud compositions described herein may be formulated prior to or during the course of conducting a drilling operation, as referenced in brief above. In some embodiments, the drilling mud compositions of the present disclosure may be formulated by combining at least one base drilling mud, transitional friction reduction polymer particles, and any optional additives outside the wellbore, and the drilling mud composition may be introduced into the wellbore in a completely formulated or near-completely formulated state.

[0122] In other embodiments, the transitional friction reduction polymer particles may be combined with a base drilling mud within the wellbore. Optional additives may be introduced to the base drilling mud m combination with the transitional friction reduction polymer particles, or separately from the transitional friction reduction polymer particles, either before or after combining the transitional friction reduction polymer particles with the base drilling mud. According to some embodiments, any optional additives may already be present in the at least one base drilling mud before the transitional friction reduction polymer particles are combined therewith

[0123] According to some embodiments, the transitional friction reduction polymer particles may be introduced neat into the at least one base drilling mud within the wellbore. In other embodiments, the transitional friction reduction polymer particles may be introduced in fluid form into the at least one base drilling mud within the wellbore. In more specific embodiments, the transitional friction reduction polymer particles may be combined with a first portion of the at least one base drilling mud to form a first drilling mud composition (e.g., a concentrate comprising transitional friction reduction polymer particles), and the first drilling mud composition may be introduced into a second portion of the at least one base drilling mud within the wellbore to complete the formulation of the drilling mud composition. Optionally, the first drilling mud composition may be formulated at an off-site location and be transferred to a wellbore for introduction thereto.

[0124] Methods of the present disclosure may further comprise extending the wellbore by- drilling in the presence of the plurality of particles, specifically the transitional friction reduction polymer particles. Benefits of extending the wellbore in the presence of the transitional friction reduction polymer particles may include, for example, decreasing friction during rotation of the drill string and/or reducing Operating Torque. The drilling mud compositions of the present disclosure may be used from the outset of a drilling operation, or they may be used in a drilling operation m response to reaching operational and/or mechanical limits, such as Operating Torque or torque limits. That is, in some embodiments, an unmodified drilling mud composition may be used to conduct a first part of the drilling operation, and a drilling mud composition of the present disclosure may be used to conduct a second portion of the drilling operation.

[0125] Accordingly, methods of the present disclosure may comprise providing at least one drilling mud composition to a drilling operation, and extending a wellbore by drilling in the presence of the at least one drilling mud composition. The at least one drilling mud composition comprises a plurality of particles comprising at least transitional friction reduction polymer particles, and at least about 50 mass percent of the transitional friction reduction polymer particles remain substantially dispersed in solid form in the at least one drilling mud composition under bulk conditions of the drilling operation. Ty pical bulk conditions that may be encountered during a drilling operation are specified above.

[0126] According to some embodiments, drilling methods of the present disclosure may further comprise drilling a first portion of the wellbore with at least one base drilling mud lacking the transitional friction reduction polymer particles. In still further embodiments, the drilling methods may further comprise drilling a second portion of the wellbore in the presence of at least one drilling mud composition comprising the transitional friction reduction polymer particles.

[0127] In more specific embodiments, drilling methods of the present disclosure may comprise combining the plurality of particles with the at least one base drilling mud within the first portion of the wellbore or within a second portion of the wellbore, and extending the wellbore by drilling the second portion of the wellbore m the presence of the at least one drilling mud composition comprising the transitional friction reduction polymer particles. In some or other more specific embodiments, drilling methods of the present disclosure may comprise combining the plurality of particles with a first portion of the at least one base drilling mud to form a first drilling mud composition, introducing the first drilling mud composition into a second portion of the at least one base drilling mud within the first portion of the wellbore or within a second portion of the wellbore to form the at least one drilling mud composition, and extending the wellbore by drilling the second portion of the wellbore in the presence of the at least one drilling mud composition.

[0128] In some or other embodiments, drilling methods of the present disclosure disclosure may comprise introducing a base drilling mud into a wellbore, conducting a drilling operation for a period of time with the base drilling mud composition, and subsequently introducing the transitional friction reduction polymer particles into the wellbore. The transitional friction reduction polymer particles may be introduced in a portion of the base drillin mud composition, according to some embodiments. The methods may comprise determining a torque limit for the drilling operation, and optionally setting the Operating Torque. In some embodiments, the transitional friction reduction polymer particles may be introduced into the wellbore when the Operating Torque of the drillin operation is about 90% of the torque limit or greater, about 95% of the torque limit or greater, or about 99% of the torque limit or greater.

[0129] According to some embodiments, introducing transitional friction reduction polymer particles into a drilling operation may comprise blending the transitional friction reduction polymer particles and at least one base drilling mud to form a first drilling mud composition, and introducing the first drilling mud composition into a wellbore. Introducing the first drilling mud composition into the wellbore can comprise pumping the first drilling mud composition into the wellbore. The pumping may be performed continuously (i.e., providing a constant or variable flow' of the first drilling mud composition at all times), periodically, or intermittently (i.e. , alternating between periods of flow and no flow of the first drilling mud composition). Particular methods may further include continuously, periodically, or intermittently providin a second amount of transitional friction reduction polymer particles to the first drilling mud composition already provided to the well (e.g., to replace adsorptive or degradative loss of the transitional friction reduction polymer particles). In some methods, continuous provision of the transitional friction reduction polymer particles or a first drilling mud composition formed therefrom may provide an overall reduction in the amount of transitional friction reduction polymer particles used during the drilling operation. Alternatively, continuous provision of the transitional friction reduction polymer particles or a first drilling mud composition formed therefrom may allow smoother drilling to take place during the drilling operation. The wellbore can be, without limitation, an oil, gas, or water production well, or an injection well. In some embodiments, the wellbore penetrates a reservoir or is located adjacent to a reservoir.

[0130] The drilling operations can include any number of additional optional steps. In some embodiments, the drilling operations can further include the step of removing at least a portion of the at least one drilling mud composition from the wellbore after introduction thereof. Some drilling operations may include one or more of the following optional steps: mounting and cementing of well pipes; mounting a blowout preventer or lubricator in the top of the well; drilling, at a distance from the well, a second well against a section of a first well to the effect that the second well achieves operational contact with the first well; mounting and cementing of well pipes in the second well; mounting a blowout preventer or lubricator in the top of the second well; whereafter the drilling from one of the first or second well continues down into the reservoir and the other well which is not drilled to the reservoir is filled wholly or partially with a fluid and a drilling tool is placed in the other well and the other well is subsequently closed so that the other well can be accessed at a later point in time, and that the tool is left in the other well so that this tool can establish a connection to the one of the first or second wells into which the drilling continued.

[0131] Still other optional steps in a drilling operation may include one or more of the following: calculating a desired path for a well of interest relative to a reference well; measuring a position of the well of interest relative to the reference well at a location along the wellbore; calculating an actual path of the w-ell of interest based at least in part on the measured position of the well of interest relative to the at least one reference well; comparing the actual path of the at least one well of interest to the desired path of the well of interest; and adjusting a drilling system to modify the actual path of the well of interest based at least in part on a deviation between the actual path of the well of interest and the desired path of the w-ell of interest.

[0132] Methods of the present disclosure may further include one or more steps of advancing a downhole tool in the wellbore. Suitable wellbore tools are not considered to be particularly limited and will be familiar to one having ordinary skill in the art

[0133] Drilling operations may take place in the presence of one or more particle screens, which may aid in removing drill cutings above a threshold size from the drilling mud. The one or more particle screens may have an effective screening size that is selected based upon the average particle size of the drill cuttings that are generated. Therefore, according to various embodiments, drilling methods of the present disclosure may take place in the presence of one or more particle screens having an effective screening size, where the effective screening size determines the maximum size of particles that may pass through apertures in the screen and remain circulating in the wellbore. According to various embodiments, the drilling operations of the present disclosure may he conducted with one or more particle screens having an effective screening size of about 500 micrometer (microns) or more, or about 300 microns or more, or about 250 microns or more, or about 200 microns or more, or about 150 microns or more, or about 100 microns or more, or about 50 microns or more. As such, particles that are these sizes or larger may be removed from the drilling mud compositions.

[0134] In addition to drill cuttings, transitional friction reduction polymer particles and other particulate materials larger tha the effective screening size may be excluded (removed) by the one or more particle screens. According to various embodiments of the present disclosure, the transitional friction reduction polymer particles may have a particle size below the effective screening size of the one or more particle screens. By selecting the particle size of the transitional friction reduction polymer particles in this manner, unwanted exclusion of the transitional friction reduction polymer particles upon the particle screens may be avoided.

[0135] In some or other embodiments, the transitional friction reduction polymer particles may be smaller m size than the cutting particles (drill cuttings) generated by the drilling operation. Surprisingly, the transitional friction reduction polymer particles of the present disclosure may provide beneficial friction reduction effects, even when they are smaller in size than other particulate materials in the wellbore. According to various embodiments of the present disclosure, at least about 50% of the transitional friction reduction polymer particles may be smaller than the average size of the drill cuttings, or at least about 70% may be smaller than the average size of the drill cuttings, or at least about 90% may be smaller than the average size of the drill cuttings, or at least about 95% may be smaller than the average size of the drill cuttings. In particular embodiments, the transitional friction reduction polymer particles may have a Dso (median size for volume distribution; i.e. the Dso is the particle size for which fifty percent by volume of the particles has a size lower than the Dso) from about 10 pm to about 80 pm, between about 15 pm and about 70 pm, between about 20 pm and about 60 pm, between about 25 pm and about 50 pm, between about 30 pm and about 65 pm, or between about 40 pm and about 60 pm. The Dso may be measured using laser diffraction, for example using a Microtrac S3000 particle size analyzer as described further in the examples. In more specific embodiments, the transitional friction reduction polymer particles may range in size from about 10 to about 80 microns, between about 15 and about 70 microns, between about 20 and about 60 microns, between about 25 and about 50 microns, between about 30 and about 65 microns, or between about 40 and about 60 microns.

[0136] In some or other embodiments, methods of the present disclosure employ transitional friction reduction polymer particles to reduce the Operating Torque in a given drilling operation. According to some embodiments, the transitional friction reduction polymer particles may be employed to reduce the Operating Torque of the drilling operation when the Operating Torque has reached a threshold level, such as about 90% of the torque limit or greater, about 95% of the torque limit or greater, or about 99% of the torque limit or greater. The drilling mud compositions of the present disclosure may reduce the Operating Torque of the drilling operation by at least about 1%, by at least about 2%, by at least about 3%, by at least about 5%, or by at least about 10%. Accordingly, the drilling mud compositions of the present disclosure may allow the drilling operation to be conducted with an Operating Torque of about 99% or less, about 98% or less, about 97% or less, about 95% or less, or about 90% or less of the Operating Torque of the same drilling operation performed with a comparable drilling mud composition lacking the transitional friction reduction polymer particles, such as the base drilling mud.

[0137] The drilling mud compositions may be exposed to temperatures in the wellbore ranging from a low of about 50°C, 60°C, 70°C, 80°C, 90°C, 100°C, or 125°C to a high of about 170°C, and pressures ranging from ambient pressure to a high of about 100 bar (10,000 kPa), 200 bar (20,000 kPa), 300 bar (30,000 kPa), 400 bar (40,000 kPa), 500 bar (50,000 kPa), or 600 bar (60,000 kPa). The drilling mud compositions may be utilized when system components have a rotational speed of about 1000 rpm or less, about 800 rpm or less, about 700 rpm or less, and greater than about 0 rpm, such as a rotational speed from about 1 to about 1000 rpm. The drilling mud compositions may also be utilized with or without rotation of the drill string but instead with longitudinal motion of the drill string at a speed of 10,000 m/hr (meters per hour) or less, including 1,000 m/hr or less, 100 m/hr or less, or 10 m/hr or less.

[0138] Embodiments disclosed herein include:

[0139] A. Drilling mud compositions. The drilling mud compositions comprise: at least one base drilling mud; and a plurality of particles comprising at least (transitional) friction reduction polymer particles, the (transitional) friction reduction polymer particles being substantially dispersed in solid form in the at least one base drilling mud and at least about 50 mass percent of the (transitional) friction reduction polymer particles remaining dispersed m solid form under bulk conditions of a drilling operation

[0140] B. Drilling mud compositions. The drilling mud compositions comprise at least one base drilling mud; and a plurality of particles comprising friction reduction particles; said friction reduction particles comprising a polymer having a polymerized monomer unit with (i) at least one polar head group comprising a heteroatom and/or heteroatom functional group, said heteroatom being selected from the group consisting of N, O, S, and P; and (li) at least one oleophilic tail group which is a substituted or unsubstituted hydrocarbyl group; the friction reduction particles further being substantially dispersed in solid form in the at least one base drilling mud; wherein preferably at least 50 wt. % of the friction reduction polymer particles remain dispersed in solid form at temperatures below 170°C and pressures below 600 bar.

[0141] C. Methods for making a drilling mud composition. The methods comprise: providing at least one base drilling mud; and combining a plurality of particles comprising at least (transitional) friction reduction polymer particles with the at least one base drilling mud, such that at least a portion of the transitional friction reduction polymer particles are substantially dispersed in solid form in the at least one base drilling mud to produce drilling mud composition with a coefficient of friction less than that of the at least one base drilling mud; wherein the drilling mud composition comprises about 0.1 wt. % to about 20 wt. % (transitional) friction reduction polymer particles; and wherein at least about 50 mass percent of the (transitional) friction reduction polymer particles remain dispersed in solid form under bulk conditions of a drilling operation .

[0142] D. Drilling methods. The drilling methods comprise: providing at least one drilling mud composition to a drilling operation, the at least one drilling mud composition comprising a plurality of particles comprising at least (transitional) friction reduction polymer particles substantially dispersed therein; wherein at least about 50 mass percent of the (transitional) friction reduction polymer particles remain dispersed in solid form in the at least one drilling mud composition under bulk conditions of the drilling operation; and extending a wellbore by drilling in the presence of the at least one drilling mud composition.

[0143] Embodiments A-D may have one or more of the following additional elements m any combination.

[0144] Element 1 : wherein the at least one base drilling mud comprises an oil-based mud.

[0145] Element 2: wherein the at least one base drilling mud comprises a water-based mud. [0146] Element 3: wherein the drilling mud composition comprises about 0.1 wt. % to about 20 wt. % transitional friction reduction polymer particles, preferably from 1 wt. % to 15 wt. %.

[0147] Element 4: wherein the (transitional) friction reduction polymer particles comprise a polymer having a polymerized monomer unit with (a) at least one polar head group, said at least one polar head group preferably comprising a heteroatom and/or heteroatom functional group, said heteroatom being selected from the group consisting of N, O, S, and P; and (b) at least one oleophilic tail group, said at least one oleophilic tail group preferably being a substituted or unsubstituted hydrocarbyl group.

[0148] Element 5: wherein the (transitional) friction reduction polymer particles comprise a polymer having a polymerized monomer unit with a formula of

Xm— Ar— (R¹ )n

wherein Ar is a single or multi-ring aromatic or heteroaromatic moiety, each X is a polar head group, and each R¹ is an oleophilic tail group that is a branched or unbranched, saturated or unsaturated, cyclic or acyclic, substituted or unsubstituted hydrocarbyl group having 1 to about 50 carbon atoms; wherein n is an integer greater than or equal to 1; and wherein m is an integer greater than or equal to 0 when at least one R¹ is substituted with a heteroatom functional group and/or when Ar is a heteroaromatic moiety, and otherwise m is an integer greater than or equal to 1; wherein each X and each R¹ are the same or different when m or n is greater than 1.

[0149] Element 6; wherein each X as defined in Element 5 is independently selected from the group consisting of OH, Ni b. NO-.. SO-R ^'.. OR², NHR², N(R²)₂, CHQ, CO2H, CO2R², CO2NH2, CQ2NHR², (O -N( R’) -. SO2NH2, SO2NHR², SQ₂N(R²)2, NHSO2R², NRSQ2R² and SOR²; R² preferably being hydrogen or C3-50 hydrocarbyl.

[0150] Element 7: wherein R¹ is a Cs to C 40 hydrocarbyl group, a C10 to C30 hydrocarbyl group, a C15 to C25 hydrocarbyl group, or a Ci5 to C20 hydrocarbyl group.

[0151] Element 8: wherein the (transitional) friction reduction polymer particles comprise a polymer having at least one polymerized monomer unit that is a hydroxylated aromatic monomer bearing a hydrocarbyl group.

[0152] Element 9: wherein the drilling mud composition further comprises at least one liquid friction reduction additive.

[0153] Element 10: wherein the at least one liquid friction reduction additive of Element 9comprises a cashew nut shell liquid or a derivative thereof.

[0154] Element 11 : wherein the (transitional) friction reduction polymer particles have a D50 from 15 pm to 70 pm [0155] Element 12: wherein at least a portion of the (transitional) friction reduction polymer particles are configured to form a transient liquid upon becoming disposed in a high- friction location, the transient liquid re-solidifying once the transient liquid is no longer in the high-friction location.

[0156] Element 13: wherein combining the plurality of particles with the at least one base drilling mud comprises introducing the plurality of particles into the at least one base drilling mud within the wellbore.

[0157] Element 14: wherein combining the plurality of panicles with the at least one base drilling mud comprises blending the plurality of particles with a first portion of the at least base one drilling mud to form a first drilling mud composition, and introducing the first drilling mud composition into a second portion of the at least one base drilling mud within the wellbore.

[0158] Element 15: wherein the method further comprises extending the wellbore by drilling in the presence of the plurality of particles.

[0159] Element 16: wherein drilling takes place in the presence of one or more particle screens having an effective screening size, and at least a portion of the (transitional) friction reduction polymer particles have a particle size below the effective screening size of the one or more particle screens.

[0160] Element 17: wherein drilling generates a plurality of cutting particles, and at least a portion of the (transitional) friction reduction polymer particles are smaller than the plurality of cutting particles.

[0161] Element 18: wherein at least a portion of the (transitional) friction reduction polymer particles become disposed in a high-friction location and transition to a transient liquid in the high-friction location during drilling; wherein the transient liquid re-solidities once the transient liquid is no longer in the high-friction location.

[0162] Element 19: wherein the at least one base drilling mud or the drilling mud composition further comprises at least one liquid friction reduction additive.

[0163] Element 20: wherein the method further comprises drilling a first portion of the wellbore with at least one base drilling mud lacking the (transitional) friction reduction polymer particles.

[0164] Element 21: wherein the method further comprises combining the plurality of particles with the at least one base drilling mud within the first portion of the wellbore or within a second portion of the wellbore; wherein extending the wellbore by drilling comprises drilling the second portion of the wellbore in the presence of the at least one drilling mud composition. [0165] Element 22: wherein the method further comprises combining the plurality of particles with a first portion of the at least one base drilling mud to form a first drilling mud composition; and introducing the first drilling mud composition into a second portion of the at least one base drilling mud within the first portion of the wellbore or within a second portion of the wellbore; wherein extending the wellbore by drilling comprises drilling the second portion of the wellbore in the presence of the at least one drilling mud composition.

[0166] Element 23: wherein at least a portion of the (transitional) friction reduction polymer particles become disposed in a high-friction location and transition to a transient liquid in the high-friction location during the drilling operation; wherein the transient liquid re solidifies once the transient liquid is no longer in the high-friction location.

[0167] By way of non-limiting example, exemplary combinations applicable to A-C include: 1 or 2 and 3; 1 or 2 and 4; 1 or 2 and 5; 1 or 2 and 7; 1 or 2 and 8; 1 or 2 and 10; 1 or 2 and 11; 3-5; 3-6; 3 and 7; 3 and 8; 3, 8 and 9; 3 and 10; 3 and 1 1 ; 4-6; 5 and 6; 5 and 8; 5, 6 and 8; 5, 6, 8 and 9; 5 and 10; 5 and 11; 7 and 8; 7-9; 7 and 10; 7 and 11; 8 and 10; 8 and 11; and 10 and 11. Additional exemplary' combinations applicable to B include any of the above exemplary combinations in further combination with one or more of elements 12-14 or to C include any of the above exemplary combinations in further combination with element 19, or elements 19 and 20; 19 and 21, any of which may be optionally in further combination with element 22. Still additional exemplary combinations applicable to B include: 12 and 14; 13 and 14; 12, 14 and 13; 13-15; 12, 14 and 16; and 13, 14 and 16. Still additional exemplary' combinations applicable to C include: 15 and 16; 15 and 17; 16 and 17; 19 and 20; and 19 and 21, any of which may be optionally in further combination with element 22.

[0168] To facilitate a better understanding of the embodiments described herein, the following examples of various representative embodiments are given. In no way should the following examples be read to limit, or to define, the scope of the present disclosure.

[0169] Coefficient of Friction (CoF) was determined using a Falex Block-on-Ring machine. The block was made of SAE 01 tool steel and the ring was made of SAE 4620 carbon steel. The block had a length of 15.76 mm (0.620 in.) and a width of 6.35 mm (0.250 in.). The ring had an outer diameter of 35 mm (1.377 in.) and a width of 8.15 mm (0.321 m.). The block had a surface roughness, Ra, ranging from 0.10 pm to 0.20 pm. The ring had a surface roughness, R_a, ranging from 0.15 pm to 0.30 pm. A new block and ring pair was used for each test.

[0170] Each sample was prepared by combining 200 mlL of oil-based mud and 15 g of a solid friction reduction additive, as specified in Table 2 below. Mixing was conducted using a Hamilton Beach 936-2 mixer operated at 10,000 rpm until the sample was well mixed.

[0171] The base mud was an oil-base mud having the tradename VERSACLEAN™, available from MI-SWACO. The base drilling mud had an average particle size of 37 microns before introducing any additional particulate materials in the tests discussed herein. The particle size distribution of the base drilling mud ranged between approximately 0.1-200 microns.

[0172] Friction reduction particles were obtained from several suppliers. Solid alkylphenol polymers w¾re obtained from Palmer or Cardo!ite. Graphite particles were obtained from Asbury Carbons. ULTRALUBE II, available from Integrity Industries, Inc., was used as a conventional liquid friction reduction compound in some comparative examples. Details concerning particle size and chemical compositions of the friction reduction particles are provided in Table 2 below'.

[0173] Each sample was loaded into the testing cell of the EaJex Block-on-Ring machine that was pre-loaded with a new pair of block and ring at each test. The interface between the block and the ring was fully emerged in the drilling mud composition.

[0174] Each test commenced with an initial running-in period with a ring rotation speed of 400 rpm, during which the load of the block applied to the ring was gradually increased from 0 to 5 Ibf and then from 5 to 15 Ibf while the system was warmed from ambient temperature to 75°C. A series of three ramping cycles were then performed consisting of a ramping-down step followed by a ramping-up step. During each ramping-dow^rn step, the ring rotation speed was decreased from 400 to 0 rpm at 1 rpm/s, and during each ramping-up step the ring rotation speed was increased from 0 rpm to 400 rpm at 1 rpm/s. During some of these transitions, the rotation of the ring was stopped for 2 minutes to allow system relaxation. COF vs. rpm relationships obtained during the ramping-up steps were quantitatively similar to that obtained during the ramping-down steps. The COF vs. rpm relationships obtained during the three ramping-down steps were averaged to obtain the reported COF vs. rpm relationship. In some instances, a given friction-reducing composition was tested multiple times, in which case the average value is reported. The testing protocol schematically shown in the Figure.

[0175] Particle size distribution (PSD) experiments were conducted on a Microtrac S3000 laser diffraction particle size analyzer equipped with a Microtrac automated small-volume recirculator (ASVR). Methanol was used as the solvent. During each test, a small amount of solid FRA or mud was added to the system. The solid recirculates with methanol through the measurement cell so that multiple PSD measurements can be made. The PSD converges as the solids de-agglomerate. The modes, or the maximum values of the converged PSDs, are specified as the particle sizes herein.

Table 2

³ product of MI-SWACO

product of Integrity Industries, Inc.

3basic brown alkyl phenol CNSL polymer particle available from Palmer, Inc.

intermediate black furfural-CNSL copolymer available from Palmer, Inc.

’basic black furfural-CNSL copolymer available from Palmer, Inc.

⁶high temperature resistant furfural-CNSL copolymer available from Palmer, Inc.

^"brown, granular cured solid resin derived from CNSL available from Cardolite, Inc.

8black, granular cured solid resin derived from CNSL available from Cardolite, Inc.

^product of Asbury, Inc.

[0176] As shown, the polymeric friction reduction particles were all effective at decreasing friction. Even when the friction reducer particle size was smaller than the average particle size of the base drilling mud, friction reduction was still realized (Sample 4). In contrast, samples C3 and C4 did not show friction reduction for graphite particles when the friction reducer particle size was below the average particle size of the base drilling mud. In general, the solid friction reduction particles provided greater friction reduction than a liquid friction reducer control.

[0177] All documents described herein are incorporated by reference herein for purposes of all jurisdictions where such practice is allowed, including any priority documents and/or testing procedures to the extent they are not inconsistent with this text. As is apparent from the foregoing general description and the specific embodiments, while forms of the disclosure have been illustrated and described, various modifications can be made without departing from the spirit and scope of the disclosure. Accordingly, it is not intended that the disclosure be limited thereby. For example, the compositions described herein may be free of any component, or composition not expressly recited or disclosed herein. Any method may lack any step not recited or disclosed herein. Likewise, the term“comprising” is considered synonymous with the term“including.” Whenever a method, composition, element or group of elements is preceded with the transitional phrase“comprising,” it is understood that we also contemplate the same composition or group of elements with transitional phrases“consisting essentially of,”“consisting of,”“selected from the group of consisting of,” or‘is” preceding the recitation of the composition, element, or elements and vice versa.

[0178] Unless otherwise indicated, all numbers expressing quantities of ingredients, properties such as molecular weight, reaction conditions, and so forth used the present specification and associated claims are to be understood as being modified in all instances by the term“about.” Accordingly, unless indicated to the contrary, the numerical parameters set forth in the following specification and attached claims are approximations that may vary depending upon the desired properties sought to be obtained by the embodiments of the present invention. At the very' least, and not as an attempt to limit the application of the doctrine of equivalents to the scope of the claim, each numerical parameter should at least be construed in light of the number of reported significant digits and by applying ordinary' rounding techniques.

[0179] Whenever a numerical range with a lower limit and an upper limit is disclosed, any number and any included range failing within the range is specifically disclosed. In particular, every' range of values (of the form,“from about a to about b,” or, equivalently,“from approximately a to b,” or, equivalently,“from approximately a-b”) disclosed herein is to be understood to set forth every number and range encompassed within the broader range of values. Also, the terms in the claims have their plain, ordinary' meaning unless otherwise explicitly and clearly defined by the patentee. Moreover, the indefinite articles“a” or“an,” as used in the claims, are defined herein to mean one or more than one of the element that it introduces.

[0180] One or more illustrative embodiments are presented herein. Mot ail features of a physical implementation are described or shown in this application for the sake of clarity. It is understood that in the development of a physical embodiment of the present disclosure, numerous implementation-specific decisions must be made to achieve the developer's goals, such as compliance with system-related, business-related, government-related and other constraints, which vary' by implementation and from time to time. While a developer's efforts might be time-consuming, such efforts would be, nevertheless, a routine undertaking for one of ordinary' skill in the art and having benefit of this disclosure.

[0181] Therefore, the present disclosure is well adapted to attain the ends and advantages mentioned as well as those that are inherent therein. The particular embodiments disclosed above are illustrative only, as the present disclosure may be modified and practiced in different but equivalent manners apparent to one having ordinary skill m the art and having the benefit of the teachings herein. Furthermore, no limitations are intended to the details of construction or design herein shown, other than as described in the claims below it is therefore evident that the particular illustrative embodiments disclosed above may be altered, combined, or modified and all such variations are considered within the scope and spirit of the present disclosure. The embodiments illustratively disclosed herein suitably may be practiced in the absence of any element that is not specifically disclosed herein and/or any optional element disclosed herein.

Claims

What is claimed is:

1. A drilling mud composition comprising:

at least one base drilling mud; and

a plurality of particles comprising at least transitional friction reduction polymer particles, the transitional friction reduction polymer particles being substantially dispersed in solid form in the at least one base drilling mud and at least about 50 mass percent of the transitional friction reduction polymer particles remaining dispersed in solid form under bulk conditions of a drilling operation.

2. The drilling mud composition of claim 1 , wherein the at least one base drilling mud comprises an oil-based mud.

3. The drilling mud composition of claim 1, wherein the at least one base drilling mud comprises a water-based mud.

4. The drilling mud composition of any one of claims 1-3, wherein the drilling mud composition comprises about 0.1 wt. % to about 20 wt. % transitional friction reduction polymer particles.

5. The drilling mud composition of any one of claims 1-4, wherein the transitional

friction reduction polymer particles comprise a polymer having a polymerized monomer unit with at least one polar head group and at least one oleophilic tail group.

6. The drilling mud composition of any one of claims 1 to 5, wherein the transitional friction reduction polymer particles comprise a polymer having a polymerized monomer unit with a formula of

Xnr-Ar-(R^fj„ wherein Ar is a single or multi-ring aromatic or heteroaromatic moiety , each X is a polar head group, and each R³ is an oleophilic tail group that is a branched or unbranched, saturated or unsaturated, cyclic or acyclic, substituted or unsubstituted hydrocarby! group having 1 to about 50 carbon atoms;

wherein n is an integer greater than or equal to 1; and

wherein m is an integer greater than or equal to 0 when at least one R³ is substituted with a heteroatom functional group and/or when Ar is a heteroaromatic moiety, and otherwise m is an integer greater than or equal to 1 ;

wherein each X and each R¹ are the same or different when m or n is greater than 1 7. The drilling mud composition of claim 6, wherein each X is independently selected from the group consisting of OH, NH₂, NOr, SO2R², OR², NHR², N(R²)₂, CHO, CO2H, CQ2R², CO2NH2, CO2NHR², CQ₂N(R²)₂, SO2NH2, SQ2NHR², SQ₂N(R²)₂, NHSO2R², NRSO2R² and SOR²; wherein R² is hydrogen or Ci-so hydrocarbyl. 8. The drilling mud composition of any one of claims 1-7, wherein the transitional friction reduction polymer particles comprise a polymer having at least one polymerized monomer unit that is a hydroxylated aromatic monomer hearing a hydrocarbyl group. 9. The drilling mud composition of any one of claims 1-8, further comprising:

at least one liquid friction reduction additive.

10. The drilling mud composition of claim 9, wherein the at least one liquid friction reduction additive comprises a cashew nut shell liquid or a derivative thereof.

11. The drilling mud composition of any one of claims 1-10, wherein the transitional friction reduction polymer particles range between about 15 microns to about 70 microns in size. 12. The drilling mud composition of any one of claims 1-11, wherein at least a portion of the transitional friction reduction polymer particles are configured to form a transient liquid upon becoming disposed in a high-friction location, the transient liquid re solidifying once the transient liquid is no longer in the high-friction location. 13. A method comprising:

providing at least one base drilling mud; and

combining a plurality of particles comprising at least transitional friction reduction polymer particles with the at least one base drilling mud, such that at least a portion of the transitional friction reduction polymer particles are substantially dispersed in solid form in the at least one base drilling mud to produce drilling mud composition with a coefficient of friction less than that of the at least one base drilling mud;

wherein the drilling mud composition comprises about 0.1 wt. % to about 20 wt. % transitional friction reduction polymer particles; and

wherein at least about 50 mass percent of the transitional friction reduction polymer particles remain dispersed in solid form under bulk conditions of a drilling operation.

14 The method of claim 13, wherein the transitional friction reduction polymer particles comprise a polymer having a polymerized monomer unit with at least one polar head group and at least one oleophilic tail group

15 The method of claim 14, wherein the transitional friction reduction polymer particles comprise a polymer having a polymerized monomer unit with a formula of

Xm-Ar-iR¹) wherein Ar is a single or multi-ring aromatic or heteroaromatic moiety, each X is a polar head group, and each R¹ is an oleophilic tail group that is a branched or unbranched, saturated or unsaturated, cyclic or acyclic, substituted or unsubstituted hydrocarbyl group having 1 to about 50 carbon atoms;

wherein n is an integer greater than or equal to 1 ; and

wherein m is an integer greater than or equal to 0 when at least one R1 is substituted with a heteroatom functional group and/or when Ar is a heteroaromatic moiety, and otherwise m is an integer greater than or equal to 1;

wherein each X and each R¹ are the same or different when m or n is greater than 1.

16 The method of claim any one of claims 13-15, wherein each X is independently

selected from the group consisting of OH, NH₂, NO:?, SO2R², OR, NHR², NH(R²)₂, CHO, CO2H, CO2R², CO2NH2, CO2.NHR², CO’N{ R³ SO2NH2, SO2NHR², S0₂N(R²)2, NHSO2R², NRSO2R² and SOR²; wherein R² is hydrogen or C1-50 hydrocarbyl.

17. The method of any one of claims 13-16, wherein the transitional friction reduction polymer particles comprise a polymer having at least one polymerized monomer unit that is a hydroxy!ated aromatic monomer bearing a hydrocarby! group. 18. The method of any one of claims 13-17, wherein combining the plurality of particles with the at least one base drilling mud comprises introducing the plurality of particles into the at least one base drilling mud within the wellbore.

19 The method of any one of claims 13-17, wherein combining the plurality of particles with the at least one base drilling mud comprises blending the plurality of particles with a first portion of the at least base one drilling mud to form a first drilling mud composition, and introducing the first drilling mud composition into a second portion of the at least one base drilling mud wi thin the wellbore. 20. The method of claim 18 or claim 19, further comprising:

extending the wellbore by drilling in the presence of the plurality of particles.

1 The method of claim 20, wherein drilling takes place in the presence of one or more particle screens having an effecti ve screening size, and at least a portion of the transitional friction reduction polymer particles have a particle size below' the effective screening size of the one or more particle screens.

The method of claim 20, wherein drilling generates a plurality of cutting particles, and at least a portion of the transitional friction reduction polymer particles are smaller than the plurality of cutting particles.

23. The method of any one of claims 20-22, wherein at least a portion of the transitional friction reduction polymer particles become disposed in a high-friction location and transition to a transient liquid in the high-friction location during drilling;

wherein the transient liquid re-solidifies once the transient liquid is no longer in the high-friction location.

14 The method of any one of claims 13-23, wherein the at least one base drilling mud or the drilling mud composition further comprises at least one liquid friction reduction additive.

25. The method of claim 24, wherein the at least one liquid friction reduction additive comprises a cashew nut shell liquid or a derivative thereof.

26. The method of any one of claims 13-25, wherein the at least one base drilling mud comprises an oil-based mud.

27. The method of any one of claims 13-25, wherein the at least one base drilling mud comprises a water-based mud.

28. A method comprising:

providing at least one drilling mud composition to a drilling operation, the at least one drilling mud composition comprising a plurality of particles comprising at least transitional friction reduction polymer particles substantially dispersed therein;

wherein at least about 50 mass percent of the transiti onal fricti on reduction polymer particles remain dispersed in solid form in the at least one drilling mud composition under bulk conditions of the drilling operation; and

extending a wellbore by drilling in the presence of the at least one drilling mud composition.

29. The method of claim 28, further comprising:

drilling a first portion of the wellbore with at least one base drilling mud lacking the transitional friction reduction polymer particles. 30. The method of claim 29, further comprising:

combining the plurality of particles with the at least one base drilling mud within the first portion of the wellbore or within a second portion of the wellbore;

wherein extending the wellbore by drilling comprises drilling the second portion of the wellbore in the presence of the at least one drilling mud composition.

31 The method of claim 29, further comprising:

combining the plurality of particles with a first portion of the at least one base drilling mud to form a first drilling mud composition; and

introducing the first drilling mud composition into a second portion of the at least one base drilling mud within the first portion of the wellbore or within a second portion of the wellbore:

32. The method of any one of claims 28-31, wherein the transitional friction reduction polymer particles comprise a polymer having a polymerized monomer unit with at least one polar head group and at least one oleophilic tail group.

33. The method of claim 32, wherein the transitional friction reduction polymer particles comprise a polymer having a polymerized monomer unit with a formula of

X,» Ar ί R^! i , wherein Ar is a single or multi-ring aromatic or heteroaromatic moiety', each X is a polar head group, and each R¹ is an oleophilic tail group that is a branched or unbranched, saturated or unsaturated, cyclic or acyclic, substituted or unsubstituted hydrocarbyl group having 1 to about 50 carbon atoms;

wherein n is an integer greater than or equal to 1; and

wherein m is an integer greater than or equal to 0 when at least one R^f is substituted with a functional group and/or when Ar is a heteroaromatic moiety, and otherwise m is an integer greater than or equal to 1;

wherein each X and each R^’! are the same or different when m or n is greater than 1.

34. The method of claim 33, wherein each X is independently selected from the group consisting

CO2NH2,

NRSO2R² and SQR²; wherein R² is hydrogen or C i-50 hydrocarbyl.

35. The method of any one of claims 28-34, wherein the transitional friction reduction polymer particles comprise a polymer having at least one polymerized monomer unit that is a hydroxyiated aromatic monomer bearing a hydrocarbyl group.

36. The method of any one of claims 28-35, wherein the at least one drilling mud

composition comprises about 0.1 wt. % to about 20 wt. % transitional friction reduction polymer particles.

37. The method of any one of claims 28-36, wherein the at least one drilling mud

composition further comprises at least one liquid friction reduction additive. 38. The method of claim 37, wherein the at least one liquid friction reduction additive comprises a cashew nut shell liquid or a derivative thereof.

39. The method of any one of claims 28-38, wherein drilling takes place in the presence of one or more particle screens having an effective screening size, and at least a portion of the transitional friction reduction polymer particles have a particle size below the effective screening size of the one or more particle screens.

40. The method of any one of claims 28-39, wherein drilling generates a plurality of cutting particles, and at least a portion of the transitional friction reduction polymer particles are smaller than the plurality of cutting particles.

41. The method of any one of claims 28-40, wherein the at least one base drilling mud comprises an oil-based mud.

42. The method of any one of claims 28-40, wherein the at least one base drilling mud comprises a water-based mud. 43. The method of any one of claims 28-42, wherein at least a portion of the transitional friction reduction polymer particles become disposed in a high- friction location and transition to a transient liquid in the high-friction location during the drilling operation;