WO2010144398A2

WO2010144398A2 - Method for treating hydrocarbon-bearing formations with polyfluoropolyether silanes

Info

Publication number: WO2010144398A2
Application number: PCT/US2010/037705
Authority: WO
Inventors: Rudolf J. Dams; Steven J. Martin; Yong K. Wu
Original assignee: 3M Innovative Properties Company
Priority date: 2009-06-10
Filing date: 2010-06-08
Publication date: 2010-12-16
Also published as: WO2010144398A3

Abstract

Method comprising contacting a hydrocarbon-bearing formation with a treatment composition comprising solvent and a fluoropolyether silane. The fluoropolyether silane: is selected from the group consisting of: (a) Rf'-[Q-X'-(Si(Y')_w(Y)_3-W)_m]_n; (b) a compound comprising at least one first divalent unit represented by formula (I): and at least one of (i) a second divalent unit comprising a pendent -Si(Y')_w(Y)_3-w group; or (ii) a monovalent unit comprising a thioether linkage and at least one terminal -Si(Y')_w(Y)_3-w group; and (c) combinations thereof. Hydrocarbon-bearing formations treated according to this method are also disclosed.

Description

METHOD FOR TREATING HYDROCARBON-BEARING FORMATIONS WITH

POLYFLUOROPOLYETHER SILANES

Cross Reference to Related Applications This application claims the benefit of U. S. Provisional Application No.

61/185,639, filed June 10, 2009, the disclosure of which is incorporated by reference herein in its entirety.

Background Fluorochemical compounds are commercially useful, for example, for surface- energy modification and may provide desirable macroscopic properties (e.g., soil repellency and soil release).

In the oil and gas industry, some hydrocarbon and fluorochemical compounds have been used to modify the wettability of reservoir rock, which may be useful, for example, to prevent or remedy water blocking (e.g., in oil or gas wells) or liquid hydrocarbon accumulation (e.g., in gas wells) in the vicinity of the wellbore (i.e., the near wellbore region). Water blocking and liquid hydrocarbon accumulation may result from natural phenomena (e.g., water-bearing geological zones or condensate banking) and/or operations conducted on the well (e.g., using aqueous or hydrocarbon fluids). Water blocking and condensate banking in the near wellbore region of a hydrocarbon-bearing geological formation can inhibit or stop production of hydrocarbons from the well and hence are typically not desirable. Not all hydrocarbon and fluorochemical compounds, however, provide the desired wettability modification. And some of these compounds modify the wettability of siliciclastic hydrocarbon-bearing formations but not carbonate formations, or vice versa. Hence, there is a continuing need for alternative and/or improved techniques for increasing the productivity of oil and/or gas wells that have brine and/or two phases of hydrocarbons in a near wellbore region of a hydrocarbon-bearing geological formation.

Summary

The methods of treating a hydrocarbon-bearing formation disclosed herein are typically useful for increasing the permeability in hydrocarbon-bearing formations having at least one of brine (e.g., connate brine and/or water blocking) or two phases of hydrocarbons in the near wellbore region. Treatment of an oil and/or gas well that has brine and/or two phases of hydrocarbons in the near wellbore region using the methods disclosed herein may increase the productivity of the well. Although not wishing to be bound by theory, it is believed that the fluoropolyether silanes disclosed herein generally at least one of adsorb to, chemisorb onto, or react with hydrocarbon-bearing formations under downhole conditions and modify the wetting properties of the rock in the formation to facilitate the removal of hydrocarbons and/or brine. Methods according to the present disclosure are useful for changing the wettability of a variety of materials found in hydrocarbon-bearing formations, including sand, sandstone, and calcium carbonate. Thus, the treatment methods are more versatile than other treatment methods which are effective with only certain substrates (e.g., sandstone). Methods disclosed herein can be carried out with one treatment step (i.e., application of one treatment composition).

In one aspect, the present disclosure provides a method of treating a hydrocarbon- bearing formation, the method comprising: contacting the hydrocarbon-bearing formation with a treatment composition comprising solvent and a fluoropolyether silane, wherein the fluoropolyether silane is selected from the group consisting of: (a) Rf -[Q-XHSi(YVY)₃-W)₁J_n; (b) a compound comprising at least one first divalent unit represented by

Rf-Q-X- O-C=O ; and , at . , least . one of ,

(i) a second divalent unit comprising a pendent -Si(Y')_w(Y)₃__w group; or (ii) a monovalent unit comprising a thioether linkage and at least one terminal -Si(Y')_w(Y)3-_w group; and (c) combinations thereof; wherein each Rf is independently a fluoropolyether group having a weight average molecular weight of at least 750 grams per mole; Rf is a monovalent or divalent fluoropolyether group having a weight average molecular weight of at least 750 grams per mole; each Q is independently a bond, -C(O)-N(R¹)-, or -C(O)-O-;

R and R¹ are each independently hydrogen or alkyl having up to 4 carbon atoms; each X is independently alkylene, arylalkylene, or alkylarylene, wherein alkylene, arylalkylene, and alkylarylene are each optionally interrupted by at least one ether linkage; each X' is independently divalent or trivalent alkylene, arylalkylene, or alkylarylene, wherein alkylene, arylalkylene, and alkylarylene are each optionally interrupted by at least one ester, amide, ether, carbamate, urea, or amine linkage; Y is a hydro lyzable group;

Y' is a non-hydrolyzable group; each w is independently 0, 1, or 2; and m and n are each independently 1 or 2, wherein the method does not include intentionally fracturing the hydrocarbon-bearing formation. In some embodiments, the method further comprises bonding the hydrocarbon- bearing formation with a fluoropolyether siloxane, wherein the fluoropolyether siloxane comprises at least one condensation product of the fluoropolyether silane. In some of these embodiments, the fluoropolyether siloxane shares at least one siloxane bond with the hydrocarbon-bearing formation. In some embodiments, the fluoropolyether siloxane is bonded (e.g., covalently bonded) to an inorganic component of the hydrocarbon-bearing formation.

In another aspect, the present disclosure provides a hydrocarbon-bearing formation comprising a surface, wherein at least a portion of the surface is treated according to a method disclosed herein. In some embodiments, the hydrocarbon-bearing formation shares at least one siloxane bond with a fluoropolyether siloxane, the fluoropolyether siloxane comprising at least one condensation product of the fluoropolyether silane. In some embodiments, the fluoropolyether siloxane is bonded (e.g., covalently bonded) to an inorganic component of the hydrocarbon-bearing formation.

In some embodiments of the foregoing aspects, the hydrocarbon-bearing formation is penetrated by a wellbore, wherein a region near the wellbore (that is, a region within about 25 (in some embodiments, 20, 15, or 10) feet of the wellbore) is treated with the treatment composition. In some of these embodiments, the method further comprises obtaining (e.g., pumping or producing) hydrocarbons from the wellbore after treating the hydrocarbon-bearing formation with the treatment composition. In some embodiments of the foregoing aspects, the hydrocarbon-bearing formation is at least one of not in contact with proppants or free of manmade fractures. In this application:

Terms such as "a", "an" and "the" are not intended to refer to only a singular entity, but include the general class of which a specific example may be used for illustration. The terms "a", "an", and "the" are used interchangeably with the term "at least one".

The phrase "comprises at least one of followed by a list refers to comprising any one of the items in the list and any combination of two or more items in the list. The phrase "at least one of followed by a list refers to any one of the items in the list and any combination of two or more items in the list.

The term "brine" refers to water having at least one dissolved electrolyte salt therein (e.g., having any nonzero concentration, and which may be less than 1000 parts per million by weight (ppm), or greater than 1000 ppm, greater than 10,000 ppm, greater than 20,000 ppm, 30,000 ppm, 40,000 ppm, 50,000 ppm, 100,000 ppm, 150,000 ppm, or even greater than 200,000 ppm).

The term "hydrocarbon-bearing formation" includes both hydrocarbon-bearing formations in the field (i.e., subterranean hydrocarbon-bearing formations) and portions of such hydrocarbon-bearing formations (e.g., core samples).

The term "treating" includes placing a composition within a hydrocarbon-bearing formation using any suitable manner known in the art (e.g., pumping, injecting, pouring, releasing, displacing, spotting, or circulating the fluorinated polymer into a well, wellbore, or hydrocarbon-bearing formation). The term "solvent" refers to a homogeneous liquid material, which may be a single compound or a combination of compounds and which may or may not include water, that is capable of at least partially dissolving the fluoropolyether silane disclosed herein at 25 ⁰C.

"Alkyl group" and the prefix "alk-" are inclusive of both straight chain and branched chain groups and of cyclic groups. Unless otherwise specified, alkyl groups herein have up to 20 carbon atoms. Cyclic groups can be monocyclic or polycyclic and, in some embodiments, have from 3 to 10 ring carbon atoms. "Alkylene" refers to the divalent form or trivalent form of the "alkyl" groups defined above.

"Arylalkylene" refers to an "alkylene" moiety to which an aryl group is attached. The term "aryl" as used herein includes carbocyclic aromatic rings or ring systems, for example, having 1, 2, or 3 rings and optionally containing at least one heteroatom (e.g.,

O, S, or N) in the ring. Examples of aryl groups include phenyl, naphthyl, biphenyl, fluorenyl as well as furyl, thienyl, pyridyl, quinolinyl, isoquinolinyl, indolyl, isoindolyl, triazolyl, pyrrolyl, tetrazolyl, imidazolyl, pyrazolyl, oxazolyl, and thiazolyl.

"Arylene" is the divalent form of the "aryl" groups defined above. "Alkylarylene" refers to an "arylene" moiety to which an alkyl group is attached.

The term "polymer" refers to a molecule having a structure which essentially includes the multiple repetition of units derived, actually or conceptually, from molecules of low relative molecular mass. The term "polymer" encompasses oligomers. Polymers may have repeating units from the same monomer or a combination of monomers. The term "fluoroalkyl group" includes linear, branched, and/or cyclic alkyl groups in which all C-H bonds are replaced by C-F bonds as well as groups in which hydrogen or chlorine atoms are present instead of fluorine atoms provided that up to one atom of either hydrogen or chlorine is present for every two carbon atoms. In some embodiments of fluoroalkyl groups, when at least one hydrogen or chlorine is present, the fluoroalkyl group includes at least one trifluoromethyl group.

The term "productivity" as applied to a well refers to the capacity of a well to produce hydrocarbons (i.e., the ratio of the hydrocarbon flow rate to the pressure drop, where the pressure drop is the difference between the average reservoir pressure and the flowing bottom hole well pressure (i.e., flow per unit of driving force)). The term "bonded" refers to having at least one of covalent bonding, hydrogen bonding, ionic bonding, Van Der Waals interactions, pi interactions, London forces, or electrostatic interactions.

Fracturing a hydrocarbon-bearing formation refers to intentionally injecting a fluid into the hydrocarbon-bearing formation at a rate and pressure sufficient to open a fracture therein. That is, the rate and pressure exceeds the rock strength. Typically, fracturing refers to hydraulic fracturing, and the fracturing fluid is a hydraulic fluid. Fracturing fluids may or may not contain proppants. Unintentional fracturing can sometimes occur, for example, during drilling of a wellbore. Unintentional fractures can be detected (e.g., by fluid loss from the wellbore) and repaired. Typically, fracturing a hydrocarbon-bearing formation refers to intentionally fracturing the formation after the wellbore is drilled. The term "free of manmade fractures" refers to the hydrocarbon-bearing formation being free of fractures made by this process.

All numerical ranges are inclusive of their endpoints and non-integral values between the endpoints unless otherwise stated.

Brief Description of the Drawings For a more complete understanding of the features and advantages of the present disclosure, reference is now made to the detailed description along with the accompanying figures and in which:

Fig. 1 is a schematic illustration of an exemplary embodiment of an offshore oil platform operating an apparatus for progressively treating a near wellbore region according to some embodiments of the present disclosure;

Fig. 2 is a schematic illustration of the flow apparatus used for Examples 1 to 11 and Comparative Examples A and B; and

Fig. 3 is a schematic illustration of a core flood set-up that can be used to evaluate the method disclosed herein in a laboratory.

Detailed Description

In some embodiments, fluoropolyether silanes useful for practicing the present disclosure are represented by the following formula (I):

Rf-[Q-XHSi(YVY)₃-W)₁J_n I. For compounds represented by formula I, Rf is a polyfluoropolyether group having a weight average molecular weight of at least 750 grams per mole. Weight average molecular weights can be measured, for example, by gel permeation chromatography (i.e., size exclusion chromatography) using techniques known in the art. The term "polyfluoropolyether" refers to a compound or group having at least 10 (in some embodiments, at least 11, 12, 13, 14, 15, 16, 17, 18, 19, or even 20) carbon atoms and at least 3 (in some embodiments, at least 4, 5, 6, 7, or even 8) ether linkages, wherein the hydrogen atoms on the carbon atoms are replaced with fluorine atoms. In some embodiments, Rf has up to 100, 110, 120, 130, 140, 150, or even 160 carbon atoms and up to 25, 30, 35, 40, 45, 50, 55, or even 60 ether linkages.

The polyfluoropolyether group Rf can be linear, branched, cyclic, or combinations thereof and can be saturated or unsaturated. Polyfluoropolyether groups include those in which hydrogen or chlorine atoms are present instead of fluorine atoms provided that up to one atom of either hydrogen or chlorine is present for every two carbon atoms. In some embodiments, the polyfluoropolyether group is a perfluoropolyether group (i.e., all of the hydrogen atoms on the carbon atoms are replaced with fluorine atoms). Exemplary perfluoropolyethers include perfluorinated repeating units represented by at least one of -(C_dF_2d)-, -(C_dF_2dO)-, -(CF(Z))-, -(CF(Z)O)-, -(CF(Z)C_dF_2dO)-, -(C_dF_2dCF(Z)O)-, or -(CF₂CF(Z)O)-. In these repeating units, d is typically an integer of 1 to 10. In some embodiments, d is an integer of 1 to 8, 1 to 6, 1 to 4, or 1 to 3. The Z group can be a perfluoroalkyl group optionally interrupted by at least one ether linkage or a perfluoroalkoxy group, each of which may be linear, branched, cyclic, or a combination thereof. The Z group typically has up to 12 (in some embodiments, up to 10, 8, 6, 4, 3, 2, or 1) carbon atoms. In some embodiments, the Z group can have up to 4 (in some embodiments, up to 3, 2, or 1) oxygen atoms; in some embodiments Z has no oxygen atoms. In these perfluoropolyether structures, different repeating units can be combined in a block or random arrangement to form the Rf group. Compounds represented by formula I may contain one polyfluoropolyether group or a mixture of polyfluoropolyether groups. Typically, the compositions will contain a mixture of polyfluoropolyether groups.

In some embodiments, Rf is represented by formula Rf^a-O-(Rf^b-O-)_z(Rf^C)-, wherein R/ is a perfluoroalkyl having 1 to 10 (in some embodiments, 1 to 6, 1 to 4, 2 to 4, or 3) carbon atoms; each R_f ^b is independently a perfluoroalkylene having 1 to 4 (i.e., 1, 2,

3, or 4) carbon atoms; R/ is a perfluoroalkylene having 1 to 6 (in some embodiments, 1 to 4 or 2 to 4) carbon atoms; and z is an integer from 2 to 50 (in some embodiments, 2 to 25, 2 to 20, 3 to 20, 3 to 15, 5 to 15, 6 to 10, or 6 to 8). Representative R/ groups include CF₃-, CF₃CF₂-, CF₃CF₂CF₂-, CF₃CF(CF₃)-, CF₃CF(CF₃)CF₂-, CF₃CF₂CF₂CF₂-, CF₃CF₂CF(CF₃)-, CF₃CF₂CF(CF₃)CF₂-, and CF₃CF(CF₃)CF₂CF₂-. In some embodiments, R_f ^a is CF₃CF₂CF₂-. Representative R_f ^b groups include -CF₂-, -CF(CF₃)-, -CF₂CF₂-, -CF(CF₃)CF₂-, -CF₂CF₂CF₂-, -CF(CF₃)CF₂CF₂-, -CF₂CF₂CF₂CF₂-, and -CF₂C(CFs)₂-. Representative R/ groups include -CF₂-, -CF(CF₃)-, -CF₂CF₂-, -CF₂CF₂CF₂-, and -CF(CF₃)CF₂-. In some embodiments, R_f ^c is -CF(CF₃)-.

In some embodiments, (Rf^b-O-)_z is represented by -[CF₂O]₁[CF₂CF₂O]_J'-, -[CF₂O]₁[CF(CF₃)CF₂O]_J-, -[CF₂O]₁[CF₂CF₂CF₂O]_J-, -[CF₂CF₂O]₁[CF₂O]_J-,

-[CF₂CF₂O]₁[CF(CF₃)CF₂O]_J-, -[CF₂CF₂O]₁[CF₂CF₂CF₂O]_J-,

-[CF₂CF₂CF₂O]₁[CF₂CF(CF₃)O]_J-, and [CF₂CF₂CF₂O]₁[CF(CF₃)CF₂O]_J-, wherein i + j' is an integer of at least 3 (in some embodiments, at least 4, 5, or 6).

In some embodiments, Rf is selected from the group consisting of C₃F₇O(CF(CF₃)CF₂O)_xCF(CF₃)-, C₃F₇O(CF₂CF₂CF₂O)_xCF₂CF₂-, or CF₃O(C₂F₄O)₇CF₂-, wherein x has an average value in a range from 3 to 50 (in some embodiments, 3 to 25, 3 to 15, 3 to 10, 4 to 10, or 4 to 7), and wherein y has an average value in a range from 6 to 50 (in some embodiments, 6 to 25, 6 to 15, 6 to 10, 7 to 10, or 8 to 10). In some of these embodiments, Rf is C₃F₇O(CF(CF₃)CF₂O)_xCF(CF₃)-, wherein x has an average value in a range from 4 to 7. In some embodiments, Rf is selected from the group consisting of CF₃O(CF₂O)_x(C₂F₄O)₇CF₂- and F(CF₂)₃-O-(C₄F₈O)_Z<CF₂)₃-, wherein x, y, and z' each independently has an average value in a range from 3 to 50 (in some embodiments, 3 to 25, 3 to 15, 3 to 10, or even 4 to 10). In these embodiments, n is 1.

In some embodiments, Rf is a divalent polyfluoropolyether group (i.e., n is 2). In some of these embodiments Rf is selected from the group consisting of -CF₂O(CF₂O)_j(C₂F₄O)_kCF2-, -CF₂O(C₂F₄O)₇CF₂-, and

-CF(CF₃)(OCF₂(CF₃)CF)_XO(CF₂)_Z O(CF(CF₃)CF₂O)_X-CF(CF₃)-, wherein j and k each have an average value from 0 to 50 (e.g., 1 to 50, 3 to 30, 3 to 15, or 3 to 10) with the proviso that j + k is at least 6, wherein y' has an average value in a range from 6 to 50 (e.g., 6 to 30, 6 to 15, or 6 to 10), wherein x' has an average value in a range from 0 to 50

(e.g., 1 to 50, 3 to 30, 3 to 15, or 3 to 10), wherein x" has a value in a range from 3 to 50 (e.g., 3 to 30, 3 to 15, or 3 to 10), and wherein z" has a value in a range from 2 to 20 (e.g., 2 to 15, 2 to 10, 2 to 8, 2 to 6, or 4).

In some embodiments, Rf has a weight average molecular weight of at least 750 (in some embodiments at least 850 or even 1000) grams per mole. In some embodiments, Rf has a weight average molecular weight of up to 6000 (in some embodiments, 5000 or even 4000) grams per mole. In some embodiments, Rf has a weight average molecular weight in a range from 750 grams per mole to 5000 grams per mole.

In fluoropolyether silanes represented by Formula I, Q is selected from the group consisting of a bond,-C(O)-N(R¹)-, and -C(O)-O-, wherein R¹ is hydrogen or alkyl of 1 to 4 carbon atoms (e.g., methyl, ethyl, n-propyl, isopropyl, n-butyl, isobutyl, or sec-butyl).

In some embodiments, Q is -C(O)-N(R¹)-. In some embodiments, R¹ is hydrogen or methyl. In some embodiments, R¹ is hydrogen. For embodiments of compositions disclosed herein wherein Q is -C(O)-N(R¹)-, the compositions may be more hydrolytically stable than embodiments wherein Q is -C(O)-O. In fluoropolyether silanes represented by formula I, each X' is independently divalent or trivalent alkylene, arylalkylene, or alkylarylene, wherein alkylene, arylalkylene, and alkylarylene are each optionally interrupted by at least one ester, amide, ether, carbamate, urea, or amine linkage. The term "interrupted" refers to groups in which there is an alkylene, arylene, or arylalkylene segment on each side of the heteroatom (e.g., -CH₂CH₂-O-CH₂CH₂-).In some embodiments, X' is alkylene that is optionally interrupted by at least one carbamate, urea, amide, or ester linkage. In some embodiments, X' is ethylene. In some embodiments, X' is methylene. In some embodiments, X' is a divalent alkylene group, and m is 1. In some embodiments, X' is a trivalent alkylene group, and m is 2. Each Y in formula I is a hydrolysable group, which may be selected from the group consisting of halogen (i.e., -F, -Cl, -Br, or -I), alkoxy (e.g., having 1 to 6, 1 to 4, or 1 to 2 carbon atoms), aryloxy (e.g., phenoxy), acyloxy (e.g., having 1 to 6, 1 to 4, or 1 to 2 carbon atoms), polyalkyleneoxy. "Polyalkyleneoxy" refers to -O-(CHR⁵-CH₂O)_q-R³ wherein R³ is Ci_₄ alkyl, R⁵ is hydrogen or methyl, with at least 70% of the number of R⁵ groups being hydrogen, and q is 1 to 40, or even 2 to 10. In some embodiments, each Y is independently halogen (e.g., Cl or Br), alkoxy having one to six carbon atoms (e.g., having 1 to 4 or 1 to 2 carbon atoms), acyloxy having one to six carbon atoms (e.g., having 1 to 4 or 1 to 2 carbon atoms), or aryloxy (e.g., phenoxy). In some embodiments, Y is methoxy or ethoxy . Hydrolysable groups Y are capable of hydro lyzing, for example, in the presence of water, optionally under acidic or basic conditions, producing groups capable of undergoing a condensation reaction, for example silanol groups. Each Y' is a non-hydrolyzable group (i.e., a group that cannot be hydrolyzed in the presence of water). In some embodiments, Y' is independently alkyl having one to six carbon atoms (e.g., methyl, ethyl, propyl, isopropyl, butyl, isobutyl) or aryl having six to ten carbon atoms (e.g., phenyl). In some embodiments, Y' is alkyl having up to 4, 3, or 2 carbon atoms. In formula I, w is 0, 1, or 2. In some embodiments, w is 0. In some embodiments, w is 1. In some embodiments, fluoropolyether silanes useful for practicing the present disclosure are represented by formula Rf-{C(O)-N(R¹)-X"-[OC(O)-V'-Si(Y^>)_w(Y)₃-w]m}n or Rf-{C(O)-N(R¹)-X"-[OC(O)NH-V'-Si(Y^>)_w(Y)₃-w]m}n. In these embodiments, Rf is a polyfluoropolyether group that is defined as in any of the above embodiments of Rf , and Y and Y' are as defined in any of the above embodiments of Y and Y'. In these formulas, X" is a divalent or trivalent group selected from the group consisting of alkylene, arylalkylene, and alkylarylene, wherein alkylene, arylalkylene, and alkylarylene are each optionally interrupted by at least one ether linkage (i.e., -O-). In some embodiments, X" is alkylene. In some embodiments, X" is ethylene. In some embodiments, X" is methylene. In some embodiments, X" is a divalent alkylene group, and m is 1. In some embodiments, X" is a trivalent alkylene group, and m is 2. In these formulas, V is alkylene that is optionally interrupted by at least one ether linkage (i.e., -O-) or amine (i.e., -N(R¹)-, wherein R¹ is as defined above) linkage. In some embodiments, V is alkylene having from 2 to 4 (i.e., 2, 3, or 4) (in some embodiments, 2) carbon atoms.

In compounds represented by formula Rf -[Q-X'-(Si(Y')_w(Y)3-_w)m]n, when at least one of m or n is 2, and in compounds represented by formula Rf-{C(O)-N(R¹)-X"-[OC(O)-V-Si(Y^>)_w(Y)₃._w]_m}_n θr

Rf-{C(O)-N(R¹)-X"-[OC(O)NH-V'-Si(Y^>)_w(Y)₃._w]_m}_n, when at least one of m or n is 2, each Rf, R¹, Q, X, X", and V group is independently selected.

The compounds represented by Formula Rf-[Q-X'-(Si(Y')_w(Y)3__w)_m]_n can be prepared, for example, from a polyfluoropolyether methyl ester of formula

Rf-[C(O)-OCH₃J_n, wherein n is 1 or 2. Monovalent methyl esters of this formula can be prepared, for example, by polymerization of hexafluoropropylene oxide using known methods to form a perfluoropolyether terminated with a fluorocarbonyl group (i.e., -C(O)F). This material can be vacuum distilled to remove components having a molecular weight less than 750 (in some embodiments, less than 800, 900, or 1000) grams per mole. The fluorocarbonyl group can be converted to a alkoxycarbonyl group (e.g., a methyl ester) by conventional methods, for example, by esterification with methanol. Divalent methyl esters of formula Rf-[C(O)-OCHs]_n can be prepared, for example, by known methods or can be obtained commercially (e.g., from Solvay Solexis, Houston, TX, available under the trade designation "FOMBLIN ZDEAL"). Known methods for preparing these compounds include, for example, polymerization of hexafluoropropylene oxide in the presence of a difunctional fluorinated acid fluoride; (see, e.g., U.S. Pat. No.

4,647,413 (Savu), incorporated herein by reference for these methods).

Methyl esters of formula Rf-[C(O)-OCHs]_n can then be reacted, for example, with an amino alcohol of Formula NHR¹-X"-(0H)_m, wherein R¹, X", and m are as defined above, using methods described on column 16, lines 37-62 of U. S. Pat. No. 7,094,829 (Audenaert et al.), the disclosure of which method is incorporated herein by reference, to provide an alcohol of formula Rf-[C(0)-NHR¹-X"-(0H)_m]_n. Many amino alcohols are available commercially. In some embodiments, the amino alcohol is ethanol amine. In some embodiments, the amino alcohol is 3-amino-l,2-propanediol. In other embodiments, methyl esters of formula Rf-[C(O)-OCHs]_n can then be reacted, for example, with aminosilanes.

Hydroxyl-substituted compound of formula Rf-[C(0)-NHR¹-X"-(0H)_m]_n can be treated with, for example, a haloalkyl silane (e.g., chloropropyltrimethoxysilane), an isocyantoalkyl silane (e.g., 3-isocyanatopropyltriethoxysilane), or an epoxy silane (e.g., gamma-glycidoxypropyltrimethoxysilane). The reaction with a haloalkyl silane can be carried out, for example, by first treating the hydroxyl-substituted compound with a base (e.g., sodium methoxide or sodium tert-butoxide) in a suitable solvent (e.g., methanol), optionally at an elevated temperature (e.g., up to the reflux temperature of the solvent), followed by heating (e.g., at up to 100 ⁰C, 80 ⁰C, or 70 ⁰C) the resulting alkoxide with the haloalkyl silane. The reaction of a hydroxyl-substituted compound represented by formula Rf -[C(0)-NHR¹-X"-(0H)_m]_n with an isocyantoalkyl silane can be carried out, for example, in a suitable solvent (e.g., methyl ethyl ketone), optionally at an elevated temperature (e.g., the reflux temperature of the solvent), and optionally in the presence of a catalyst (e.g., stannous octanoate or tin(II) 2-ethylhexanoate).

In some embodiments, fluoropolyether silanes useful for practicing the present disclosure comprise at least one first divalent unit represented by formula II:

Rf-Q-X- 0-C=O

Rf is a polyfluoropolyether group having a weight average molecular weight of at least 750 grams per mole. The term "polyfluoropolyether" has the same meaning as described above for silanes represented by formula I. Compounds comprising a divalent unit represented by Formula II may contain one polyfluoropolyether group or a mixture of polyfluoropolyether groups. Typically, the compositions will contain a mixture of polyfluoropolyether groups.

In some embodiments, Rf is a perfluoropolyether group. In some embodiments, Rf is represented by formula R_f ^a-O-(R_f ^b-O-)_z(R_f ^C)-,wherein R/ is a perfluoroalkyl having 1 to 10 (in some embodiments, 1 to 6, 1 to 4, 2 to 4, or 3) carbon atoms; each Rf^b is independently a perfluoroalkylene having 1 to 4 (i.e., 1, 2, 3, or 4) carbon atoms; R/ is a perfluoroalkylene having 1 to 6 (in some embodiments, 1 to 4 or 2 to 4) carbon atoms; and z is an integer from 2 to 50 (in some embodiments, 2 to 25, 2 to 20, 3 to 20, 3 to 15, 5 to 15, 6 to 10, or 6 to 8). Representative R/ groups include CF₃-, CF₃CF₂-, CF₃CF₂CF₂-, CF₃CF(CF₃)-,

CF₃CF(CF₃)CF₂-, CF₃CF₂CF₂CF₂-, CF₃CF₂CF(CF₃)-, CF₃CF₂CF(CF₃)CF₂-, and CF₃CF(CF₃)CF₂CF₂-. In some embodiments, R/ is CF₃CF₂CF₂-. Representative R_f ^b groups include -CF₂-, -CF(CF₃)-, -CF₂CF₂-, -CF(CF₃)CF₂-, -CF₂CF₂CF₂-, -CF(CF₃)CF₂CF₂-, -CF₂CF₂CF₂CF₂-, and -CF₂C(CF₃)₂-. Representative R_f ^c groups include -CF₂-, -CF(CF₃)-, -CF₂CF₂-, -CF₂CF₂CF₂-, and CF(CF₃)CF₂-. In some embodiments, R/ is -CF(CF₃)-.

In some embodiments, (Rf^b-O-)_z is represented by -[CF₂O]₁[CF₂CF₂O]_J'-, -[CF₂O]₁[CF(CF₃)CF₂O]_J-, -[CF₂O]₁[CF₂CF₂CF₂O]_J-, -[CF₂CF₂O]₁[CF₂O]_J-, -[CF₂CF₂O]₁[CF(CF₃)CF₂O]_J-, -[CF₂CF₂O]₁[CF₂CF₂CF₂O]_J-, -[CF₂CF₂CF₂O]₁[CF₂CF(CF₃)O]_J-, and [CF₂CF₂CF₂O]₁[CF(CF₃)CF₂O]_J-, wherein i + j' is an integer of at least 3 (in some embodiments, at least 4, 5, or 6).

In some embodiments, Rf is selected from the group consisting of C₃F₇O(CF(CF₃)CF₂O)_xCF(CF₃)-, C₃F₇O(CF₂CF₂CF₂O)_xCF₂CF₂-, or CF₃O(C₂F₄O)₇CF₂-, wherein x has an average value in a range from 3 to 50 (in some embodiments, 3 to 25, 3 to 15, 3 to 10, 4 to 10, or 4 to 7), and wherein y has an average value in a range from 6 to 50 (in some embodiments, 6 to 25, 6 to 15, 6 to 10, 7 to 10, or 8 to 10). In some of these embodiments, Rf is C₃FyO(CF(CF₃)CF₂θ)_xCF(CF₃)-, wherein x has an average value in a range from 4 to 7. In some embodiments, Rf is selected from the group consisting of CF₃O(CF₂O)_x(C₂F₄O)₇CF₂- and F(CF₂)3-O-(C₄F₈O)_Z<CF₂)3-, wherein x, y, and z' each independently has an average value in a range from 3 to 50 (in some embodiments, 3 to 25, 3 to 15, 3 to 10, or even 4 to 10).

In divalent units represented by Formula II, Q is selected from the group consisting of a bond,-C(O)-N(R¹)-, and -C(O)-O-, wherein R¹ is hydrogen or alkyl of 1 to 4 carbon atoms (e.g., methyl, ethyl, n-propyl, isopropyl, n-butyl, isobutyl, or sec-butyl). In some embodiments, Q is -C(O)-N(R¹)-. In some embodiments, R¹ is hydrogen or methyl. In some embodiments, R¹ is hydrogen. For embodiments of compositions disclosed herein wherein Q is -C(O)-N(R¹)-, the compositions may be more hydrolytically stable than embodiments wherein Q is -C(O)-O.

In divalent units represented by Formula II, R is hydrogen or alkyl of 1 to 4 carbon atoms (e.g., methyl, ethyl, n-propyl, isopropyl, n-butyl, isobutyl, or sec-butyl). In some embodiments, R is hydrogen or methyl.

In divalent units represented by Formula II, X is selected from the group consisting of alkylene, arylalkylene, and alkylarylene, wherein alkylene, arylalkylene, and alkylarylene are each optionally interrupted by at least one ether linkage. In some embodiments, X is alkylene. In some embodiments, X is ethylene. In some embodiments, X is methylene.

In fluoropolyether silanes useful for practicing the present disclosure, when more than one first divalent unit of Formula II is present, each Rf, Q, R, R¹, and X group is independently selected. In some embodiments, the first divalent unit of Formula II is represented by formula:

Rf-C(O)-N(R¹) -X- 0-C=O

•> wherein Rf, R, R¹, and X are as defined above. In some embodiments, the number of units represented by formula II is in a range from 1 to 100 (in some embodiments from 1 to 20). In some embodiments, the units represented by formula II are present in a range from 25 to 99 (in some embodiments, from 35 to 99, from 50 to 99, from 60 to 98, from 75 to 97, or even from 85 to 97) percent based on the total weight of the fluoropolyether silane. In some embodiments, the polymeric fluorinated composition contains at least 5 mole % (based on total moles of monomers) of Y groups. In some embodiments, the fluoropolyether silane is a polymer having a weight average molecular weight in a range from 2000 to 100,000, from 3,500 to 100,000, or from 10,000 to 75,000 grams per mole or in a range from 2000 to 20,000, or from 2,000 to 10,000 grams per mole. It will be appreciated by one skilled in the art that such polymers can exist as a mixture of compositions and molecular weights.

For embodiments of fluoropolyether silanes disclosed herein that include a first divalent unit represented by Formula II, the fluoropolyether silane further comprises at least one of (i) a second divalent unit comprising a pendent -Si(Y')_w(Y)₃__w group; or (ii) a monovalent unit comprising a thioether linkage and at least one terminal -Si(Y')_w(Y)₃__w group. The phrase at least one of (i) or (ii) used herein means that the fluoropolyether silane comprises (i) only, (ii) only, or both (i) and (ii). In some embodiments, the fluoropolyether silane comprises both (i) and (ii). In these formulas Y, Y', and w are as defined in any of the embodiments described above for Y, Y', and w.

In some embodiments, the fluoropolyether silane useful for practicing the present disclosure comprises a second divalent unit comprising a pendent -Si(Y')_w(Y)3-_w group. In some of these embodiments, the second divalent unit is represented by -[CH₂-CH(-Si(Y')_w(Y)3-w)]- or the following formula (III):

wherein Y, Y', and w are as defined above, each V is independently alkylene that is optionally interrupted by at least one ether linkage or amine linkage, and each R² is as defined above in any of the embodiments of R. The term "interrupted" refers to groups in which there is an alkylene segment on each side of the heteroatom (e.g., -CH₂CH₂-O- CH₂CH₂-). In some embodiments, V is alkylene (e.g., having up to 6, 5, 4, or 3 carbon atoms). In some embodiments, the second divalent unit is represented by formula -[CH₂-CH(-Si(Y')_w(Y)3-w)]-, wherein Y, Y', and w are as defined above. A combination of second divalent units of formulas III and -[CH₂-CH(-Si(Y')_w(Y)₃__w)]- may also be useful. In some embodiments, the number of divalent units represented by formula III or

-[CH₂-CH(-Si(Y')_w(Y)3-w)]- is in a range from 0 to 100 (or even from 0 to 20). In some embodiments, the second divalent units are present in a range from 1% to 30% by weight (in some embodiments, from 2 to 30, from 3 to 25, or even from 3 to 15 percent) based on the total weight of the fluoropolyether silane. In some embodiments, the fluoropolyether silane comprises a monovalent unit comprising a thioether linkage and at least one terminal -Si(Y')_w(Y)3__w group, for example, a chain-terminating group represented by the following formula (IV):

-S-W-[SiY₃-w(Y')w]m IV, wherein Y, Y', and w are as defined above in any of their various embodiments, m is 1 or 2, and W is a divalent or trivalent linking group selected from the group consisting of alkylene, arylalkylene, and arylene, wherein alkylene is optionally interrupted by at least one ether linkage, ester linkage, carbamate, urea, or amide linkage. In some embodiments, W is alkylene that is optionally interrupted by at least one carbamate, urea, amide, or ester linkage. In some embodiments, W is ethylene or propylene. In some embodiments, W is a divalent alkylene group, and m is 1. In some embodiments, W is a trivalent alkylene group, and m is 2. In some embodiments, the monovalent unit comprising a thioether linkage and at least one terminal -Si(Y')_w(Y)3__w group is represented by a formula selected from the group consisting of:

-S-C_bH_2bOC(O)NHCbH_2b-Si(Y')w(Y)3-w; and

-S-C_bH_2b.₁[OC(O)NHC_bH_2b-Si(Y^>)_w(Y)₃.w]2, wherein each b is independently an integer from 1 to 5 (in some embodiments, 2 to 3). In some embodiments, the monovalent unit is -S-C_bH_2bOC(O)NHC_bH_2b-Si(Y')_w(Y)3__w, wherein each b is independently 2 or 3. In some embodiments, the monovalent unit is -S-C_bH_2b_i [OC(O)NHC_bH_2b-Si(Y')_w(Y)₃-w]2, wherein each b is independently 2 or 3. Fluoropolyether silanes useful for practicing the present disclosure, in some embodiments, may have both a second divalent unit comprising a pendent -Si(Y')_w(Y)₃__w group and a monovalent unit comprising a terminal -Si(Y')_w(Y)₃__w group and/or may have two different second divalent units. In these embodiments, each Y, Y', V, W, and R² is independently selected.

In some embodiments, fluoropolyether silanes useful for practicing the present disclosure further comprise at least one divalent unit represented by the following formula (V):

wherein each R² is independently selected from the group consisting of hydrogen and alkyl having from 1 to 4 carbon atoms (e.g., methyl, ethyl, n-propyl, isopropyl, n-butyl, isobutyl, or sec -butyl), and wherein each R is independently alkyl having from 1 to 30 (in some embodiments, 1 to 25, 1 to 20, 1 to 10, 4 to 25, 8 to 25, or even 12 to 25) carbon atoms. In some embodiments, R² is selected from the group consisting of hydrogen and methyl. In some embodiments, R is selected from the group consisting of hexadecyl and octadecyl.

In some embodiments, fluoropolyether silanes useful for practicing the present disclosure further comprise at least one fluoroalkyl divalent unit represented by formula:

RfHC_qH_2q) -o-c=o

Each Rf¹ is independently a fluoroalkyl group having from 3 to 12 (i.e., 3, 4, 5, 6, 7, 8, 9, 10, 11, or 12) carbon atoms. In some embodiments, each Rf¹ is independently a perfluoroalkyl group having from 3 to 6 (e.g., perfluoro-n-hexyl, perfluoro-n-pentyl, perfluoroisopentyl, perfluoro-n-butyl, perfluoroisobutyl, perfluoro-sec -butyl, perfluoro- tert-buty\, perfluoro-n-propyl, or perfluoroisopropyl). In some embodiments, Rf¹ is perfluorobutyl (e.g., perfluoro-n-butyl). In some embodiments, Rf¹ is perfluoropropyl (e.g., perfluoro-n-propyl). R⁴ and R⁵ are each independently hydrogen or alkyl having from 1 to 4 carbon atoms (e.g., methyl, ethyl, n-propyl, isopropyl, n-butyl, isobutyl, or sec-butyl). In some embodiments, R⁴ is selected from the group consisting of methyl and ethyl. In some embodiments, R⁵ is selected from the group consisting of hydrogen and methyl.

Each p is independently an integer having a value from 2 to 11 (i.e., 2, 3, 4, 5, 6, 7, 8, 9, 10, or 11).

Each q is independently an integer having a value from 1 to 20 (i.e., 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18, 19, or 20).

In some embodiments, fluoropolyether silanes useful for practicing the present disclosure comprise a divalent unit represent by Formula II and a divalent unit represent by Formula VI:

Rf^!

VI. The ratio of divalent units represent by Formula II to divalent units represent by Formula VI may be in a range from 99:1 to 1 :99 (in some embodiments, 95:5 to 5:95, 90:10 to 10:90, 85:15 to 15:85, 80:20 to 20:80, 75:25 to 25:75, or 90:10 to 50:50). In some embodiments, the divalent unit represented by Formula VI is represented by formula:

wherein R" and R" are each independently hydrogen or alkyl having from 1 to 4 carbon atoms. In some embodiments, each R" is independently hydrogen or methyl. In some embodiments, R" is methyl or ethyl.

In some embodiments, fluoropolyether silanes useful for practicing the present disclosure that comprise a divalent unit represent by Formula II further comprise at least one divalent unit represented by formula -[CH₂-C(Cl₂)]- or -[CH₂-CHCl]-.

In some embodiments, fluoropolyether compounds useful for practicing the present disclosure (e.g., those comprising a divalent unit represented by Formula II) comprise a monovalent unit selected from the group consisting of -S-C_tH_2t+1 and -S-C_rH_2r_(_s-i)-(A)_s, wherein t is an integer having a value from 4 to 22; r is an integer having a value from 2 to

10 (in some embodiments, 2 to 6 or even 2 to 4); s is an integer having a value from 1 to 4;

0 0 0 and A is selected from the group consisting of -OH, -COOY , and -SO₃Y , wherein Y is selected from the group consisting of hydrogen, alkyl, and a counter cation (e.g., alkali metal (e.g., sodium, potassium, and lithium), alkaline earth metal (e.g., calcium or magnesium), ammonium, alkyl ammonium (e.g., tetraalkylammonium), and five to seven membered heterocyclic groups having a positively charged nitrogen atom (e.g, a pyrrolium ion, pyrazolium ion, pyrrolidinium ion, imidazolium ion, triazolium ion, isoxazolium ion, oxazolium ion, thiazolium ion, isothiazolium ion, oxadiazolium ion, oxatriazolium ion, dioxazolium ion, oxathiazolium ion, pyridinium ion, pyridazinium ion, pyrimidinium ion, pyrazinium ion, piperazinium ion, triazinium ion, oxazinium ion, piperidinium ion, oxathiazinium ion, oxadiazinium ion, and morpholinium ion)). In some embodiments, Y² is alkyl having from 4 to 22, 8 to 22, or 12 to 22 carbon atoms. In some embodiments, compositions according to the present invention comprise a monovalent unit selected from the group consisting of -S-CtH_2t+i and -S-C₁H₂I-A, wherein t, r, and A are as defined above. In some embodiments, the chain-terminating group is -S-CtH_2t+l5 wherein t has a value from 4 to 22 (in some embodiments, 8 to 22, or even 12 to 22). In some embodiments, the fluoropolyether silane is represented by formula

wherein R, Rf, Rf¹, Q, X, Y, Y', V, W, w, p, q, R⁴, R⁵, and R² are as defined above; m is 1 or 2; a' is a value from 1 to 100 inclusive; b', c', and e' are each independently values from 0 to 100 inclusive, and d' is a value from 0 to 1 inclusive, with the proviso that at least b' or d' is at least 1. Each of the units is independently in random order.

In some embodiments of fluoropolyether silanes useful for practicing the present disclosure that contain a divalent unit represented by Formula II, the first and second divalent groups and any other divalent units present are randomly connected. These fluoropolyether compounds may be prepared, for example, by reacting a mixture containing at least first and second components typically in the presence of a chain transfer agent and an initiator. By the term "reacting" it is meant forming a composition that includes at least one identifiable structural element due to each of the first and second components. Depending on the stoichiometry of the reaction, an oligomer or polymer may be formed. Typically the polymer or oligomer has a distribution of molecular weights and compositions.

In some embodiments, the first component is represented by Formula Ha: Rf-Q-X-O-C(O)-C(R)=CH₂ Ha, wherein Rf, Q, R, and X are as defined above for a divalent unit of Formula II. In some embodiments, the compound of Formula Ha is Rf-C(O)-N(R^-X-O-C(O)-C(R)=CH₂, wherein R¹ is as defined above for a compound of Formula II.

For embodiments in which the fluoropolyether silane comprises a second divalent unit comprising a pendent -Si(Y')_w(Y)₃__w group, a monomer represented by formula Ha can be reacted, for example, with a monomer represented by formula CH₂=C(R¹)-C(O)-X-W-Si(Y')w(Y)3-w or CH₂=C(R¹)- S i(Y)_w(Y)₃-w wherein R¹, W, X, Y, Y', and w are as defined above in any of their various embodiments. Some monomers represented by these formulas are commercially available (e.g., CH₂=C(CH₃)C(O)OCH₂CH₂CH₂Si(OCHs)₃ (available, for example, from Union Carbide, New York, NY, under the trade designation "A-174"), vinyltrichlorosilane, vinyltrimethoxysilane, and vinyltriethoxysilane); others can be made by conventional synthetic methods.

The component represented by Formula Ha can be prepared, for example, using known methods. For example, hexafluoropropylene oxide can be polymerized using known methods to form a perfluoropolyether terminated with a fluorocarbonyl group (i.e., -C(O)F). This material can be vacuum distilled to remove components having a molecular weight less than 750 (in some embodiments, in some embodiments, less than 800, 900, or 1000) grams per mole. The fluorocarbonyl group can optionally be converted to a carboxy or alkoxycarbonyl group by conventional methods. Typically, conversion to an alkoxycarbonyl terminated perfluoropolyether (e.g., conversion to a methyl ester of formula Rf-C(O)-OCH₃) is carried out.

A methyl ester of formula Rf-C(O)-OCH₃, an acid fluoride of formula Rf-C(O)-F, or a carboxylic acid of formula Rf-C(O)-OH can then be converted to a compound of Formula Ha using a number of conventional methods. For example, a perfluoropolyether monomer of formula Rf-(CO)NHCH₂CH₂O(CO)C(R)=CH₂ can be prepared by first reacting Rf-C(O)-OCH₃, for example, with ethanolamine to prepare alcohol-terminated Rf-(CO)NHCH₂CH₂OH, which can then be reacted with methacrylic acid, methacrylic anhydride, acrylic acid or acryloyl chloride to prepare the compound of Formula Ha, wherein R is methyl or hydrogen, respectively. Other amino alcohols (e.g., amino alcohols of formula NR¹HXOH) can be used in this reaction sequence to provide compounds of Formula Ha, wherein Q is -C(O)-N(R¹)-, and R¹ and X are as defined above. In further examples, an ester of formula Rf-C(O)-OCH₃ or a carboxylic acid of formula Rf-C(O)-OH can be reduced using conventional methods (e.g., hydride, for example sodium borohydride, reduction) to an alcohol of formula Rf-CH₂OH. The alcohol of formula Rf-CH₂OH can then be reacted with methacryloyl chloride, for example, to provide a perfluoropoly ether monomer of formula Rf-CH₂O(CO)C(R)=CH₂.

Examples of suitable reactions and reagents are further disclosed, for example, in the European patent EP 870 778 Al, published October 14, 1998, and U.S. Patent No. 3,553,179 (Bartlett et al.), the disclosures of which, relating to reagents and reaction conditions for preparing compounds of Formula Ha, are incorporated herein by reference. The reaction of at least one first component and at least one second component is typically carried out in the presence of a free-radical initiator. Free radical initiators such as those widely known and used in the art may be used to initiate polymerization of the components. Exemplary free-radical initiators are described in U. S. Pat. No. 6,995,222 (Buckanin et al.), the disclosure of which is incorporated herein by reference. Free-radical reactions may be carried out in any suitable solvent at any suitable concentration, (e.g., from about 5 percent to about 90 percent by weight based on the total weight of the reaction mixture). Illustrative examples of suitable solvents include ethers (e.g., diethyl ether, glyme, diglyme, and diisopropyl ether), esters (e.g., ethyl acetate and butyl acetate), alcohols (e.g., ethanol and isopropyl alcohol), ketones (e.g., acetone, methyl ethyl ketone and methyl isobutyl ketone), halogenated solvents (e.g., methylchloroform, 1 , 1 ,2-trichloro- 1 ,2,2-trifluoroethane, trichloroethylene, trifluorotoluene, and hydrofluoroethers available, for example, from 3M Company, St. Paul, MN under the trade designations "HFE-7100" and "HFE-7200"), and mixtures thereof. Polymerization can be carried out at any temperature suitable for conducting an organic free-radical reaction. Temperature and solvent for a particular use can be selected by those skilled in the art based on considerations such as the solubility of reagents, temperature required for the use of a particular initiator, and desired molecular weight. While it is not practical to enumerate a particular temperature suitable for all initiators and all solvents, generally suitable temperatures are in a range from about 30 ⁰C to about 200 ⁰C (in some embodiments, from about 40 ⁰C to about 100 ⁰C, or even from about 50 ⁰C to about 80 ⁰C). Fluoropolyether silanes useful for practicing the present invention may have a chain-terminating group represented by formula IV. A chain-terminating group of formula IV may be incorporated into the fluoropolyether silane, for example, by adding a chain-transfer agent of the formula HS-W-SiY₃__w(Y')_w to the reaction mixture comprising the monomer represented by formula Ha. For the chain-transfer agent represented by formula HS-W-SiY3-_w(Y')w the groups W, Y, Y', and w may have any definition described above for monovalent units represented by formula IV. Some chain-transfer agents of formula HS-W-SiY3__w(Y')_w are commercially available (e.g., 3- mercaptopropyltrimethoxysilane (available, for example, from HuIs America, Inc., Somerset, N.J., under the trade designation "DYNASYLAN")); others can be made by conventional synthetic methods. A chain-terminating group of formula IV can also be incorporated into a fluoropolyether silane as disclosed herein by including in the free- radical reaction mixture a hydroxyl-functional chain-transfer agent (e.g., 2- mercaptoethanol, 3-mercapto-2-butanol, 3-mercapto-2-propanol, 3-mercapto-l-propanol, 3-mercapto-l,2-propanediol) and subsequent reaction of the hydroxyl functional group with, for example, a chloroalkyltrialkoxysilane or isocyanatoalkyltrialkoxy silane. In a reaction mixture to make a fluoropolyether silane disclosed herein, a single chain transfer agent or a mixture of different chain transfer agents may be used to obtain the desired molecular weight of the fluoropolyether silane. Other chain transfer agents that may be useful in the preparation of compositions according to the present invention include amino-substituted mercaptans (e.g., 2- mercaptoethylamine); difunctional mercaptans (e.g., di(2-mercaptoethyl)sulfϊde); and aliphatic mercaptans (e.g., octylmercaptan, dodecylmercaptan, and octadecylmercaptan). In some embodiments, the chain-transfer agent is an aliphatic mercaptan, and the monovalent unit is represented by formula -S-CtH_2t+l5 wherein t is an integer from 4 to 22 (in some embodiments, 8 to 22 or even 12 to 22).

Adjusting, for example, the concentration and activity of the initiator, the concentration of each of the first component of Formula Ha, the second component (in some embodiments), the temperature, the concentration of the chain transfer agent, and the solvent using techniques known in the art can control the molecular weight of a polyacrylate copolymer. To prepare some fluoropolyether compounds that contain a first divalent unit represented by Formula II useful for practicing the present disclosure other components (e.g., monomers) may be included. In some embodiments, an acrylate or methacrylate monomer represented by Formula Via:

O R⁴ O

RP -S-N-CCH^ -0-C-C(R⁵) z CH₂ ° Via is added, wherein Rf¹, R⁴, R⁵, and p are as defined above. In some embodiments an acrylate or methacrylate represented by Formula Va:

⁰

R³ -0-C-C=CH₇

I

^R2 Va, is added, wherein R² and R³ are as defined above. In some embodiments, vinylidene chloride or vinyl chloride is added. In some embodiments, an acrylate or methacrylate of formula

Rf¹-(CH₂)_q-OC(O)-C(R⁵)=CH₂ is added, wherein Rf¹, q, and R⁵ are as defined above.

Fluorinated free-radically polymerizable acrylate monomers of formula Via, and methods for their preparation, are known in the art; (see, e.g., U.S. Pat. Nos. 2,803,615 (Albrecht et al.) and 6,664,354 (Savu et al.), the disclosures of which, relating to free- radically polymerizable monomers and methods of their preparation, are incorporated herein by reference). Methods described in these references for making nonafluorobutanesulfonamido group-containing structures can be used to make heptafluoropropanesulfonamido groups by starting with heptafluoropropanesulfonyl fluoride, which can be made, for example, by the methods described in Examples 2 and 3 of U.S. Pat. No. 2,732,398 (Brice et al.), the disclosure of which is incorporated herein by reference. Methods for making other fluorinated acrylates and methacrylates are known; (see, e.g., EP1311637 Bl , published April 5, 2006, and incorporated herein by reference for the disclosure of the preparation of 2,2,3,3,4,4,4-heptafluorobutyl 2-methylacrylate).

Other fluorinated acrylates and methacrylates are available, for example, from commercial sources (e.g., 3,3,4,4, 5,5, 6,6, 6-nonafluorohexyl acrylate from Daikin Chemical Sales, Osaka, Japan and 3, 3,4,4,5, 5,6, 6,6-nonafluorohexyl 2-methylacrylate from Indofine Chemical Co., Hillsborough, NJ).

For embodiments in which the fluoropolyether silane comprises a third divalent unit represented by formula V, a monomer selected from alkyl acrylates and methacrylates (e.g., octadecyl methacrylate, lauryl methacrylate, butyl acrylate, isobutyl methacrylate, ethylhexyl acrylate, ethylhexyl methacrylate, methyl methacrylate, hexyl acrylate, heptyl methacrylate, cyclohexyl methacrylate, or isobornyl acrylate) can be added to the reaction mixture comprising the monomer represented by formula II. Some of these compounds (e.g., methyl methacrylate, butyl acrylate, hexadecyl methacrylate, octadecyl methacrylate, stearyl acrylate, behenyl methacrylate) are available, for example, from several chemical suppliers (e.g., Sigma-Aldrich Company, St. Louis, MO; VWR International, West Chester, PA; Monomer-Polymer & Dajac Labs, Festerville, PA; Avocado Organics, Ward Hill, MA; and Ciba Specialty Chemicals, Basel, Switzerland) or may be synthesized by conventional methods. Some compounds of formula Va are available as single isomers (e.g., straight-chain isomer) of single compounds. Other compounds of formula Va are available, for example, as mixtures of isomers (e.g., straight-chain and branched isomers), mixtures of compounds (e.g., hexadecyl acrylate and octadecylacrylate), and combinations thereof.

Fluoropolyether silanes useful for practicing the present disclosure may contain other units, typically in weight percents up to 20, 15, 10, or 5 percent, based on the total weight of the fluoropolyether silane. These units may be incorporated into the compound by selecting additional components for the free-radical reaction such as allyl esters (e.g., allyl acetate and allyl heptanoate); vinyl ethers or allyl ethers (e.g., cetyl vinyl ether, dodecylvinyl ether, 2-chloroethylvinyl ether, or ethylvinyl ether); alpha-beta unsaturated nitriles (e.g., acrylonitrile, methacrylonitrile, 2-chloroacrylonitrile, 2-cyanoethyl acrylate, or alkyl cyanoacrylates); alpha-beta-unsaturated carboxylic acid derivatives (e.g., allyl alcohol, allyl glycolate, acrylamide, methacrylamide, n-diisopropyl acrylamide, or diacetoneacrylamide), styrene and its derivatives (e.g., vinyltoluene, alpha-methylstyrene, or alpha-cyanomethyl styrene); olefmic hydrocarbons which may contain at least one halogen (e.g., ethylene, propylene, isobutene, 3-chloro-l-isobutene, butadiene, isoprene, chloro and dichlorobutadiene, 2,5-dimethyl-l,5-hexadiene, and vinyl and vinylidene chloride); and hydroxyalkyl-substituted polymerizable compounds (e.g., 2-hydroxyethyl methacrylate). In some embodiments, the fluoropolyether silane are free of anionic groups (e.g., carboxylates, sulfates, sulfonates, phosphates, and phosphonates). In some embodiments, the fluoropolyether silanes are free of cationic groups (e.g., quaternary amine groups), and in other embodiments, the fluoropolyether silanes are free of poly(alkyleneoxy) groups. In some embodiments, the fluoropolyether silanes are free of anionic groups, cationic groups, and poly(alkyleneoxy) groups. Unexpectedly, fluoropolyether silanes that are free of such water-solubilizing groups effectively change the permeability of sand and calcium carbonate to water and liquid hydrocarbons.

Typically, in treatment compositions useful for practicing the methods described herein, the fluoropolyether silane is present in the treatment composition at at least 0.01, 0.015, 0.02, 0.025, 0.03, 0.035, 0.04, 0.045, 0.05, 0.055, 0.06, 0.065, 0.07, 0.075, 0.08, 0.085, 0.09, 0.095, 0.1, 0.15, 0.2, 0.25, 0.5, 1, 1.5, 2, 3, 4, or 5 percent by weight, up to 5, 6, 7, 8, 9, or 10 percent by weight, based on the total weight of the treatment composition. For example, the amount of the fluoropolyether silane in the treatment compositions may be in a range of from 0.01 to 10, 0.1 to 10, 0.1 to 5, 1 to 10, or even in a range from 1 to 5 percent by weight, based on the total weight of the treatment composition. Lower and higher amounts of the fluoropolyether silane in the treatment compositions may also be used, and may be desirable for some applications.

Treatment compositions useful in practicing the present disclosure comprise solvent. Examples of useful solvents for any of these methods include organic solvents, water, easily gasified fluids (e.g., ammonia, low molecular weight hydrocarbons, and supercritical or liquid carbon dioxide), and combinations thereof. In some embodiments, the organic solvent is water-miscible. Examples of organic solvents useful for practicing the methods disclosed herein include polar solvents such as alcohols (e.g., methanol, ethanol, isopropanol, propanol, or butanol), glycols (e.g., ethylene glycol or propylene glycol), glycol ethers (e.g., ethylene glycol monobutyl ether or those glycol ethers available under the trade designation "DOWANOL" from Dow Chemical Co., Midland, MI), ketones (e.g., acetone, methyl ethyl ketone, 4-methyl-2-pentanone, 3-methyl-2- pentanone, 2-methyl-3-pentanone, and 3,3-dimethyl-2-butanone), esters (e.g., ethyl acetate, methyl formate, propyl acetate, and butyl acetate); ethers (e.g, diethyl ether, tetrahydrofuran (THF), diisopropyl ether, p-dioxane, tert-butyl methyl ether, and dipropyleneglycol monomethylether (DPM)); nitriles (e.g., acetonitrile); and formamides (e.g., dimethylformamide). The solvent (e.g., solvent mixture) may be selected so that it is capable of dissolving one or more fluorinated silanes disclosed herein and optionally any hydrolysis catalyst included in the treatment composition.

In some embodiments, the solvent comprises at least one of an alcohol, a ketone, a nitrile, a formamide, or a hydrocarbon. In some of these embodiments, the solvent comprises at least one of methanol, ethanol, propanol, butanol, acetone, acetonitrile, or dimethylformamide. In some embodiments, the solvent comprises at least one of kerosene, diesel, gasoline, pentane, hexane, heptane, mineral oil, or a naphthene. In some embodiments, the solvent is selected such that it has the formula Y-H where Y is the hydrolyzable group of the fluorinated silane. In some embodiments of the methods disclosed herein, the solvent comprises up to 95, 80, 75, 50, 40, 30, 20, or 10 percent by weight of a monohydroxy alcohol having up to 4 carbon atoms, based on the total weight of the treatment composition.

In some embodiments, treatment compositions useful in practicing the present disclosure contain two or more different solvents. In some embodiments, the compositions comprise at least one of a polyol or polyol ether independently having from 2 to 25 (in some embodiments, 2 to 15, 2 to 10, 2 to 9, or even 2 to 8) carbon atoms and at least one of water, a monohydroxy alcohol, an ether, or a ketone, wherein the monohydroxy alcohol, the ether, and the ketone each independently have up to 4 carbon atoms. In some of these embodiments, the polyol or polyol ether is present in the composition at at least 50, 55, 60, or 65 percent by weight and up to 75, 80, 85, or 90 percent by weight, based on the total weight of the composition. The term "polyol" refers to an organic molecule consisting of C, H, and O atoms connected one to another by C-H, C-C, C-O, O-H single bonds, and having at least two C-O-H groups. In some embodiments, useful polyols (e.g., diols or glycols) have 2 to 25, 2 to 20, 2 to 15, 2 to 10,

2 to 8, or even 2 to 6 carbon atoms. In some embodiments, the solvent comprises a polyol ether. The term "polyol ether" refers to an organic molecule consisting of C, H, and O atoms connected one to another by C-H, C-C, C-O, O-H single bonds, and which is at least theoretically derivable by at least partial etherifϊcation of a polyol. In some embodiments, the polyol ether has at least one C-O-H group and at least one C-O-C linkage. Useful polyol ethers (e.g., glycol ethers) may have from 3 to 25 carbon atoms, 3 to 20, 3 to 15, 3 to 10, 3 to 9, 3 to 8, or even from 5 to 8 carbon atoms. In some embodiments, the polyol is at least one of ethylene glycol, propylene glycol, poly(propylene glycol), 1,3-propanediol, or 1,8-octanediol, and the polyol ether is at least one of 2-butoxyethanol, diethylene glycol monomethyl ether, ethylene glycol monobutyl ether, dipropylene glycol monomethyl ether, or l-methoxy-2-propanol. In some embodiments, the polyol and/or polyol ether has a normal boiling point of less than 450 ⁰F

(232 ⁰C), which may be useful, for example, to facilitate removal of the polyol and/or polyol ether from a well after treatment. In these embodiments, in the event that a component of the solvent is a member of two functional classes, it may be used as either class but not both. For example, ethylene glycol methyl ether may be a polyol ether or a monohydroxy alcohol, but not as both simultaneously. In these embodiments, each solvent component may be present as a single component or a mixture of components. Useful combinations of two solvents include 1,3-propanediol (80%)/isopropanol (IPA) (20%), propylene glycol (70%)/IPA (30%), propylene glycol (90%)/IPA (10%), propylene glycol (80%)/IPA (20%), ethylene glycol (50%)/ethanol (50%), ethylene glycol (70%)/ethanol (30%), propylene glycol monobutyl ether (PGBE) (50%)/ethanol (50%),

PGBE (70%)/ethanol (30%), dipropylene glycol monomethyl ether (DPGME) (50%)/ethanol (50%), DPGME (70%)/ethanol (30%), diethylene glycol monomethyl ether (DEGME) (70%)/ethanol (30%), triethylene glycol monomethyl ether (TEGME) (50%)/ethanol (50%), TEGME (70%)/ethanol (30%), 1,8-octanediol (50%)/ethanol (50%), propylene glycol (70%)/tetrahydrofuran (THF) (30%), propylene glycol (70%)/acetone (30%), propylene glycol (70%), methanol (30%), propylene glycol (60%)/IPA (40%), 2- butoxyethanol (80%)/ethanol (20%), 2-butoxyethanol (70%)/ethanol (30%), 2- butoxyethanol (60%)/ethanol (40%), propylene glycol (70%)/ethanol (30%), ethylene glycol (70%)/IPA (30%), and glycerol (70%)/IPA (30%), wherein the exemplary percentages are by weight are based on the total weight of solvent.

In some embodiments of treatment compositions disclosed herein, the solvent comprises a ketone, ether, or ester having from 4 to 10 (e.g., 5 to 10, 6 to 10, 6 to 8, or 6) carbon atoms or a hydrofluoroether or hydrofluorocarbon. In some of these embodiments, the solvent comprises two different ketones, each having 4 to 10 carbon atoms (e.g., any combination of 2-butanone, 4-methyl-2-pentanone, 3-methyl-2-pentanone, 2-methyl-3- pentanone, and 3,3-dimethyl-2-butanone). In some embodiments, the solvent further comprises at least one of water or a monohydroxy alcohol having up to 4 carbon atoms (e.g., methanol, ethanol, n-propanol, isopropanol, 1-butanol, 2-butanol, isobutanol, and t- butanol). Useful ethers having 4 to 10 carbon atoms include diethyl ether, diisopropyl ether, tetrahydrofuran, p-dioxane, and tert-butyl methyl ether. Useful esters having 4 to 10 carbon atoms include ethyl acetate, propyl acetate, and butyl acetate. Useful hydrofluoroethers may be represented by the general formula Rf³-[O-Rh]_a, wherein a is an integer from 1 to 3; Rf³ is a perfluoroalkyl or di- or trivalent perfluoroalkylene, each of which may be interrupted with at least one -O-; and Rh is an alkyl group optionally interrupted with at least one -O-. Numerous hydrofluoroethers of this type are disclosed in U. S. Pat. No. 6,380,149 (Flynn et al.), the disclosure of which is incorporated herein by reference. In some embodiments, the hydrofluoroether is methyl perfluorobutyl ether or ethyl perfluorobutyl ether. Useful hydrofluoroethers also include hydrofluoroethers available, for example, from 3M Company, St. Paul, MN, under the trade designations "HFE-7100" and "HFE-7200".

The amount of solvent typically varies inversely with the amount of other components in compositions according to and/or useful in practicing the present disclosure. For example, based on the total weight of the composition the solvent may be present in the composition in an amount of from at least 50, 60, or 75 percent by weight or more up to 60, 70, 80, 90, 95, 98, or 99 percent by weight, or more.

In some embodiments, the solvent comprises water, for example, in an amount effective to hydrolyze the hydrolyzable groups. In some embodiments, the amount of water will be in a range from 0.1 to 30% by weight of the total treatment composition, in some embodiments up to 15% by weight, up to 10% by weight, or up to 5% by weight. In other embodiments, water is present in an amount of at least 1% by weight, at least 5% by weight, or at least 10% by weight of the total treatment composition. In some embodiments, treatment compositions useful for practicing the present disclosure comprise one of an acidic compound or an alkaline compound strong enough to catalyze hydrolysis of a Si-Y bond. Useful acidic compounds include both organic and inorganic acids. Organic acids include acetic acid, citric acid, formic acid, triflic acid, perfluorobutyric acid, and combinations thereof. Inorganic acids include sulfuric acid, hydrochloric acid, hydroboric acid, phosphoric acid, and combinations thereof. The acid compounds also include acid precursors that form an acid when contacted with water. Combinations of any of these acids may also be useful. Useful alkaline compounds include amines, alkali metal hydroxides, alkaline earth metal hydroxides, and combinations thereof. Exemplary alkaline compounds include sodium hydroxide, potassium hydroxide, sodium fluoride, potassium fluoride, and trimethylamine.

Acidic or alkaline compounds strong enough to catalyze hydrolysis of the Si-Y bond can generally be used in amounts in a range from 0.01 to 10%, but may be used in amount of at least 0.05%, at least 0.1%, at least 1%, or at least 5%, and in amounts up to 8%, up to 5%, up to 1%, or up to 0.1%, by weight based on the total weight of the treatment composition.

The ingredients for treatment compositions described herein including fluorinated silanes, solvents, and optionally water and/or a hydrolysis catalyst can be combined using techniques known in the art for combining these types of materials, including using conventional magnetic stir bars or mechanical mixer (e.g., in-line static mixer and recirculating pump).

In some embodiments, the methods disclosed herein are useful for hydrocarbon- bearing formations having brine. The brine present in the hydrocarbon-bearing formation may be from a variety of sources including at least one of connate water, flowing water, mobile water, immobile water, residual water from a fracturing operation or from other downhole fluids, or crossflow water (e.g., water from adjacent perforated formations or adjacent layers in the formations). The brine may cause water blocking in the hydrocarbon-bearing formation. Salts that may be present in the brine include sodium chloride, calcium chloride, strontium chloride, magnesium chloride, potassium chloride, ferric chloride, ferrous chloride, and hydrates thereof. It is believed that useful treatment compositions will not undergo precipitation of the fluoropolyether silane, dissolved salts, or other solids when the treatment compositions encounter the brine. Such precipitation may inhibit the adsorption or reaction of the fluoropolyether silane on the formation, may clog the pores in the hydrocarbon-bearing formation thereby decreasing the permeability and the hydrocarbon and/or brine production, or a combination thereof.

In some embodiments, methods according to the present disclosure include receiving (e.g., obtaining or measuring) data comprising the temperature and the brine composition (including the brine saturation level and components of the brine) of a selected hydrocarbon-bearing formation. These data can be obtained or measured using techniques well known to one skilled in the art. In some embodiments, the methods comprise selecting a treatment composition for the hydrocarbon-bearing formation comprising the fluoropolyether silane and solvent, based on the behavior of a mixture of the brine composition and the treatment composition. Typically, for the methods disclosed herein, a mixture of an amount of brine and the treatment composition is transparent and substantially free of precipitated solid (e.g., salts, asphaltenes, or fluorinated silanes). Although not wanting to be bound by theory, it is believed the effectiveness of the methods disclosed herein for improving hydrocarbon productivity of a particular oil and/or gas well having brine accumulated in the near wellbore region will typically be determined by the ability of the composition to dissolve or displace the quantity of brine present in the near wellbore region of the well while delivering the polymer to the well. Hence, at a given temperature greater amounts of compositions having lower brine solubility (i.e., compositions that can dissolve a relatively lower amount of brine) will typically be required to treat a hydrocarbon-bearing formation than compositions having higher brine solubility but containing the same fluoropolyether silane at the same concentration.

As used herein, the term transparent refers to allowing clear view of objects beyond. In some embodiments, transparent refers to liquids that are not hazy or cloudy. The term "substantially free of precipitated solid" refers to an amount of precipitated solid that does not interfere with the ability of the fluoropolyether silane to increase the gas or liquid permeability of the hydrocarbon-bearing formation. In some embodiments, "substantially free of precipitated solid" means that no precipitated solid is visually observed. In some embodiments, "substantially free of precipitated solid" is an amount of solid that is less than 5% by weight higher than the solubility product at a given temperature and pressure. In some embodiments, the transparent mixture of the brine composition and the treatment composition separates into at least two separate transparent liquid layers, and in other embodiments, the transparent mixture does not separate into layers. Phase behavior of a mixture of the brine composition and the treatment composition can be evaluated prior to treating the hydrocarbon-bearing formation by obtaining a sample of the brine from the hydrocarbon-bearing formation and/or analyzing the composition of the brine from the hydrocarbon-bearing formation and preparing an equivalent brine having the same or similar composition to the composition of the brine in the formation. The brine composition and the treatment composition can be combined (e.g., in a container) at the temperature and then mixed together (e.g., by shaking or stirring). The mixture is then maintained at the temperature for a certain time period (e.g., 15 minutes), removed from the heat, and immediately visually evaluated to see if phase separation, cloudiness, or precipitation occurs. The amount of the brine composition in the mixture may be in a range from 5 to 95 percent by weight (e.g., at least 10, 20, 30, percent by weight and up to 35, 40, 45, 50, 55, 60, or 70 percent by weight) based on the total weight of the mixture. The phase behavior of the treatment composition and the brine can be evaluated over an extended period of time (e.g., 1 hour, 12 hours, 24 hours, or longer) to determine if any phase separation, precipitation, or cloudiness is observed. By adjusting the relative amounts of brine (e.g., equivalent brine) and the treatment composition, it is possible to determine the maximum brine uptake capacity (above which precipitation occurs) of the treatment composition at a given temperature. Varying the temperature at which the above procedure is carried out typically results in a more complete understanding of the suitability of treatment compositions for a given well.

In addition to using a phase behavior evaluation, it is also contemplated that one may be able to obtain the compatibility information, in whole or in part, by computer simulation or by referring to previously determined, collected, and/or tabulated information (e.g., in a handbook, table, or a computer database). In some embodiments, the selecting a treatment composition comprises consulting a table of compatibility data between brines and treatment compositions at different temperatures.

Whether the mixture of the brine composition and the treatment composition is transparent, substantially free of precipitated solid, and separates into layers at the temperature of the hydrocarbon-bearing formation can depend on many variables (e.g., concentration of the fluoropoly ether silane, solvent composition, brine concentration and composition, hydrocarbon concentration and composition, and the presence of other components (e.g., surfactants or scale inhibitors)). Typically, for treatment compositions comprising at least one of a polyol or polyol ether described above and a monohydroxy alcohol having up to 4 carbon atoms, mixtures of the brine composition and the treatment composition do not separate into two or more layers. In some of these embodiments, the salinity of the brine is less than 150,000 ppm (e.g., less than 140,000, 130,000, 120,000, or 110,000 ppm) total dissolved salts. Typically, for treatment compositions described above comprising at least one (e.g., one or two) ketone having from 4 to 10 carbon atoms or a hydrofluoroether, mixtures of the brine composition and the treatment composition separate into two or more layers. In some of these embodiments, the salinity of the brine is greater than 100,000 ppm (e.g., greater than 110,000, 125,000, 130,000, or 150,000 ppm) total dissolved salt. Although not wishing to be bound by theory, it is believed that when two or more layers form in such mixtures, the fluoropolyether silane preferentially partitions into a layer rich in organic solvent that has a lower concentration of dissolved salts. Typically, treatment compositions comprising at least one of a polyol or polyol ether described above and treatment compositions comprising at least one ketone having from 4 to 10 carbon atoms or a hydrofluoroether are capable of solubilizing more brine (i.e., no salt precipitation occurs) in the presence of a fluorinated silane than methanol, ethanol, propanol, butanol, or acetone alone.

In some embodiments, the treatment composition further comprises a scale inhibitor. Useful scale inhibitors include polyacrylic acid, ethylenediaminetetraacetic acid, hydrochloric acid, formic acid, citric acid, acetic acid, phosphonates, phosphonic acids (e.g., 2-phosphono-,l,2,4-butanetricaboxylic acid, amino(trimethylene) phosphonic acid), diphosphonic acid, and phosphate esters. In some embodiments, the scale inhibitor is polyacrylic acid.

Typically the method disclosed herein modifies the wettability of the hydrocarbon- bearing formation. Wettability modification may help increase well deliverability of oil and/or gas in a hydrocarbon-bearing formation. Wettability can play a role in liquid accumulation around a wellbore. The effect of wettability on condensate accumulation in porous media can be expressed with the Young-Laplace equation: P_c = (2σcosθ)/r where the capillary pressure P_c is proportional to interfacial tension (σ) and the cosine of the pseudocontact angle (cosθ), and is inversely proportional to pore size (r). Thus, according to the Young -Laplace equation, decreasing the cosine of the pseudocontact angle for a given liquid will correspondingly decrease the capillary pressure and thus may increase well deliverability by decreasing, for example, condensate accumulation or water around a wellbore. In some embodiments, modifying the wettability of the hydrocarbon-bearing formation is selected from the group consisting of modifying the gas wetting, modifying the liquid wetting, and modifying a combination thereof. In some embodiments, the gas wetting is increased while the liquid wetting is decreased. Reducing the rate of imbibition of materials such as water, oil, or both, may also improve well deliverability. Typically, the method disclosed herein reduces the rate of imbibition of oil in the hydrocarbon-bearing formation. One convenient proxy for measuring the rate of imbibition of hydrocarbon is the measurement of the rate of imbibition of n-decane on a core sample of the formation. Accordingly, in some embodiments, the method disclosed herein may further comprise reducing the rate of n- decane imbibition of the hydrocarbon-bearing formation. In other embodiments, the method may further comprise reducing the rate of water imbibition of the hydrocarbon- bearing formation. In some embodiments of the treatment methods disclosed herein, the hydrocarbon- bearing formation has both liquid hydrocarbons and gas, and the hydrocarbon-bearing formation has at least a gas permeability that is increased after the hydrocarbon-bearing formation is treated with the treatment composition. In some embodiments, the gas permeability after treating the hydrocarbon-bearing formation with the treatment composition is increased by at least 5 percent (in some embodiments, by at least 10, 15,

20, 30, 40, 50, 60, 70, 80, 90, or 100 percent or more) relative to the gas permeability of the formation before treating the formation with the treatment composition. In some embodiments, the gas permeability is a gas relative permeability. In some embodiments, the liquid (e.g., oil or condensate) permeability in the hydrocarbon-bearing formation is also increased (in some embodiments, by at least 5, 10, 15, 20, 30, 40, 50, 60, 70, 80, 90, or 100 percent or more) after treating the formation with the treatment composition.

To measure the effects of the method disclosed herein, it may be convenient to inject a liquid (e.g., oil, water, or condensate) into a core (e.g., a sandstone core or a limestone core) or a particulate pack (e.g., a sand pack or particulate calcium carbonate). This injection will produce a maximum pressure drop across the sandstone formation. When the wettability of the core, for example, is reduced for the liquid injected into the core, the effectiveness of the treatment may be manifested as a lower measured pressure drop. The pressure drop, if any, can be 5% or more with respect to the pressure across an untreated core, 10% or more, 20% or more, 30% or more, or 50% or more. The maximum pressure drop can be up to 95%, up to 90%, up to 75%, up to 70%, up to 50%, or up to 40%. Permeability can be calculated from the maximum pressure drop. The hydrocarbon-bearing formation that can be treated according to the methods disclosed herein may have both gas and liquid hydrocarbons and may have gas condensate, black oil, or volatile oil. The hydrocarbons may comprise, for example, at least one of methane, ethane, propane, butane, pentane, hexane, heptane, octane, nonane, decane, or higher hydrocarbons. The term "black oil" refers to the class of crude oil typically having gas-oil ratios (GOR) less than about 2000 scf/stb (356 m³/m³). For example, a black oil may have a GOR in a range from about 100 (18), 200 (36), 300 (53), 400 (71), or even 500 scf/stb (89 m³/m³) up to about 1800 (320), 1900 (338), or 2000 scf/stb (356 m³/m³). The term "volatile oil" refers to the class of crude oil typically having a GOR in a range between about 2000 and 3300 scf/stb (356 and 588 m³/m³). For example, a volatile oil may have a GOR in a range from about 2000 (356), 2100 (374), or 2200 scf/stb (392 m³/m³) up to about 3100 (552), 3200 (570), or 3300 scf/stb (588 m³/m³). In some embodiments, the solvent (in the treatment composition) at least partially solubilizes or at least partially displaces the liquid hydrocarbons in the hydrocarbon- bearing formation.

Generally, for the treatment methods disclosed herein, the amounts of the fluoropoly ether silane and solvent (and type of solvent) is dependent on the particular application since conditions typically vary between wells, at different depths of individual wells, and even over time at a given location in an individual well. Advantageously, treatment methods according to the present disclosure can be customized for individual wells and conditions.

The hydrocarbon-bearing formations that may be treated according to the present disclosure may be siliciclastic (e.g., shale, conglomerate, diatomite, sand, and sandstone) or carbonate (e.g., limestone or dolomite) formations. In some embodiments, the hydrocarbon-bearing formation is predominantly sandstone (i.e., at least 50 percent by weight sandstone). In some embodiments, the hydrocarbon-bearing formation is predominantly limestone (i.e., at least 50 percent by weight limestone). The methods disclosed herein are unexpectedly effective at treating both sandstone and limestone hydrocarbon-bearing formations. In previous work, nonionic polymeric fluorinated surfactants have been shown to have limited effectiveness on limestone; (see, e.g.,

Comparative Example A in Int. Pat. Appl. Pub. No. WO 2009/148831 (Sharma et al), the disclosure of which example is incorporated herein by reference). Methods according to the present disclosure may be practiced, for example, in a laboratory environment (e.g., on a core sample (i.e., a portion) of a hydrocarbon-bearing formation or in the field (e.g., on a subterranean hydrocarbon-bearing formation situated downhole). Typically, the methods disclosed herein are applicable to downhole conditions having a pressure in a range from about 1 bar (100 kPa) to about 1000 bars

(100 MPa) and have a temperature in a range from about 100 ⁰F (38 ⁰C) to 400 ⁰F (204 ⁰C) although the methods are not limited to hydrocarbon-bearing formations having these conditions. In some embodiments, the hydrocarbon-bearing formation that is treated has a temperature of up to 200 ⁰F (93 ⁰C), 175 ⁰F (79 ⁰C), 150 ⁰F (66 ⁰C), 125 ⁰F (52 ⁰C), or 100 ⁰F (38 ⁰C). Those skilled in the art, after reviewing the instant disclosure, will recognize that various factors may be taken into account in practice of the any of the disclosed methods including the ionic strength of the brine, pH (e.g., a range from a pH of about 4 to about 10), and the radial stress at the wellbore (e.g., about 1 bar (100 kPa) to about 1000 bars (100 MPa)). In the field, treating a hydrocarbon-bearing formation with a treatment composition described herein can be carried out using methods (e.g., by pumping under pressure) well known to those skilled in the oil and gas art. Coil tubing, for example, may be used to deliver the treatment composition to a particular geological zone of a hydrocarbon-bearing formation. In some embodiments of practicing the methods described herein it may be desirable to isolate a geological zone (e.g., with conventional packers) to be treated with the composition.

Methods described herein are useful, for example on both existing and new wells. Typically, it is believed to be desirable to allow for a shut-in time after treatment compositions described herein contact hydrocarbon-bearing formations. Exemplary shut- in times include a few hours (e.g., 1 to 12 hours), about 24 hours, or even a few (e.g., 2 to

10) days. After the treatment composition has been allowed to remain in place for a selected time, the solvents present in the composition may be recovered from the formation by simply pumping fluids up tubing in a well as is commonly done to produce fluids from a formation. In some embodiments of treatment methods according to the present disclosure, the method comprises treating the hydrocarbon-bearing formation with a fluid prior to treating the hydrocarbon-bearing formation with the treatment composition. In some embodiments, the fluid at least one of at least partially solubilizes or at least partially displaces brine or hydrocarbons in the hydrocarbon-bearing formation. In some embodiments, the fluid at least partially solubilizes brine. In some embodiments, the fluid at least partially displaces brine. In some embodiments, the fluid at least one of at least partially solubilizes or displaces liquid hydrocarbons in the hydrocarbon-bearing formation. In some embodiments, the fluid is substantially free of fluorochemicals. The term "substantially free of fluorochemicals" refers to fluid that may have a fluorochemical in an amount insufficient for the fluid to have a cloud point (e.g., when it is below its critical micelle concentration). A fluid that is substantially free of fluorochemical may be a fluid that has a fluorochemical but in an amount insufficient to alter the wettability of, for example, a hydrocarbon-bearing formation under downhole conditions. A fluid that is substantially free of fluorochemicals includes those that have a weight percent of such fluorochemicals as low as 0 weight percent. The fluid may be useful for decreasing the concentration of at least one of the salts present in a brine prior to introducing the treatment composition to the hydrocarbon-bearing formation. The change in brine composition may change the results of a phase behavior evaluation (e.g., the combination of a treatment composition with a first brine prior to the fluid preflush may result in salt precipitation while the combination of the treatment composition with the brine after the fluid preflush may result in a transparent mixture with no salt precipitation.) In some embodiments of treatment methods disclosed herein, the fluid comprises at least one of toluene, diesel, heptane, octane, or condensate. In some embodiments, the fluid comprises at least one of water, methanol, ethanol, or isopropanol. In some embodiments, the fluid comprises any of the solvents or solvent combinations mentioned above. In some embodiments, the fluid comprises at least one of nitrogen, carbon dioxide, or methane. In some embodiments, the fluid comprises a scale inhibitor (e.g., any of the scale inhibitors described above).

Advantageously, treatment methods disclosed herein typically provide an increase in at least one of the gas permeability, the hydrocarbon liquid permeability, or the water permeability of the formation without fracturing the formation. In the field, for example, manmade fractures are typically made by injecting a fracturing fluid into a subterranean geological formation at a rate and pressure sufficient to open a fracture therein (i.e., exceeding the rock strength). In some embodiments, hydrocarbon-bearing formations that may be treated according to the methods disclosed herein (e.g., limestone or carbonate formations) have natural fractures. Natural fractures may be formed, for example, as part of a network of fractures.

Referring to Fig. 1, an exemplary offshore oil platform is schematically illustrated and generally designated 10. Semi-submersible platform 12 is centered over submerged hydrocarbon-bearing formation 14 located below sea floor 16. Subsea conduit 18 extends from deck 20 of platform 12 to wellhead installation 22 including blowout preventers 24. Platform 12 is shown with hoisting apparatus 26 and derrick 28 for raising and lowering pipe strings such as work string 30. Wellbore 32 extends through the various earth strata including hydrocarbon- bearing formation 14. Casing 34 is cemented within wellbore 32 by cement 36. Work string 30 may include various tools including, for example, sand control screen assembly 38 which is positioned within wellbore 32 adjacent to hydrocarbon-bearing formation 14. Also extending from platform 12 through wellbore 32 is fluid delivery tube 40 having fluid or gas discharge section 42 positioned adjacent to hydrocarbon-bearing formation 14, shown with production zone 48 between packers 44, 46. When it is desired to treat the near-wellbore region of hydrocarbon-bearing formation 14 adjacent to production zone 48, work string 30 and fluid delivery tube 40 are lowered through casing 34 until sand control screen assembly 38 and fluid discharge section 42 are positioned adjacent to the near- wellbore region of hydrocarbon-bearing formation 14 including perforations 50. Thereafter, a composition described herein is pumped down delivery tube 40 to progressively treat the near-wellbore region of hydrocarbon-bearing formation 14.

While the drawing depicts an offshore operation, the skilled artisan will recognize that the methods for treating a production zone of a wellbore are equally well-suited for use in onshore operations. Also, while the drawing depicts a vertical well, the skilled artisan will also recognize that methods according to the present disclosure are equally well-suited for use in deviated wells, inclined wells or horizontal wells.

Selected Embodiments of the Disclosure In a first embodiment, the present disclosure provides a method of treating a hydrocarbon-bearing formation, the method comprising: contacting the hydrocarbon-bearing formation with a treatment composition comprising solvent and a fluoropolyether silane, wherein the fluoropolyether silane is selected from the group consisting of:

(a) Rf -[Q-XHSi(YVY)₃-W)₁J_n;

(b) a compound comprising at least one first divalent unit represented by

Rf-Q-X- O-C=O ; and , at . , least . one or ,

(i) a second divalent unit comprising a pendent -Si(Y')_w(Y)₃__w group; or (ii) a monovalent unit comprising a thioether linkage and at least one terminal -Si(Y')w(Y)_3-w group; and (c) combinations thereof; wherein each Rf is independently a polyfluoropolyether group having a weight average molecular weight of at least 750 grams per mole;

Rf is a monovalent or divalent polyfluoropolyether group having a weight average molecular weight of at least 750 grams per mole; each Q is independently a bond, -C(O)-N(R¹)-, or -C(O)-O-; R and R¹ are each independently hydrogen or alkyl having up to 4 carbon atoms; each X is independently alkylene, arylalkylene, or alkylarylene, wherein alkylene, arylalkylene, and alkylarylene are each optionally interrupted by at least one ether linkage; each X' is independently divalent or trivalent alkylene, arylalkylene, or alkylarylene, wherein alkylene, arylalkylene, and alkylarylene are each optionally interrupted by at least one ester, amide, ether, carbamate, urea, or amine linkage; Y is a hydrolyzable group; Y' is a non-hydrolyzable group; each w is independently 0, 1, or 2; and m and n are each independently 1 or 2, wherein the method does not include intentionally fracturing the hydrocarbon-bearing formation. In a second embodiment, the present disclosure provides the method of embodiment 1 , wherein the fluoropolyether silane is the compound comprising at least one first divalent unit represented by

Rf-Q-X- O-C=O ; and , at . , least . one of , a second divalent unit comprising a pendant -Si(Y')_w(Y)3-w group; or a monovalent unit comprising a thioether linkage and at least one terminal -Si(Y')_w(Y)3__w group.

In a third embodiment, the present disclosure provides the method of embodiment 1 or 2, wherein each second divalent unit is represented by formula:

Y₃__w(Y')_wSi-V-O-C=O wherein each R² is independently selected from the group consisting of hydrogen and alkyl having from 1 to 4 carbon atoms; and each V is independently alkylene that is optionally interrupted by at least one ether linkage or amine linkage.

In a fourth embodiment, the present disclosure provides the method of any one of embodiments 1 to 3, wherein the monovalent unit comprising a thioether linkage and at least one terminal -Si(Y')_w(Y)3__w group is represented by a formula selected from the group consisting of:

-S-C_bH_2bOC(O)NHC_bH_2b-Si(Y)w(Y)3-w; and

-S-C_bH_2b.₁[OC(O)NHC_bH_2b-Si(Y)w(Y)₃.w]2, wherein each b is independently an integer from 1 to 5.

In a fifth embodiment, the present disclosure provides the method of embodiment 1 or 2, wherein each first divalent unit is represented by formula:

Rf-C(O)-N(RO-X - 0-C=O wherein each second divalent unit is represented by a formula:

Y₃__w(Y')_wSi-V-O-C=O and wherein the monovalent unit comprising a thioether linkage and at least one terminal -Si(Y')w(Y)_3-w group is represented by formula:

-S-W-[-Si(Y^>)w(Y)₃-w]m; wherein each R² is independently selected from the group consisting of hydrogen and alkyl having from 1 to 4 carbon atoms; each V is independently alkylene that is optionally interrupted by at least one ether linkage or amine linkage;

W is a divalent or trivalent linking group selected from the group consisting of alkylene, arylalkylene, and arylene, wherein alkylene is optionally interrupted by at least one ether linkage, ester linkage, carbamate, urea, or amide linkage; and m is 1 or 2.

In a sixth embodiment, the present disclosure provides the method of any one of embodiments 1 to 5, wherein the fluoropoly ether silane further comprises at least one divalent unit represented by formula:

RfHC_qH_2q) -o-c=o wherein each Rf¹ is independently a fluoroalkyl group having from 3 to 12 carbon atoms; R⁴ and R⁵ are each independently hydrogen or alkyl having from 1 to

4 carbon atoms; each p is independently an integer having a value from 2 to 11; each q is independently an integer having a value from 1 to 20. In a seventh embodiment, the present disclosure provides the method of any one of embodiments 1 to 6, wherein the fluoropolyether silane further comprises at least one divalent unit represented by formula:

wherein each R² is independently selected from the group consisting of hydrogen and alkyl having from 1 to 4 carbon atoms; and each R³ is independently alkyl having from 1 to 30 carbon atoms. In an eighth embodiment, the present disclosure provides the method of embodiment 1, wherein the fluoropolyether silane is represented by formula: Rf-{C(O)-N(R¹)-X"-[OC(O)-V-Si(Y')_w(Y)₃-_w]_m}_n, or

Rf-{C(O)-N(R¹)-X"-[OC(O)NH-V-Si(Y^>)w(Y)₃.w]m}n, wherein each X" is independently a divalent or trivalent group selected from the group consisting of alkylene, arylalkylene, and alkylarylene, wherein alkylene, arylalkylene, and alkylarylene are each optionally interrupted by at least one ether linkage; and each V is independently alkylene that is optionally interrupted by at least one ether linkage or amine linkage.

In a ninth embodiment, the present disclosure provides the method of embodiment 8, wherein X" is a divalent alkylene group, and wherein m is 1. In a tenth embodiment, the present disclosure provides the method of embodiment

8, wherein X" is a trivalent alkylene group, and wherein m is 2.

In an eleventh embodiment, the present disclosure provides the method of any one of embodiments 1 to 10, wherein Rf and Rf are each independently C₃F₇O(CF(CF₃)CF₂O)_xCF(CF₃)-, C₃F₇O(CF₂CF₂CF₂O)_xCF₂CF₂-, or CF₃O(C₂F₄O)₇CF₂-, wherein x has an average value in a range from 3 to 50, and wherein y has an average value in a range from 6 to 50.

In a twelfth embodiment, the present disclosure provides the method of embodiment 11 , wherein Rf and Rf are each independently

C₃F₇O(CF(CF₃)CF₂O)_xCF(CF₃)-, and wherein x has an average value in a range from 4 to 7.

In a thirteenth embodiment, the present disclosure provides the method of any one of embodiments 1 and 8 to 10, wherein Rf is -CF₂O(CF₂O)_j(C₂F₄O)_kCF₂-, -CF₂O(C₂F₄O)yCF₂-, -CF(CF₃)(OCF₂(CF₃)CF)_xO(CF₂)_z"O(CF(CF₃)CF₂O)_x"CF(CF₃)-, or combinations thereof, wherein j and k each have an average value from 0 to 50 with the proviso that j + k is at least 6, wherein y' has an average value in a range from 6 to 50, wherein x' has an average value in a range from 0 to 50, wherein x" has a value in a range from 3 to 50, and wherein z" has a value in a range from 2 to 20.

In a fourteenth embodiment, the present disclosure provides the method of any one of embodiments 1 to 13, wherein the hydrocarbon-bearing formation comprises at least one of sandstone, shale, conglomerate, diatomite, or sand.

In a fifteenth embodiment, the present disclosure provides the method of any one of embodiments 1 to 14, wherein the hydrocarbon-bearing formation comprises at least one of carbonates or limestone.

In a sixteenth embodiment, the present disclosure provides the method of any one of embodiments 1 to 15, wherein the solvent comprises at least one of water, an alcohol, a glycol, an ether, a glycol ether, a ketone, supercritical carbon dioxide, or a hydrofluoroether. In a seventeenth embodiment, the present disclosure provides the method of embodiment 16, wherein the solvent comprises at least one of methanol, ethanol, propanol, or butanol.

In an eighteenth embodiment, the present disclosure provides the method of embodiment 16 or 17, wherein the solvent comprises at least one of a ketone having from

4 to 10 carbon atoms or a hydrofluoroether.

In a nineteenth embodiment, the present disclosure provides the method of any one of embodiments 1 to 18, further comprising: receiving data comprising a temperature and a brine composition of the hydrocarbon-bearing formation; and selecting the treatment composition for the hydrocarbon-bearing formation comprising the fluoropolyether silane and the solvent, wherein, at the temperature, a mixture of the brine composition and the treatment composition separates into at least two separate transparent liquid layers, and wherein the mixture is free of precipitated solid. In a twentieth embodiment, the present disclosure provides the method of any one of embodiments 1 to 19, wherein the treatment composition further comprises an acidic compound selected from the group consisting of acetic acid, citric acid, formic acid, triflic acid, perfluorobutyric acid, hydroboric acid, sulfuric acid, phosphoric acid, hydrochloric acid, and combinations thereof. In a twenty- first embodiment, the present disclosure provides the method of any one of embodiments 1 to 19, wherein the treatment composition further comprises an alkaline compound selected from the group consisting of an amine, an alkali metal hydroxide, an alkaline earth metal hydroxide, and combinations thereof.

In a twenty-second embodiment, the present disclosure provides the method of any one of embodiments 1 to 21, wherein before contacting the hydrocarbon-bearing formation with the treatment composition, the hydrocarbon-bearing formation has at least one of brine or liquid hydrocarbons, and wherein the hydrocarbon-bearing formation has at least a gas permeability that is increased after it is contacted with the treatment composition. In a twenty-third embodiment, the present disclosure provides the method of embodiment 22, further comprising contacting the hydrocarbon-bearing formation with a fluid before contacting the hydrocarbon-bearing formation with the treatment composition, wherein the fluid at least one of at least partially solubilizes or partially displaces at least one of the brine or liquid hydrocarbons in the hydrocarbon-bearing formation.

In a twenty- fourth embodiment, the present disclosure provides the method of any one of embodiments 1 to 23, wherein the hydrocarbon-bearing formation is penetrated by a wellbore, and wherein a region near the wellbore is contacted with the treatment composition.

In a twenty- fifth embodiment, the present disclosure provides the method of any one of embodiments 1 to 24, wherein the hydrocarbon-bearing formation is at least one of not in contact with proppants or free of manmade fractures. In a twenty-sixth embodiment, the present disclosure provides the method of any one of embodiments 1 to 25, further comprising bonding the hydrocarbon-bearing formation with a fluoropolyether siloxane, wherein the fluoropolyether siloxane comprises at least one condensation product of the fluoropolyether silane.

In a twenty-seventh embodiment, the present disclosure provides the method of embodiment 26, wherein the fluoropolyether siloxane shares at least one siloxane bond with the hydrocarbon-bearing formation.

In a twenty-eighth embodiment, the present disclosure provides a hydrocarbon- bearing formation comprising a surface, wherein at least a portion of the surface is contacted according to the method of any one of embodiments 1 to 27.

Advantages and embodiments of the methods disclosed herein are further illustrated by the following examples, but the particular materials and amounts thereof recited in these examples, as well as other conditions and details, should not be construed to unduly limit this disclosure. Unless otherwise noted, all parts, percentages, ratios, etc. in the examples and the rest of the specification are by weight.

EXAMPLES

In the following Comparative Example A, a nonionic fluorinated polymeric surfactant ("Nonionic Fluorinated Polymeric Surfactant A") was prepared according to the method of U.S. Pat. No. 6,664,354 (Savu), Example 2, Parts A and B, and Example 4, incorporated herein by reference, except using 4270 kilograms (kg) of N- methylperfluorobutanesulfonamidoethanol, 1.6 kg of phenothiazine, 2.7 kg of methoxyhydroquinone, 1590 kg of heptane, 1030 kg of acrylic acid, 89 kg of methanesulfonic acid (instead of triflic acid), and 7590 kg of water in the procedure of Example 2B and using 15.6 grams of 50/50 mineral spirits/TRIGONOX-21-C50 organic peroxide initiator (tert-buty\ peroxy-2-ethylhexanoate obtained from Akzo Nobel, Arnhem, The Netherlands) in place of 2,2'-azobisisobutyronitrile, and with 9.9 grams of 1- methyl-2-pyrrolidinone added to the charges in the procedure of Example 4.

In the following Preparation 1, an oligomeric HFPO methyl ester of the formula F(CF(CF₃)CF₂O)aCF(CF3)C(O)OCH3) was used, wherein "a" averaged about 6.22, with an average molecular weight of 1 ,232 g/mol. The oligomeric HFPO methyl ester was essentially prepared according to the method of U.S. Pat. No. 3,250,808 (Moore), incorporated herein by reference, with purification by fractional distillation.

In the following Preparation 2, an HFPO-succinyl fluoride oligomeric ester (HFPO-SF), more specifically a dimethyl diester of HFPO-SF with an average molecular weight (Mw) of 2,280, CH3θ(O)C(CF3)CF(OCF₂(CF3)CF)_mO(CF₂)4θ(CF(CF3)CF₂O)_nCF(CF₃)C(O)OCH3 was prepared essentially according to the method of U.S. Pat. No. 4,647,413 (Savu), Examples 1-9, incorporated herein by reference.

In the following Preparation 3, an HFPO-diol urethanesilane, CF3CF₂CF₂(CF(CF3)CF₂O)_nCF(CF3)C(O)NHCH₂CH[OC(O)NH(CH₂)₃Si(OC₂H₅)3] CH₂OC(O)NH(CH₂)₃Si(OC₂H₅)₃, with n having a value from 3 to 20 and prepared from the ester with an weight average molecular weight of 1232 grams/mole, was prepared according to the method of published U.S. Patent Application No. 2005/0054804 (Dams), Example 3, incorporated herein by reference.

In the following Preparations 4 and 5, an HFPO-acrylate, F(CF(CF₃)CF₂O)_{6 85}CF(CF₃)C(O)NHCH₂CH₂OC(O)CH=CH₂, was prepared according the method of published US Patent Application No. 2007/0243389 (Audenaert et al), sections (0083) to ( 0085 ) and (0092) to ( 0094) , incorporated herein by reference. In the following Preparation 4, N-Methylperfluorobutanesulfonamidoethyl acrylate (N- MeFBSEA) was prepared according to the method of U.S. Pat. No. 6,664,354 (Savu), Example 2, Parts A and B, the disclosure of which is incorporated herein by reference, except using the modification described above in the procedure of Example 2B. Comparative Preparation A

The "Nonionic Fluorinated Polymeric Surfactant A" was combined as shown in Table 1 , below, wherein the weight percentages were based upon the total weight percentage of the composition. The "Nonionic Fluorinated Polymeric Surfactant A" was added to a flask containing isopropyl alcohol and mixed together using a magnetic stirrer and a magnetic stir bar for 30 minutes. Propylene glycol was then added to the mixture and stirred for 15 minutes.

Table 1

Preparation 1 - Oligomeric HFPO-monosilane

In a three-necked flask of 250 ml fitted with a stirrer, thermometer, cooler and heating mantle, were placed 123.2 g (0.1 mol) of the oligomeric HFPO methyl ester and 22.1 g (0.1 mol) of 3-aminopropyltriethoxysilane (APTES), available from Aldrich, Bornem, Belgium. The mixture was stirred at 40⁰C under nitrogen atmosphere for 2 hours. Infrared (IR) analysis for conversion of ester groups indicated that some un-reacted ester groups were still present. Additional 2.2 g (0.01 mol) of APTES were then added and the reaction continued for 2 hours at 40⁰C. At that time no more residual ester could be detected by IR. Methanol was stripped out at 40⁰C and reduced pressure. NMR-analysis confirmed the chemical structure. The oligomeric HFPO-monosilane was combined with ethanol and a hydrofluoroether (HFE) solvent, available from 3M Company, Minnesota, USA, under the trade designation "NOVEC ENGINEERED FLUID HFE-7200", as shown in Table 2 below, wherein the weight percentages were based upon the total weight percentage of the composition. The oligomeric HFPO-monosilane was added to a flask containing ethanol and mixed together using a magnetic stirrer and a magnetic stir bar for 30 minutes. The

HFE was then added to the mixture and stirred for 15 minutes. Table 2

Preparation 2 - Oligomeric HFPO-disilane

An oligomeric HFPO-disilane was prepared as described in Preparation 1 , except that the oligomeric HFPO methyl ester was replaced with 228g (0.1 mol) of the dimethyl ester of HFPO-SF. The dimethyl ester was reacted with 44.2g (0.2 mol) of APTES. After carrying out the reaction at 4O⁰C under nitrogen for 2 hours, a 12% excess of APTES was added to complete the reaction.

The oligomeric HFPO-disilane was combined with ethanol and hydrofluoroether solvent "NOVEC ENGINEERED FLUID HFE-7200", as shown in Table 3 below, wherein the weight percentages were based upon the total weight percentage of the composition. The oligomeric HFPO-disilane was added to a flask containing ethanol and mixed together using a magnetic stirrer and a magnetic stir bar for 30 minutes. The HFE solvent was then added to the mixture and stirred for 15 minutes.

Table 3

Preparation 3 - HFPO-diol urethanesilane

The HFPO-diol urethanesilane was combined with ethanol and hydrofluoroether solvent "NOVEC ENGINEERED FLUID HFE-7200", as shown in Table 4 below, wherein the weight percentages were based upon the total weight percentage of the composition. The HFPO-diol urethanesilane was added to a flask containing ethanol and mixed together using a magnetic stirrer and a magnetic stir bar for 30 minutes. The HFE solvent was then added to the mixture and stirred for 15 minutes.

Table 4

Preparation 4

To a 500-mL, three-necked flask, fitted with a condenser, stirrer, and thermometer, were added 40.6 grams (0.03 moles) HFPO-acrylate, 61.6 grams (015 moles) MeFBSEA, 23.3 grams (0.069 moles) octadecylmethacrylate (ODMA), 7.4 grams ( 0.03 moles) of 3- trimethoxysilylpropylmethacrylate, 5.9 grams (0.03 moles) of 3- mercaptopropyltrimethoxysilane, 100 grams ethyl acetate and 35 grams of hydrofiuoroether solvent " NOVEC ENGINEERED FLUID HFE-7200" and 0.3 gram AIBN. The mixture was degassed three times using aspirator vacuum and nitrogen pressure. The mixture was reacted under a nitrogen atmosphere at 75 ⁰C for 6 hours. An additional 0.1 gram AIBN was added and the reaction was continued overnight. A clear solution of copolymer HFPO-acrylate/ MeFBSEA/ODMA/3- trimethoxysilylpropylmethacrylate/3-mercaptopropyltrimethoxysilane at a ratio of 1/5/2.3/1/1 was obtained. A 2% solution of the copolymer in a 75/25 mixture of ethanol and hydrofluoroether " NOVEC ENGINEERED FLUID HFE-7200" was prepared.

Preparation 5

To a 500-mL, three-necked flask, fitted with a condenser, stirrer, and thermometer, were added 54.1 grams (0.04 moles) HFPO-acrylate, 6.7 grams (0.02 moles) ODMA, 2.5 grams (0.01 moles) of 3- trimethoxysilylpropylmethacrylate, 2.0 grams (0.01 moles) of 3- mercaptopropyltrimethoxysilane, 30 grams ethyl acetate, 40 grams hydrofluoroether solvent " NOVEC ENGINEERED FLUID HFE-7200", and 0.1 gram AIBN. The mixture was degassed three times using aspirator vacuum and nitrogen pressure. The mixture was reacted under a nitrogen atmosphere at 75 ⁰C for 6 hours. An additional 0.05 gram AIBN was added and the reaction was continued overnight. A clear solution of the copolymer, HFPO-acrylate/ 0DMA/3- trimethoxysilylpropylmethacrylate/3- mercaptopropyltrimethoxysilane in a ration of 4/2/1/1, was obtained. A 2% solution of the copolymer in a 75/25 mixture of ethanol and hydrofluoroether " NOVEC ENGINEERED FLUID HFE-7200" was prepared.

Flow set up and procedure for Example 1.

A schematic diagram of a flow apparatus 100 used to determine relative permeability of sea sand or particulate calcium carbonate is shown in Fig. 2. Flow apparatus 100 included positive displacement pump 102 (Model Gamma/4-W 2001 PP, obtained from Prolingent AG, Regensdorf, Germany). Nitrogen gas was injected at constant rate through a gas flow controller 120 (Model DK37/MSE, Krohne, Duisburg, Germany). Pressure indicators 113, obtained from Siemens under the trade designation "SITRANS P" 0-16 bar, were used to measure the pressure drop across a calcium carbonate pack in vertical core holder 109 (20 cm by 12.5 cm²) (obtained from 3M Company, Antwerp, Belgium). A back-pressure regulator (Model No. BS(H)2; obtained from RHPS, The Netherlands) 104 was used to control the flowing pressure upstream and downstream of core holder 109. Core holder 109 was heated by circulating silicone oil, heated by a heating bath obtained from Lauda, Switzerland, Model R22.

The core holder was filled with particulate calcium carbonate (obtained from Merck, Darmstadt, Germany as granular marble, 0.5 to 2 mm in size) and then heated to 75 ⁰C. A pressure of about 5 bar (5 x 10⁵ Pa) was applied, and the back pressure was regulated in such a way that the flow of nitrogen gas through the particulate calcium carbonate was about 500 to 1000 mL/minute. The initial gas permeability was calculated using Darcy's law.

Synthetic brine according to the natural composition of North Sea brine (containing 5.9% NaCl, 1.6% CaCl₂, 0.23% MgCl₂, and 0.05% KCl) was introduced into the core holder at about 1 mL/minute using displacement pump 102. The treatment composition (Preparation 1) was then injected into the core at a flow rate of 1 mL/minute. The gas permeability after treatment was calculated from the steady state pressure drop, and improvement factor was calculated as the permeability after treatment/permeability before treatment.

After the treatment, brine was injected into the core at about 1 mL/minute using displacement pump 102.

For treatment with the treatment composition of Example 1, the fluid, initial pressure (bar), the pressure change (ΔP), the flow rate for each injection, the amount of fluid used for each injection, the flow rate of gas through the core (Q), the gas permeability (K), and the improvement factor (PI) are shown in Table 5, below. Table 5

Flow set up and procedure for Comparative Example A and Examples 2-4.

The flow setup and procedure described for Example 1 were used, except that the calcium carbonate pack was subjected to heptane injections at about 0.5 mL/minute prior to and after the treatment with the treatment composition. Comparative Preparation A was used for Comparative Example A. Preparations 1, 2, and 3 were used for Examples 2, 3, and 4, respectively.

For treatment with the Comparative Preparation A, and Preparations 1-3, the fluid, initial pressure (bar), the pressure change (ΔP), the flow rate for each injection, the amount of fluid used for each injection, the flow rate of gas through the core (Q), the gas permeability (K), and the improvement factor (PI) are shown in Table 6, below.

Table 6

Flow set up and procedure for Examples 5 and 6.

The flow setup and procedure described for Example 1 were used, except that the core holder was filled with sea sand (grade 10 -20). Preparations 1 and 2 were used for Examples 5 and 6, respectively. For treatment with Preparations 1 and 2, the fluid, initial pressure (bar), the pressure change (ΔP), the flow rate for each injection, the amount of fluid used for each injection, the flow rate of gas through the core (Q), the gas permeability (K), and the improvement factor (PI) are shown in Table 7, below.

Table 7

Flow set up and procedure for Comparative Example B and Examples 7-9.

The flow setup and procedure described for Examples 5 and 6 were used, except that the sea sand pack was subjected to heptane injections at about 0.5 mL/minute prior to and after the treatment with the treatment composition. Comparative Preparation A was used for Comparative Example B, and Preparations 1, 2, and 3 were used for Examples 7,

8, and 9, respectively.

For treatment with Comparative Preparation A and Preparations 1-3, the fluid, initial pressure (bar), the pressure change (ΔP), the flow rate for each injection, the amount of fluid used for each injection, the flow rate of gas through the core (Q), the gas permeability (K), and the improvement factor (PI) are shown in Table 8, below Table 8

Examples 10 and 11

Examples 10 and 11 were carried out according to the method of Examples 7 to 9, with the exception that Preparation 4 and Preparation 5, respectively, were used. For Examples 10 and 11, the fluid, initial pressure (bar), the pressure change (ΔP), the flow rate for each injection, the amount of fluid used for each injection, the flow rate of gas through the core (Q), the gas permeability (K), and the improvement factor (PI) are shown in Table 9, below.

Table 9

The results of the evaluations using sea sand or particulate calcium carbonate can be verified using core flood evaluations either on sandstone or limestone. A schematic diagram of a core flood apparatus 200 that can be used is shown in Fig. 3. Core flood apparatus 200 includes positive displacement pump 202 (Model QX6000SS, obtained from Chandler Engineering, Tulsa, OK) to inject n-heptane at constant rate into fluid accumulator 216. Nitrogen gas can be injected at constant rate through a gas flow controller 220 (Model 5850 Mass Flow Controller, Brokks Instrument, Hatfield, PA). A pressure port 211 on high-pressure core holder 208 (Hassler-type Model RCHR-1.0 obtained from Temco, Inc., Tulsa, OK) can be used to measure pressure drop across the vertical core 209. A back-pressure regulator (Model No. BP-50; obtained from Temco, Tulsa, OK) 204 can be used to control the flowing pressure downstream of core 209. High-pressure core holder 208 can be heated with 3 heating bands 222 (Watlow Thinband Model STB4A2AFR-2, St. Louis, MO). In a typical procedure, a core can be dried for 72 hours in a standard laboratory oven at 95 ⁰C and then wrapped in aluminum foil and heat shrink tubing. Referring again to Fig. 3, the wrapped core 209 can placed in core holder 208 at the desired temperature. An overburden pressure of, for example, 2300 psig (1.6 x 10⁷ Pa) can be applied. The initial single-phase gas permeability can be measured using nitrogen at low system pressures between 5 to 10 psig (3.4 x 10⁴ to 6.9 x 10⁴ Pa).

Deionized water or brine can be introduced into the core 209 by the following procedure to establish the desired water saturation. The outlet end of the core holder is connected to a vacuum pump and a full vacuum can be applied for 30 minutes with the inlet closed. The inlet can be connected to a burette with the water in it. The outlet is closed and the inlet is opened to allow the desired amount of water to flow into the core. The inlet and the outlet valves can then be closed for the desired time. The gas permeability can be measured at the water saturation by flowing nitrogen at 500 psig (3.4 x 10⁶ Pa). The core holder 208 can then be heated to a higher temperature, if desired, for several hours. Nitrogen and n-heptane can be co-injected into the core at an average total flow rate in the core of, for example, 450 mL/hour at a system pressure of, for example, 900 psig (6.2 x 10⁶ Pa) until steady state is reached. The flow rate of nitrogen is controlled by gas flow controller 220, and the rate for n-heptane is controlled by positive displacement pump 202. The flow rates of nitrogen and n-heptane can be set such that the fractional flow of gas in the core was 0.66. The gas relative permeability before treatment can then be calculated from the steady state pressure drop. The treatment composition can then be injected into the core at a flow rate of, for example, 120 mL/hour for about 20 pore volumes. Nitrogen and n-heptane co-injection can be resumed at an average total flow rate in the core of, for example, 450 mL/hour at a system pressure of, for example, 900 psig (6.2 x 10⁶ Pa) until steady state is reached. The gas relative permeability after treatment can then be calculated from the steady state pressure drop.

Various modifications and alterations of this disclosure may be made by those skilled the art without departing from the scope and spirit of the disclosure, and it should be understood that this disclosure is not to be unduly limited to the illustrative embodiments set forth herein.

Claims

What is claimed is:

1. A method of treating a hydrocarbon-bearing formation, the method comprising: contacting the hydrocarbon-bearing formation with a treatment composition comprising solvent and a fluoropolyether silane, wherein the fluoropolyether silane is selected from the group consisting of:

(a) Rf -[Q-X'-(Si(Y^>)w(Y)3-w)m]n;

(b) a compound comprising at least one first divalent unit represented by

Rf-Q-X- O-C=O ; an ^d a₊t ₁ leas₊t one o rf (i) a second divalent unit comprising a pendent -Si(Y')_w(Y)₃__w group; or (ii) a monovalent unit comprising a thioether linkage and at least one terminal -Si(Y')w(Y)_3-w group; and (c) combinations thereof; wherein each Rf is independently a polyfluoropolyether group having a weight average molecular weight of at least 750 grams per mole;

Rf is a monovalent or divalent polyfluoropolyether group having a weight average molecular weight of at least 750 grams per mole; each Q is independently a bond, -C(O)-N(R¹)-, or -C(O)-O-; R and R¹ are each independently hydrogen or alkyl having up to 4 carbon atoms; each X is independently alkylene, arylalkylene, or alkylarylene, wherein alkylene, arylalkylene, and alkylarylene are each optionally interrupted by at least one ether linkage; each X' is independently divalent or trivalent alkylene, arylalkylene, or alkylarylene, wherein alkylene, arylalkylene, and alkylarylene are each optionally interrupted by at least one ester, amide, ether, carbamate, urea, or amine linkage;

Y is a hydrolyzable group; Y' is a non-hydrolyzable group; each w is independently 0, 1, or 2; and m and n are each independently 1 or 2, wherein the method does not include intentionally fracturing the hydrocarbon-bearing formation.

2. The method according to claim 1, wherein the fluoropoly ether silane is the compound comprising at least one first divalent unit represented by

Rf-Q-X- O-C=O ; and , at . , least . one or , a second divalent unit comprising a pendant -Si(Y')_w(Y)_3-w group; or a monovalent unit comprising a thioether linkage and at least one terminal -Si(Y')_w(Y)3__w group.

3. The method according to claim 1 or 2, wherein each first divalent unit is represented by formula:

wherein each second divalent unit is represented by a formula:

Y₃__w(Y')_wSi-V-0-C=0 and wherein the monovalent unit comprising a thioether linkage and at least one terminal -Si(Y')w(Y)_3-w group is represented by formula:

-S-W-[-Si(Y)w(Y)₃-w]m; wherein each R is independently selected from the group consisting of hydrogen and alkyl having from 1 to 4 carbon atoms; each V is independently alkylene that is optionally interrupted by at least one ether linkage or amine linkage;

4. The method according to claim 1 or 2, wherein the fluoropolyether silane further comprises at least one divalent unit represented by formula:

wherein each Rf¹ is independently a fluoroalkyl group having from 3 to 12 carbon atoms; R⁴ and R⁵ are each independently hydrogen or alkyl having from 1 to

4 carbon atoms; each p is independently an integer having a value from 2 to 11; each q is independently an integer having a value from 1 to 20.

5. The method according to claim 1 or 2, wherein the fluoropolyether silane further comprises at least one divalent unit represented by formula:

wherein each R² is independently selected from the group consisting of hydrogen and alkyl having from 1 to 4 carbon atoms; and each R is independently alkyl having from 1 to 30 carbon atoms.

6. A method according to claim 1, wherein the fluoropoly ether silane is represented by formula:

Rf-{C(O)-N(R¹)-X"-[OC(O)-V-Si(Y^>)_w(Y)₃-_w]_m}_n, or Rf-{C(O)-N(R¹)-X"-[OC(O)NH-V-Si(Y^>)w(Y)₃.w]m}n, wherein each X" is independently a divalent or trivalent group selected from the group consisting of alkylene, arylalkylene, and alkylarylene, wherein alkylene, arylalkylene, and alkylarylene are each optionally interrupted by at least one ether linkage; and each V is independently alkylene that is optionally interrupted by at least one ether linkage or amine linkage.

7. The method according to claim 6, wherein X" is a trivalent alkylene group, and wherein m is 2.

8. The method according to any one of claims 1 to 7, wherein Rf and Rf are each independently C₃F₇O(CF(CF₃)CF₂O)_xCF(CF₃)-, C₃F₇O(CF₂CF₂CF₂O)_xCF₂CF₂-, or CF₃O(C₂F₄θ)_yCF₂-, wherein x has an average value in a range from 3 to 50, and wherein y has an average value in a range from 6 to 50.

9. The method according to any one of claims 1, 6, or 7, wherein Rf is -CF₂O(CF₂O)_J(C₂F₄O)₁^CF₂-, -CF₂O(C₂F₄OVCF₂-, -CF(CF₃)(OCF₂(CF₃)CF)_XO(CF₂)Z-O(CF(CF₃)CF₂O)_X-CF(CF₃)-, or combinations thereof, wherein j and k each have an average value from 0 to 50 with the proviso that j + k is at least 6, wherein y' has an average value in a range from 6 to 50, wherein x' has an average value in a range from 0 to 50, wherein x" has a value in a range from 3 to 50, and wherein z" has a value in a range from 2 to 20.

10. The method according to any preceding claim, wherein the solvent comprises at least one of water, an alcohol, a glycol, an ether, a glycol ether, a ketone, supercritical carbon dioxide, or a hydrofluoroether.

11. The method according to claim 10, wherein the solvent comprises at least one of a ketone having from 4 to 10 carbon atoms or a hydrofluoroether.

12. The method according to any preceding claim, further comprising: receiving data comprising a temperature and a brine composition of the hydrocarbon-bearing formation; and selecting the treatment composition for the hydrocarbon-bearing formation comprising the fluoropolyether silane and the solvent, wherein, at the temperature, a mixture of the brine composition and the treatment composition separates into at least two separate transparent liquid layers, and wherein the mixture is free of precipitated solid.

13. The method of any preceding claim, wherein the treatment composition further comprises an acidic compound selected from the group consisting of acetic acid, citric acid, formic acid, triflic acid, perfluorobutyric acid, hydroboric acid, sulfuric acid, phosphoric acid, hydrochloric acid, and combinations thereof, or wherein the treatment composition further comprises an alkaline compound selected from the group consisting of an amine, an alkali metal hydroxide, an alkaline earth metal hydroxide, and combinations thereof.

14. The method according to any preceding claim, wherein before contacting the hydrocarbon-bearing formation with the treatment composition, the hydrocarbon-bearing formation has at least one of brine or liquid hydrocarbons, and wherein the hydrocarbon- bearing formation has at least a gas permeability that is increased after it is contacted with the treatment composition.

15. A hydrocarbon-bearing formation comprising a surface, wherein at least a portion of the surface is contacted according to the method of any preceding claim.