Background

In the oil and gas industry, certain surfactants (including certain fluorinated surfactants) are known as fluid additives for various downhole operations (e.g., fracturing, waterflooding, and drilling). Often, these surfactants function to decrease the surface tension of the fluid or to stabilize foamed fluids.

Some hydrocarbon and fluorochemical compounds have been used to modify the wettability of reservoir rock, which may be useful, for example, to prevent or remediate 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.

Solvent injection (e.g., injection of methanol) has been used to alleviate the problems of water blocking and condensate banking in gas wells, for example, by removing condensate and water banks around a wellbore. This method may provide only a temporary benefit and may not be desirable under some downhole conditions. Furthermore, the low flash point of some solvents presents a fire and explosion hazard.

U.S. Pat. No. 7,585,817 (Pope et al.) reports compositions and methods for improving the productivity of hydrocarbon-producing wells, for example, using a fluorinated polymer and a combination of solvents that can at least one of solubilize or displace brine and/or condensate in the hydrocarbon-bearing formation. U.S. Pat. App. Pub. No. 2015/0315455 (Sayed et al.) discloses a chemical treatment composition for enhancing productivity from a hydrocarbon reservoir. The chemical treatment composition has a flash point of at least 40 °C and includes a solvent mixture and a wettability alteration chemical.

Summary

The present disclosure provides, for example, a composition that includes a fluorinated polymer, a first solvent, and a second solvent and a method of treating a hydrocarbon-bearing formation with the composition. Compositions and methods of the present disclosure may be useful, for example, for increasing the permeability in hydrocarbon-bearing formations wherein two phases (i.e., a gas phase and an oil phase) of the hydrocarbons are present, (e.g., in gas wells having retrograde condensate and oil wells having black oil or volatile oil). The methods are also useful for increasing the permeability in hydrocarbon-bearing formations having brine (e.g., connate brine and/or water blocking). Treatment of a near wellbore region of an oil and/or gas well that has at least one of brine or two phases of hydrocarbons in the near wellbore region using the methods disclosed herein may increase the productivity of the well. Although not wanting to be bound by theory, it is believed that the effectiveness of the compositions and 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 treatment composition to dissolve or displace the quantity of brine present in the near wellbore region of the well without causing precipitation of the fluorinated polymer or salts. Unexpectedly, the combination of the first and second solvent typically can solubilize more brine than comparative combinations of relatively high-flash-point solvents.

In one aspect, the present disclosure provides a composition that includes a fluorinated polymer, a first solvent, and a second solvent. The fluorinated polymer has first divalent units represented by formula X:

and second divalent units, each of which comprises a poly(alkyleneoxy) group. In formula X, Rf represents a fluoroalkyl group having from 1 to 8 carbon atoms or a polyfluoropolyether group, each R ¹ is independently hydrogen or methyl, Q is a bond, -C(0)-N(R)-, or -S0 ₂ -N(R)-, wherein R is alkyl having from 1 to 4 carbon atoms, and m is an integer from 1 to 11. The fluorinated polymer may include more than one type of first divalent unit and/or second divalent unit. The first solvent is ethylene glycol, 1,2- propanediol, or 2,3-butanediol, and the second solvent is a linear monohydroxy alcohol having from 4 to 12 carbon atoms and optionally at least one ether linkage.

In another aspect, the present disclosure provides a method of treating a hydrocarbon-bearing formation. The method includes contacting the hydrocarbon-bearing formation with the above composition.

In another aspect, the present disclosure provides a hydrocarbon-bearing formation having a surface, and at least a portion of the surface is contacted according to the method disclosed herein.

In some embodiments of the foregoing aspects, the hydrocarbon-bearing formation is penetrated by a wellbore, wherein a region near 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 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 or 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, or greater than 50,000 ppm). The unit ppm is equivalent to milligrams per liter (mg/L).

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 "contacting" includes placing a treatment 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 treatment composition into a well, wellbore, or hydrocarbon bearing formation).

The term "solvent" refers to a homogeneous liquid material (inclusive of any water with which it may be combined) that is capable of at least partially dissolving the fluorinated polymer disclosed herein at 25 °C.

"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.

The phrase "interrupted by at least one functional group", for example, with regard to an alkyl (which may or may not be fluorinated), alkylene, or arylalkylene refers to having part of the alkyl, alkylene, or arylalkylene on both sides of the functional group.

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.

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. In some embodiments, 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 region near the wellbore (i.e., near wellbore region) includes a region within about 25 feet (in some embodiments, 20, 15, or 10 feet) of the wellbore.

All numerical ranges are inclusive of their endpoints and nonintegral 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 a core flood set-up that can be useful for evaluating the method disclosed herein in a laboratory; and

Fig. 2 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.

Detailed Description

In the compositions and methods of the present disclosure, the fluorinated polymer comprises (e.g., at least 2, 3, 4, 5, 6, 7, 8, 9, 10, 15, or at least 20 up to 30, 35, 40, 45, 50, 100, or up to 200) first divalent units independently represented by formula:

X

For divalent units having this formula, Q is a bond, -C(0)-N(R)-, or -S0 ₂ N(R)-, wherein R is alkyl having

1 to 4 carbon atoms (e.g., methyl, ethyl, n-propyl, isopropyl, n-butyl, or isobutyl). In some embodiments, Q is a bond. In some embodiments, Q is -S0 ₂ N(R)-. In some embodiments, Q is

-C(0)N(R)-. In some of these embodiments, R is methyl or ethyl m is an integer from 1 to 11 (i.e., 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, or 11). In some of these embodiments, m is 1; in other of these embodiments, m is 2. In some embodiments in which Q is -C(0)N(R)- or -S0 ₂ N(R)-, m is an integer from 2 to 11, 2 to 6, or

2 to 4. In some embodiments wherein Q is a bond, m is an integer from 1 to 6, 1 to 4, or 1 to 2. In embodiments wherein Q is a bond, it should be understood that the first divalent units may also be represented by formula:

XIa

In some embodiments, fluorinated polymers useful for practicing the present disclosure comprise (e.g., at least 2, 3, 4, 5, 6, 7, 8, 9, 10, 15, or at least 20 up to 30, 35, 40, 45, 50, 100, or up to 200) first divalent units independently represented by formula:

Xlb

For divalent units of this formula, n is an integer from 2 to 11 (i.e., 2, 3, 4, 5, 6, 7, 8, 9, 10, or 11). In some embodiments, n is an integer from 2 to 6 or 2 to 4. R is alkyl having 1 to 4 carbon atoms (e.g., methyl, ethyl, n-propyl, isopropyl, n-butyl, or isobutyl). In some embodiments, R is methyl or ethyl.

For any of the embodiments of the first divalent units having Rf groups, each Rf independently represents a fluorinated alkyl group having from 1 to 8 (in some embodiments, 1 to 6, 2 to 6 or 2 to 4) carbon atoms (e.g., trifluoromethyl, perfluoroethyl, 1,1,2,2-tetrafluoroethyl, 2-chlorotetrafluoroethyl, perfluoro-n-propyl, perfluoroisopropyl, perfluoro-n-butyl, 1,1,2,3,3,3-hexafluoropropyl,

perfluoroisobutyl, perfluoro-svobutyl. or perfluoro-fert-butyl, perfluoro-n-pentyl, pefluoroisopentyl, or perfluorohexyl). In some embodiments, Rf is perfluorobutyl (e.g., perfluoro-n-butyl, perfluoroisobutyl, or pc rfl uo ro - sv ob uty 1 ) . In some embodiments, Rf is perfluoropropyl (e.g., perfluoro-n-propyl or perfluoroisopropyl). Rf may contain a mixture of fluoroalkyl groups (e.g., with an average of up to 8, 6, or 4 carbon atoms).

For any of the embodiments of the first divalent units having Rf ² groups, each Rf ² independently represents a fluorinated alkyl group having from 1 to 8 (in some embodiments, 1 to 8, 1 to 6, or 2 to 4) carbon atoms (e.g., trifluoromethyl, perfluoroethyl, 1,1,2,2-tetrafluoroethyl, 2-chlorotetrafluoroethyl, perfluoro-n-propyl, perfluoroisopropyl, perfluoro-n-butyl, 1,1,2,3,3,3-hexafluoropropyl,

perfluoroisobutyl, perfluoro-svobutyl. or perfluoro-fert-butyl, perfluoro-n-pentyl, pefluoroisopentyl, perfluorohexyl, perfluoroheptyl, or perfluorooctyl). In some embodiments, Rf ² is perfluorobutyl (e.g., perfluoro-n-butyl, perfluoroisobutyl, or perfluoro-svc-butyl). In some embodiments, Rf ² is perfluoropropyl (e.g., perfluoro-n-propyl or perfluoroisopropyl). Rf ² may contain a mixture of fluoroalkyl groups (e.g., with an average of up to 8, 6, or 4 carbon atoms).

In some embodiments of fluorinated polymers useful for practicing the present disclosure, the first divalent units have up to 6 fluorinated carbon atoms.

In some embodiments, Rf or Rf ² is a polyfluoropolyether group. The term "polyfluoropolyether" refers to a compound or group having at least 3 (in some embodiments, at least 4, 5, 6, 7, 8, 9, 10, 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 or Rf ² 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 _d F _2d )-, -(C _d Fi _d O)-, -(CF(F'))-, -(CF(F')O)-, -(CF(F')C _d F _2d O)-, -(C _d F _2d CF(F')0)-, ₀ r -(CF ₂ CF(F')0)-. 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 F ¹ 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 F ¹ 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 F ¹ group can have up to 4 (in some embodiments, up to 3, 2, or 1) oxygen atoms; in some embodiments F ¹ has no oxygen atoms. In these perfluoropolyether structures, different repeating units can be combined in a block or random arrangement to form the Rf or Rf ² group. Rf or Rf ² may be a mixture of polyfluoropolyether groups.

In some embodiments, Rf or Rf ² is represented by formula R _f ^a -0-(R _f ^b -0-) _z (R _f ^c )-, wherein R/ ¹ 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 _f ^c is a

perfluoroalkylene having 1 to 6 (in some embodiments, 1 to 4 or 2 to 4) carbon atoms; and z ¹ is in a range 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 _f ^a groups include CF ₃ -, CF ₃ CF ₂ -, CF ₃ CF ₂ CF ₂ -, CF ₃ CF(CF ₃ )-, CF ₃ CF(CF ₃ )CF ₂ -,

CF ₃ CF ₂ CF ₂ CF ₂ -, CF ₃ CF ₂ CF(CF ₃ )-, CF ₃ CF ₂ CF(CF ₃ )CF ₂ -, and CF ₃ CF(CF ₃ )CF ₂ CF ₂ -. In some

embodiments, R _f ^a is CF ₃ CF ₂ CF ₂ -. Representative R ^b groups include -CF ₂ -, -CF(CF ₃ )-, -CF ₂ CF ₂ -, -CF(CF ₃ )CF ₂ -, -CF ₂ CF ₂ CF ₂ -, -CF(CF ₃ )CF ₂ CF ₂ -, -CF ₂ CF ₂ CF ₂ CF ₂ -, and -CF ₂ C(CF ₃ ) ₂ -. Representative R _f ^c groups include -CF ₂ -, -CF(CF ₃ )-, -CF ₂ CF ₂ -, -CF ₂ CF ₂ CF ₂ -, and -CF(CF ₃ )CF ₂ -. In some embodiments, R _f ^c is -CF(CF ₃ )-. In some embodiments, (R _f ^b -0-) _Z' is represented by -[CF ₂ 0]i[CF ₂ CF ₂ 0] _j -,

-[CF ₂ 0] ₁ [CF(CF ₃ )CF ₂ 0] _j -, -[CF ₂ 0]i[CF ₂ CF ₂ CF ₂ 0]j- -[CF ₂ CF ₂ 0]i[CF ₂ 0]j-, -[CF ₂ CF ₂ 0] ₁ [CF(CF ₃ )CF ₂ 0] _J -, -[CFzCFzOl^CFzCFzCFzOl·-, -[CF ₂ CF ₂ CF ₂ 0] ₁ [CF ₂ CF(CF ₃ )0] _J -, and [CF ₂ CF ₂ CF ₂ 0] ₁ [CF(CF ₃ )CF ₂ 0] _J -, wherein i + j is an integer of at least 3 (in some embodiments, at least 4, 5, or 6).

In some embodiments, Rf or Rf ² is selected from the group consisting of

C ₃ F ₇ 0(CF(CF ₃ )CF ₂ 0) _X CF(CF ₃ )-, C ₃ F ₇ 0(CF ₂ CF ₂ CF ₂ 0) _X CF ₂ CF ₂ -, or CF ₃ 0(C ₂ F ₄ 0) _y CF ₂ -, 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 C ₃ F ₇ 0(CF(CF ₃ )CF ₂ 0) _X CF(CF ₃ )-, wherein x has an average value in a range from 4 to 7. In some embodiments, Rf is selected from the group consisting of CF ₃ 0(CF ₂ 0) _x' (C ₂ F ₄ 0) _y' CF ₂ - and F(CF ₂ ) ₃ -0-(C ₄ F ₈ 0) _z" (CF ₂ ) ₃ -, wherein x ¹ , y ¹ , 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 some embodiments wherein Rf or Rf ² is a polyfluoropolyether, Rf or Rf ² 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 or Rf ² has a weight average molecular weight of up to 6000 (in some

embodiments, 5000 or even 4000) grams per mole. In some embodiments, Rf or Rf ² has a weight average molecular weight in a range from 750 grams per mole to 5000 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.

In some embodiments, Rf or Rf ² is selected from the group consisting of:

Rf ^d -(0)r-CHF-(CF ₂ )n'-;

[Rf -(0) _t -C(L)H-CF ₂ -0] _m -W"-;

CF ₃ CFH-0-(CF ₂ )p'-;

CF ₃ -(0-CF ₂ ) _z -; and

CF ₃ -0-(CF ₂ ) ₃ -0-CF ₂ -;

wherein

Rf and Rf independently represent a partially or fully fluorinated alkyl group having from 1 to 10 carbon atoms and optionally interrupted with at least one oxygen atom;

L is selected from the group consisting of F and CF ₃ ;

W" is selected from the group consisting of alkylene and arylene;

r is 0 or 1, wherein when r is 0, then Rf is interrupted with at least one oxygen atom; t is 0 or 1;

m’ is 1, 2, or 3;

n ¹ is 0 or 1;

each p ¹ is independently a number from 1 to 6; and z is a number from 2 to 7.

In some of these embodiments, Rf or Rf ² has a molecular weight of up to 600 grams per mole (in some embodiments, up to 500, 400, or even up to 300 grams per mole). Rf ¹ and RP independently represent a partially or fully florinated alkyl group having from 1 to 10 carbon atoms and optionally interrupted with at least one oxygen atom. Rf ¹ and RP include linear and branched alkyl groups. In some embodiments, Rf ¹ and/or RP is linear. In some embodiments, RP and RP independently represent a fully fluorinated alkyl group having up to 6 (in some embodiments, 5, 4, 3, 2, or 1) carbon atoms. In some embodiments, RP and RP independently represent a fully fluorinated alkyl group interrupted with at least one oxygen atom, of which the alkyl groups between oxygen atoms have up to 6 (in some embodiments, 5, 4, 3, 2, or 1) carbon atoms, and wherein the terminal alkyl group has up to 6 (in some embodiments, 5, 4, 3, 2, or 1) carbon atoms. In some embodiments, RP and RP independently represent a partially fluorinated alkyl group having up to 6 (in some embodiments, 5, 4, 3, 2, or 1) carbon atoms and up to 2 hydrogen atoms.

In some embodiments, RP and RP independently represent a partially fluorinated alkyl group having up 2 hydrogen atoms interrupted with at least one oxygen atom, of which the alkyl groups between oxygen atoms have up to 6 (in some embodiments, 5, 4, 3, 2, or 1) carbon atoms, and wherein the terminal alkyl group has up to 6 (in some embodiments, 5, 4, 3, 2, or 1) carbon atoms.

In some embodiments of Rf and Rf ² , RP and RP are independently represented by formula R _f ¹ -[OR _f ² ] _a -[OR _f ³ ] _b -. R _f ¹ is a perfluorinated alkyl group having from 1 to 6 (in some embodiments, 1 to 4) carbon atoms. R _f ² and R _f ³ are each independently perfluorinated alkylene having from 1 to 4 carbon atoms "a" and b are each independently a number having a value from 0 to 4, and the sum of "a" and b is at least 1. In some of these embodiments, t is 1, and r is 1.

In some embodiments of Rf and Rf ² , RP and RP are independently represented by formula R _f ⁴ -[0R _f ⁵ ] _a' -[0R _f ⁶ ] _b -0-CF ₂ -. R _f ⁴ is a perfluorinated alkyl group having from 1 to 6 (in some

embodiments, 1 to 4) carbon atoms. R _f ⁵ and R _f ⁶ are each independently perfluorinated alkylene having from 1 to 4 carbon atoms a ¹ and b ¹ are each independently numbers having a value from 0 to 4. In some of these embodiments, t is 0, and r is 0.

In some embodiments of Rf or Rf ² , RP and RP are independently represented by formula R _f ⁷ -(OCF ₂ ) _p -, wherein p’ is an integer of 1 to 6 (in some embodiments, 1 to 4), and R _f ⁷ is selected from the group consisting of a partially fluorinated alkyl group having 1, 2, 3, 4, 5, or 6 carbon atoms and 1 or 2 hydrogen atoms and a fully fluorinated alkyl group having 1, 2, 3 or 4 carbon atoms.

In some embodiments of Rf or RP, RP and RP are independently represented by formula R _f ⁸ -0-(CF ₂ ) _p -, wherein p’ is a number from 1 to 6 (in some embodiments, 1 to 4) and R _f ⁸ is selected from the group consisting of a partially fluorinated alkyl group having 1, 2, 3, 4, 5, or 6 carbon atoms and 1 or 2 hydrogen atoms and a fully fluorinated alkyl group having 1, 2, 3 or 4 carbon atoms.

In some embodiments of Rf or Rf ² , L is selected from the group consisting of F and CF ₃ . In some embodiments, L is F. In other embodiments, L is CF ₃ . In some embodiments of Rf or Rf ² , W" is selected from the group consisting of alkylene and arylene. Alkylene includes linear, branched, and cyclic alkylene groups having from 1 to 10 (in some embodiments, 1 to 4) carbon atoms. In some embodiments, W" is methylene. In some embodiments, W" is ethylene. Arylene includes groups having 1 or 2 aromatic rings, optionally having at least one heteroatom (e.g., N, O, and S) in the ring, and optionally substituted with at least one alkyl group or halogen atom. In some embodiments, W" is phenylene.

In some embodiments of Rf or Rf ² , t is 0 or 1. In some embodiments, t is 1. In some

embodiments, t is 0. In embodiments wherein t is 0, RF is typically interrupted by at least one oxygen atom.

In some embodiments of Rf or Rf ² , m’ is 1, 2, or 3. In some embodiments, m’ is 1.

In some embodiments of Rf or Rf ² , n' is 0 or 1. In some embodiments, n' is 0. In some embodiments, n' is 1.

In some embodiments of Rf or Rf ² , p' is a number from 1 to 6 (i.e., 1, 2, 3, 4, 5, or 6). In some embodiments, p' is 1, 2, 5, or 6. In some embodiments, p' is 3. In some embodiments, p' is 1 or 2. In some embodiments, p' is 5 or 6.

In some embodiments of Rf or Rf ² , z is a number from 2 to 7 (i.e., 2, 3, 4, 5, 6, or 7). In some embodiments, z is an integer from 2 to 6, 2 to 5, 2 to 4, or 3 to 4.

Other useful Rf structures include partially fluorinated Rf or Rf ² groups disclosed, for example, in PCT International Pub. No. WO 2008/154345 A1 (Dams et ak), pages 8 to 10, the disclosure of which is incorporated herein by reference.

For any of the embodiments of the first divalent units, R ¹ is hydrogen or methyl. In some embodiments, R ¹ is hydrogen. In some embodiments, R ¹ is methyl.

The polyalkyleneoxy group in the second divalent unit of the fluorinated polymers useful for practicing the present disclosure can comprise a plurality (i.e., multiple) of repeating alkyleneoxy groups having from 2 to 4 or 2 to 3 carbon atoms (e.g., -CH2CH2O-, -CF^CFyCFFO-, -CFFCF^CFyO-, -CH2CH2CH2O-, -CH(CH ₂ CH ₃ )CH ₂ 0-, -CH ₂ CH(CH ₂ CH ₃ )0-, or -CH ₂ C(CH ₃ ) ₂ 0-). In some embodiments, the segment comprises a plurality of ethoxy groups, propoxy groups, or combinations thereof. The polyalkyleneoxy segment may have a number average molecular weight of at least 200, 300, 500, 700, or even at least 1000 grams per mole up to 2000, 4000, 5000, 8000, 10000, 15,000, or even up to 20000 grams per mole. Two or more differing alkyleneoxy groups may be distributed randomly in the series or may be present in alternating blocks. The polyalkyleneoxy group may be pendant from the polymer chain, or it may be a segment incorporated into the polymer backbone.

In some embodiments, the fluorinated polymer comprises at least one (e.g., at least 1, 2, 5, 10, 15, 20, or at least 25) second divalent unit represented by formula:

XIIIA

In formulas XIIIA, each R ² is independently hydrogen or methyl (in some embodiments, hydrogen and in some embodiments, methyl). Each R ³ is independently alkyl having up to 4 carbon atoms (e.g., methyl, ethyl, n-propyl, isopropyl, butyl, isobutyl, or t-butyl) or hydrogen. Each R ¹⁰ O is independently selected from the group consisting of -CH2CH2O-, -CH(CH ₃ )CH ₂ 0-, -CH2CH2CH2O-, -CH ₂ CH(CH ₃ )0-, -CH2CH2CH2CH2O-, -CH(CH ₂ CH ₃ )CH ₂ 0-, -CH ₂ CH(CH ₂ CH ₃ )0-, and -CH ₂ C(CH ₃ ) ₂ 0-. In some embodiments, each R ¹⁰ O independently represents -CH2CH2O-, -CH(CH ₃ )CH ₂ 0- or -CH ₂ CH(CH ₃ )0-. Each s is independently a value from 5 to 300 (in some embodiments, from 10 to about 250, or from 20 to about 200).

In some embodiments, the fluorinated polymer comprises at least one (e.g., at least 1, 2, 5, 10, 15, 20, or at least 25) second divalent unit represented by formula:

XIII

In formulas XII and XIII, each R ² is independently hydrogen or methyl (in some embodiments, hydrogen and in some embodiments, methyl). Each R ³ is independently alkyl having up to 4 carbon atoms (e.g., methyl, ethyl, n-propyl, isopropyl, butyl, isobutyl, or t-butyl) or hydrogen. EO represents -CH2CH2O-. Each R ⁴ 0 is independently selected from the group consisting of-CH(CH ₃ )CH ₂ 0-, -CH2CH2CH2O-, -CH ₂ CH(CH ₃ )0-, -CH2CH2CH2CH2O-, -CH(CH ₂ CH ₃ )CH ₂ 0-, -CH ₂ CH(CH ₂ CH ₃ )0-, and

-CH ₂ C(CH ₃ ) ₂ 0-. In some embodiments, each R ⁴ 0 independently represents -CH(CH ₃ )CH ₂ 0- or -CH ₂ CH(CH ₃ )0-). Each p is independently a value from 0 to 150 (in some embodiments, from 7 to about 130, or from 14 to about 130); and each q is independently a value from 0 to 150 (in some embodiments, from about 20 to about 100, 1 to 55, or from about 9 to about 25). The sum p + q is at least 5 (in some embodiments, at least 10 or at least 20.) In some embodiments, the ratio p/q has a value from at least 0.5, 0.75, 1 or 1.5 to 2.5, 2.7, 3, 4, 5, or more.

In some embodiments, the second divalent unit is represented by formula:

XV

wherein p, q, R ² , EO, and R ⁴ 0 are as defined above for formulas XII and XIII in any of their embodiments.

In some embodiments the second divalent unit may be a sulfur-terminated segment (e.g., -S(0)O-2-C _S H2S-C(0)-0-(EO)P-C(0)-C _S H _2S -S(0)O-2-,

-S(0)o-2-C ₃ H2s-C(0)-0-(EO)p-(R ⁴ 0) _q -(EO) _p -C(0)-C ₃ H2s-S(0)o-2-, or

-S(0)o-2-C ₃ H2s-C(0)-0-(PO)q-(EO)p-(PO)q-C(0)-CsH2s-S(0)o-2-, wherein p, q, EO, and R ⁴ 0 are as defined above for formulas XII and XIII in any of their embodiments and s is an integer from 1 to 5, or in some embodiments, 2 to 3).

In some embodiments, the second divalent units are present in an amount of at least 30, 40, 50,

60, or 70 percent by weight, based on the total weight of the fluorinated polymer.

In some embodiments, the fluorinated polymer is a nonionic polymer. When the fluorinated polymers useful for practicing the present disclosure include first and second divalent units, optionally divalent units represented by formula XX, below, but no third divalent units described below, they would generally be understood to be nonionic polymers. The term“nonionic” refers to being free of ionic groups (e.g., salts) or groups (e.g., -CO ₂ H, -SO ₃ H, -OSO ₃ H, -R(=0)(OH) ₂ ) that are readily substantially ionized in water.

In some embodiments, fluorinated polymers useful for practicing the present disclosure can be considered anionic polymers. In some of these embodiments, the fluorinated polymers further comprise at least one (e.g., at least 1, 2, 5, 10, 15, 20, or at least 25) anionic third divalent unit represented by formula:

XVIII

In formulas XVI, XVII, and XVIII, Q ¹ is -0-, -S-, or -N(R ⁷ )- (in some embodiments, -0-). Each R' is independently hydrogen or methyl (in some embodiments, hydrogen, and in some embodiments, methyl). Each R ⁷ is independently hydrogen or alkyl having from 1 to 4 carbon atoms (e.g., methyl, ethyl, n- propyl, isopropyl, butyl, isobutyl, or t-butyl). V is alkylene that is optionally interrupted by at least one ether linkage (i.e., -0-) or amine linkage (i.e., -N(R ⁷ )-). In some embodiments, V is alkylene having from 2 to 4 (in some embodiments, 2) carbon atoms. Each Y is independently selected from the group consisting of hydrogen, a counter cation, and a bond to the hydrocarbon-bearing formation in the method disclosed herein; and each Z is independently selected from the group consisting of -P(0)(OY) ₂ , -O- P(0)(OY)2, -SO3Y, -O-SO3Y, and -CO2Y. In some embodiments, Y is hydrogen. In some embodiments, Y is a counter cation. Examples of Y counter cations include alkali metal (e.g., sodium, potassium, and lithium), 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, for example, of treated hydrocarbon-bearing formations, Y is a bond to the hydrocarbon bearing formation.

In some embodiments, including any of the aforementioned embodiments, the fluorinated polymers further comprise at least one (e.g., at least 1, 2, 5, 10, 15, 20, or at least 25) third divalent unit represented by formula:

XIX

In formula XIX, R’, Q ¹ , R ⁷ , and V include any of the embodiments described above for formulas XVI, XVII, and XVIII. Z ¹ is selected from the group consisting of -N(R ⁹ )2; -N(R ⁹ ) ₂ (0); -[N(R ⁸ )3] ⁺ M ,

-N ⁺ (R ⁸ )2-(CH2) _g -S03Y ¹ , and -N ⁺ (R ⁸ ) ₂ -(CH ₂ ) _g -C0 ₂ Y ¹ , wherein each R ⁸ is independently selected from the group consisting of hydrogen and alkyl having from 1 to 6 carbon atoms (e.g., methyl, ethyl, n-propyl, isopropyl, butyl, isobutyl, t-butyl, n-pentyl, isopentyl, n-hexyl). Each R ⁹ is independently selected from the group consisting of hydrogen and alkyl having from 1 to 6 carbon atoms (e.g., methyl, ethyl, n-propyl, isopropyl, butyl, isobutyl, t-butyl, n-pentyl, isopentyl, n-hexyl), wherein alkyl is optionally substituted by at least one halogen, hydroxyl, alkoxy, nitro, or nitrile group, or two R ⁹ groups may join to form a 5 to 7- membered ring optionally containing at least one O, N, or S and optionally substituted by alkyl having 1 to 6 carbon atoms. Each g is independently an integer from 1 to 6 (i.e., 1, 2, 3, 4, 5, or 6). M is a counter anion (e.g., acetate, chloride, iodide, ethyl sulfate and methyl sulfate); and Y ¹ is selected from the group consisting of hydrogen and free anion. In some embodiments, R' and R ¹ are each independently hydrogen or methyl. In some embodiments of M-, the counter anion is present in the hydrocarbon-bearing formation.

In some embodiments, fluorinated polymers useful for practicing the present disclosure can be considered cationic or amphoteric. In some embodiments in which the fluorinated polymer includes a third divalent unit represented by formula XIX, Z ¹ is -[N(R ⁸ )3] ⁺ M , and the fluorinated polymer is a cationic polymer. In other embodiments where Z ¹ is -[N(R ⁸ )3] ⁺ M , if the fluorinated polymer also includes an anionic divalent unit (e.g., represented by formula XVI, XVII, or XVIII) the fluorinated polymer is an amphoteric polymer.

In some embodiments in which the fluorinated polymer includes a third divalent unit represented by formula XIX, Z ¹ is selected from the group consisting of -N ⁺ (R ⁸ )2-(CH2) _g -S03Y ¹ and

-N ⁺ (R ⁸ ) ₂ -(CH ₂ ) _g -C0 ₂ Y ¹ , and the polymer can be considered an amphoteric polymer. In these

embodiments, it is generally understood that under neutral pH conditions (e.g., pH 6 to 8), Y ¹ in Z ¹ is typically a free anion (i.e., Z ¹ is -N ⁺ ( R ⁸ )2-(CH2) _g -SO3 or -N ⁺ (R ⁸ ) ₂ -(CH ₂ ) _g -C0 ₂ -). Under strongly acidic conditions (e.g, pH of up to 4), Y ¹ in Z ¹ is hydrogen.

In some embodiments, fluorinated polymers useful for practicing the present disclosure include divalent units comprising a pendant amino group. It will be understood by a person having ordinary skill in the art that an amino group is neutral -NR2. In some embodiments in which the fluorinated polymer includes a third divalent unit represented by formula XIX, Z ¹ is -N(R ⁹ )2, and the fluorinated polymer is nonionic. The nitrogen atom is understood to be neutral and to have a lone pair of electrons, features that distinguish them from quaternary ammonium compounds, which have a permanent positive charge regardless of pH.

In some embodiments, third divalent unit represented by formula XVI, XVII, XVIII, or IX, for example, are present in the fluorinated polymer in an amount up to 20, 15, 10, or 5 percent by weight, based on the total weight of the fluorinated polymer.

Advantageously, in embodiments in which the fluorinated polymer includes a third divalent unit represented by formula XVI, XVII, XVIII, or IX, compositions and methods of the present disclosure are useful for changing the wettability of a variety of materials found in hydrocarbon-bearing formations, including sandstone, limestone, and bauxite proppants. In some of these embodiments, the fluorinated polymer is anionic (e.g., having a third divalent unit represented by formula XVI, XVII, or XVIII) or amphoteric. Advantageously, in these embodiments, the compositions and methods of the present disclosure may be more versatile than other treatment methods which are effective with only certain substrates (e.g., sandstone).

Useful polymers can also be prepared, for example, by polymerizing a mixture of components typically in the presence of an initiator. By the term "polymerizing" it is meant forming a polymer or oligomer that includes at least one identifiable structural element due to each of the components.

Typically the polymer that is formed has a distribution of molecular weights and compositions. The polymer may have one of many structures (e.g., a random graft copolymer or a block copolymer). The components that are useful for preparing the polymers disclosed herein include a fluorinated free- radically polymerizable monomer independently represented by formula

Rf-Q-(C _m H _2m )-0-C(0)-C(R ¹ )=CH ₂ , Rf-S0 ₂ -N(R)-(CnH _2n )-0-C(0)-C(R ¹ )=CH ₂ , or

Rf-C(0)-N(R ¹ )-(C _n H _2n )-0-C(0)-C(R)=CH ₂ , wherein Rf, R ¹ , R, m, and n are as defined above.

Some compounds of Formula Rf-Q-(C _m H _2m )-0-C(0)-C(R ¹ )=CH ₂ , 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, 3,3,4,4,5,5,6,6,6-nonafluorohexyl 2-methylacrylate from Indofine Chemical Co.,

Hillsborough, NJ, lH,lH,2H,2H-perfluorooctylacrylate from ABCR, Karlsruhe, Germany, and

2,2,3,3,4,4,5,5-octafluoropentyl acrylate and methacrylate and 3,3,4,4,5,6,6,6-octafluoro-5- (trifluoromethyl)hexyl methacrylate from Sigma- Aldrich, St. Uouis, MO). Others can be made by known methods (see, e.g., EP1311637 Bl, published April 5, 2006, for the preparation of 2, 2, 3, 3, 4,4,4- heptafluorobutyl 2-methylacrylate). Compounds wherein Q is -S0 ₂ N(R)- can be made according to methods described in, 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.

A fluoropolyether monomer of formula Rf-(C0)NHCH ₂ CH ₂ 0(C0)C(R)=CH ₂ , for example, can be prepared by first reacting Rf-C(0)-OCH ₃ , for example, with ethanolamine to prepare alcohol- terminated Rf-(C0)NHCH ₂ CH ₂ 0H, which can then be reacted with methacrylic acid, methacrylic anhydride, acrylic acid or acryloyl chloride to prepare the compound, wherein R is methyl or hydrogen, respectively. Other amino alcohols (e.g., amino alcohols of formula NR ¹ H(C _n H2 _n )OH) can be used in this reaction sequence to provide compounds of Formula X, wherein Q is -C(0)-N(R ¹ )-, and R ¹ and m are as defined above. In further examples, an ester of formula Rf-C(0)-OC]¾ or a carboxylic acid of formula Rf-C(0)-OH can be reduced using conventional methods (e.g., hydride, for example sodium borohydride, reduction) to an alcohol of formula Rf-CFbOFl. The alcohol of formula Rf-CFbOFl can then be reacted with methacryloyl chloride, for example, to provide a perfluoropolyether monomer of formula Rf- CH ₂ 0(C0)C(R)=CH ₂ . 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 II, are incorporated herein by reference.

In some embodiments, the components that are useful for preparing the fluorinated polymers disclosed herein include a poly(alkyleneoxy) acrylate (e.g., monoacrylate, diacrylate, or a mixture thereof). Some alkyleneoxy-containing polymerizable compounds are commercially available (e.g., polyoxyalkylene glycol acrylates and diacrylates (e.g., diethylene glycol diacrylate, tri(ethylene glycol) dimethacrylate, tri(ethylene glycol) divinyl ether, and CH2=CHC(0)0(CH2CH20)7-9H available, for example, from Nippon Oil & Fats Company, Tokyo, Japan under the trade designation "BLEMMER"). Other useful alkyleneoxy-containing polymerizable compounds can be prepared by known methods, for example, combining one or two equivalents of acryloyl chloride or acrylic acid with a polyethylene glycol or a monoalkyl ether thereof having a molecular weight of about 200 to 10,000 grams per mole (e.g., those available from Dow Chemical Company, Midland, MI, under the trade designation

"CARBOWAX") or a block copolymer of ethylene oxide and propylene oxide having a molecular weight of about 500 to 15000 grams per mole (e.g., those available from BASF Corporation, Ludwigshafen, Germany, under the trade designation "PLURONIC"). The reaction of acrylic acid with a poly(alkylene oxide) is typically carried out in the presence of an acid catalyst and a polymerization inhibitor at an elevated temperature in a suitable solvent; (see, e.g., Example 1 of U. S. Pat. No. 3,787,351 (Olson), the disclosure of which is incorporated herein by reference). In embodiments wherein the fluorinated polymer includes divalent units represented by formula XII, XIII, or XIIIA, the alkyleneoxy-containing polymerizable compound can be at least one of H0-(E0) _p -(R ⁴ 0) _q -(E0) _p -C(0)-C(R ² )=CH ₂ , R ³ 0-(R ⁴ 0) _q -(E0)p-(R ⁴ 0) _q -C(0)-C(R ² )=CH ₂ , or R ³ O-(R ¹⁰ O) _s -C(O)-C(R ² )=CH ₂ , wherein R ² , R ³ , R ⁴ 0, R ¹⁰ O, EO, p, q, and s are as defined above. In embodiments wherein the fluorinated polymer includes divalent units represented by formula XIV or XV, the alkyleneoxy-containing polymerizable compound can be CH ₂ =C(R ² )-C(0)0-(E0) _p -(R ⁴ 0) _q -(E0) _p -C(0)-C(R ² )=CH ₂ or

CH ₂ =C(R ² )-C(0)0-(R ⁴ 0) _q -(E0) _p -(R ⁴ 0) _q -C(0)-C(R ² )=CH ₂ , wherein R ² , R ³ , R ⁴ 0, EO, p, and q are as defined above.

Sulfur-terminated polyalkyleneoxy segments can be incorporated into the fluorinated polymers by copolymerization of a difunctional mercaptan, which can react with fluorinated acrylates (e.g., Rf-Q-(C _m H _2m )-0-C(0)-C(R ¹ )=CH ₂ or Rf-S0 ₂ -(C _n H _2n )-0-C(0)-C(R ¹ )=CH ₂ ) under free-radical polymerization conditions to provide block copolymers. Examples of difunctional mercaptans include HS-C _S H _2S -C(0)-0-(E0) _P -C(0)-C _S H _2S -SH, HS- C _s H _2s -C(0)-0-(E0) _p -(R ⁴ 0) _q -(E0) _p -C(0)-C ₃ H _2s -SH, or HS-C ₃ H _2s -C(0)-0-(P0) _q -(E0) _p -(P0) _q -C(0)-C ₃ H _2s -SH, wherein p, q, EO, and R ⁴ 0 are as defined above for formulas XII and XIII in any of their embodiments and s is an integer from 1 to 5, or in some embodiments, 2 to 3. The resulting polymer or oligomer can then optionally be oxidized using conventional techniques. Difunctional mercaptans can be prepared, for example, by reaction of a diol- functional polyethylene glycol or a block copolymer of ethylene oxide and propylene oxide with, for example, mercaptoacetic acid or mercaptopropionic acid. In other embodiments, polyalkyleneoxy- containing diacrylates can be treated with H ₂ S or other sulfhydryl-containing compounds according to the methods of U.S. Pat. No. 3,278,352 (Erickson), incorporated herein by reference, to provide mercaptan- terminated polyalkyleneoxy compounds.

Divalent units of Formulas XVI, XVII, and XVIII can be incorporated into the fluorinated polymers disclosed herein by copolymerization of a compound of formula

Rf-Q-(C _m H _2m )-0-C(0)-C(R ¹ )=CH ₂ or Rf-S0 ₂ -N(R)-(C _n H _2n )-0-C(0)-C(R ¹ )=CH ₂ with a compound of formula Y00C-C(R')=CH ₂ , (Y0) ₂ (0)P-C(R')=CH ₂ , and Z-V-Q ¹ C(0)-C(R')=CH ₂ , respectively. Useful compounds of these formulas include acrylic acid, methacrylic acid, b-carboxyethyl acrylate, b- carboxyethyl methacryate, vinyl phosphonic acid, ethylene glycol methacrylate phosphate, and 2- acrylamido-2 -methyl- 1 -propane sulfonic acid (AMPS).

Divalent units of Formula XIX can be incorporated into the fluorinated polymers disclosed herein by copolymerization of a compound of formula Rf-Q-(C _m H _2m )-0-C(0)-C(R ¹ )=CH ₂ or

Rf-S0 ₂ -N(R)-(C _n H _2n )-0-C(0)-C(R ¹ )=CH ₂ with a compound of formula Z ¹ -V-Q ¹ C(0)-C(R')=CH ₂ . Useful compounds for preparing compound of formula Z ¹ -V-Q ¹ C(0)-C(R')=CH ₂ include aminoalkyl

(meth)acrylates such as N,N-diethylaminoethylmethacrylate, N,N'-dimethylaminoethylmethacrylate and N-t-butylaminoethylmethacrylate, which are commercially available, for example, from Sigma-Aldrich and can be quatemized using conventional techniques, for example, by reaction with an alkyl halide (e.g., bromobutane, bromoheptane, bromodecane, bromododecane, or bromohexadecane) or a dialkylsulphate (e.g. dimethyl sulfate or diethyl sulfate) in a suitable solvent and optionally in the presence of a free- radical inhibitor to provide a compound wherein Z ¹ is -[N(R ⁸ )3] ⁺ M . Useful compounds having formula Z ¹ -V-Q ¹ C(0)-C(R')=CH ₂ include N,N-dimethylaminoethyl acrylate methyl chloride quaternary and N,N- dimethylaminoethyl methacrylate methyl chloride quaternary available from Ciba Specialty Chemicals, Basel, Switzerland, under the trade designations "CIBA AGEFLEX FA1Q80MC" and "CIBA AGEFLEX FM1Q75MC", respectively.

Divalent units of Formula XIX can be incorporated into the fluorinated polymers disclosed herein by copolymerization of a compound of formula Rf-Q-(C _m H _2m )-0-C(0)-C(R ¹ )=CH ₂ or

Rf-S0 ₂ -N(R)-(C _n H _2n )-0-C(0)-C(R ¹ )=CH ₂ with a compound of formula N(R ⁸ ) ₂ -V-Q ¹ C(0)-C(R')=CH ₂ . Useful compounds of formula N(R ⁸ ) ₂ -V-Q ¹ C(0)-C(R)=CH ₂ include aminoalkyl (meth)acrylates such as N,N-diethylaminoethylmethacrylate, N,N'-dimethylaminoethylmethacrylate and N-t- butylaminoethylmethacrylate, which are commercially available, for example, from Sigma-Aldrich and can be treated with 1,3-propanesultone, acrylic acid, chloroacetic acid, or 2-bromoethanesulfonic acid using the methods described in U.S. Pat. No. 5,144,069 (Stem et al.) and U.S. Pat. No. 5,468,353 (Anich et al.), the disclosure of which methods are incorporated herein by reference.

In some embodiments, fluorinated polymers useful for practicing the present disclosure further comprise at least one (e.g., at least 1, 2, 5, 10, 15, 20, 25, or at least 50) divalent unit represented by Formula XX:

XX

wherein each R ⁶ is independently hydrogen or methyl (in some embodiments, hydrogen, in some embodiments, methyl), and wherein each R ⁵ 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 12 to 25) carbon atoms. In some embodiments, each R ⁵ is independently alkyl having up to 8 carbon atoms (e.g., methyl, ethyl, n-propyl, isopropyl, n- butyl, iso-butyl, n-pentyl, neopentyl, hexyl, heptyl, or octyl). In some embodiments, R ⁵ is hexadecyl or octadecyl. In some of these embodiments, the fluorinated polymer is preparable by including at least one compound represented by formula R ⁵ -0-C(0)-C(R ⁶ )=CH ₂ in the components to be polymerized.

Compounds of formula R ⁵ -0-C(0)-C(R ⁶ )=CH ₂ , (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. Fouis, MO; VWR International, West Chester, PA; Monomer-Polymer & Dajac Fabs, Festerville, PA; Avocado Organics, Ward Hill, MA; and Ciba Specialty Chemicals, Basel, Switzerland) or may be synthesized by conventional methods. Some compounds of formula R ⁵ -0-C(0)-C(R ⁶ )=CH ₂ are available as single isomers (e.g., straight-chain isomer) of single compounds. Other compounds of formula R ⁵ -0-C(0)-C(R ⁶ )=CH ₂ 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. In some embodiments, divalent units represented by formula XX are present in the fluorinated polymer in an amount up to 20, 15, 10, or 5 percent by weight, based on the total weight of the fluorinated polymer.

Fluorinated polymers useful for practicing the present disclosure may also be preparable by adding additional monomers to the polymerization reaction. For example, a compound formula

H0-V-0-C(0)-C(R')=CH ₂ , wherein R and V are as defined above may be used. Examples of these monomers include hydroxyethyl methacrylate. Other examples include vinylidene chloride, vinyl chloride, silicone acrylates available, for example, from Shin-Etsu Silicones of America, Inc., Akron, OH, under the trade designation "X22-2426", and urethane acrylates available, for example, from Sartomer Company, Exton, PA under the trade designation "CN966J75. 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); olefinic hydrocarbons which may contain at least one halogen (e.g., ethylene, propylene, isobutene, 3 -chloro-1 -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, fluorinated polymers useful for practicing the present disclosure are free of divalent units comprising a pendant silane group and free of silane terminal groups.

The polymerization reaction can be carried out in the presence of an added 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. 6,664,354 (Savu et ah), the disclosure of which, relating to free-radical initiators, is incorporated herein by reference. In some embodiments, the polymer or oligomer that is formed is a random graft copolymer. In some embodiments, the polymer or oligomer that is formed is a block copolymer.

In some embodiments, the polymerization reaction is carried out in solvent. The components may be present in the reaction medium at any suitable concentration, (e.g., from about 5 percent to about 80 percent by weight based on the total weight of the reaction mixture). Illustrative examples of suitable solvents include aliphatic and alicyclic hydrocarbons (e.g., hexane, heptane, cyclohexane), aromatic solvents (e.g., benzene, toluene, xylene), 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, l,l,2-trichloro-l,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 °C to about 200 °C (in some embodiments, from about 40 °C to about 100 °C, or from about 50 °C to about 80 °C).

Free-radical polymerizations may be carried out in the presence of chain transfer agents. Typical chain transfer agents that may be used in the preparation compositions according to the present invention include hydroxyl-substituted mercaptans (e.g., 2-mercaptoethanol, 3-mercapto-2-butanol, 3-mercapto-2- propanol, 3 -mercapto-1 -propanol, and 3 -mercapto- 1,2-propanediol (i.e., thioglycerol)); polyethylene glycol)-substituted mercaptans; carboxy-substituted mercaptans (e.g., mercaptopropionic acid or mercaptoacetic acid): amino-substituted mercaptans (e.g., 2-mercaptoethylamine); difunctional mercaptans (e.g., di(2-mercaptoethyl)sulfide); and aliphatic mercaptans (e.g., octylmercaptan, dodecylmercaptan, and octadecylmercaptan).

Adjusting, for example, the concentration and activity of the initiator, the concentration of each of the reactive monomers, 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 polymer or copolymer.

In some embodiments, fluorinated polymers disclosed herein have weight average molecular weights in a range from 1000 grams per mole to 100,000 grams per mole. In some embodiments, the weight average molecular weight is at least 2000, 3000, 4000, 5000, 6000, 7000, 8000, 9000, or 10000 grams per mole up to 30,000, 40,000, 50,000, 60,000, 70,000, 80,000, or up to 90,000 grams per mole. Fluorinated polymers disclosed herein typically have a distribution of molecular weights and

compositions. Weight average molecular weights can be measured, for example, by gel permeation chromatography (i.e., size exclusion chromatography) using techniques known to one of skill in the art.

Typically, in treatment compositions useful for practicing the methods described herein, the fluorinated polymer is present in the treatment composition in an amount of 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 fluorinated polymer 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, 0.5 to 2, or 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 fluorinated polymer in the treatment compositions may also be used and may be desirable for some applications.

Compositions of the present disclosure comprise two solvents. The first solvent is ethylene glycol, propylene glycol (i.e., 1,2-propanediol), 1,3 -propanediol, or 2,3-butanediol. The first solvent is typically ethylene glycol, propylene glycol, or 2,3-butanediol. In some embodiments, the first solvent is propylene glycol or 2,3-butanediol. In some embodiments, the first solvent is propylene glycol (i.e., 1,2- propanediol). The second solvent is a linear monohydroxy alcohol having from 4 to 12 carbon atoms and optionally at least one (in some embodiments, one, two, or three) ether linkage. The monohydroxy alcohol therefore has one C-O-H group and optionally at least one C-O-C linkage. In some embodiments, the second solvent is a linear monohydroxy alcohol having from 4 to 12 carbon atoms and optionally one ether linkage. The term“linear” refers to the carbon chain. Therefore, primary and secondary alcohols can both be linear monohydroxy alcohols. Examples of useful second solvents include 1-butanol, 2- butanol, 1-pentanol, 2-pentanol, 1-hexanol, 2-hexanol, 1-heptanol, 1-octanol, 1-decanol, 1-dodeconal, 2- butoxyethanol, diethylene glycol monomethyl ether, and triethylene glycol monomethyl ether. In some embodiments, the second solvent is 1-pentanol, 1-hexanol, 1-heptanol, 1-octanol, or 2-butoxyethanol. In some embodiments, the second solvent is 1-pentanol, 1-hexanol, or 2-butoxyethanol. In some embodiments, the second solvent is 1-pentanol or 1-hexanol.

The first and second solvents useful in the compositions and methods of the present disclosure have flashpoints of greater than 30 °C, in some embodiments, at least 40 °C, at least 45 °C, at least 50 °C, or at least 55 °C. For the purposes of this application, the flashpoint of the organic solvent is measured by the closed cup method. Flashpoint is commonly used to classify materials as flammable or combustible. As defined by the U.S. Occupational Safety and Health Administration (OSHA), a flammable liquid has a flashpoint below 100 °F (37.8 °C). Flammable liquids may have components with flashpoints of 100 °F (37.8 °C) or higher if such components make up less than 99 percent of the total volume of the liquid. As defined by the U.S. Department of Transportation (DOT), a flammable liquid has a flashpoint below 141 °F (60.5 °C) or has a flashpoint at or above 100 °F (37.8 °C) and is intentionally heated and offered for transportation or transported at or above its flashpoint in a bulk package. Flammable liquids may have components with flashpoints of 100 °F (37.8 °C) or higher if such components make up less than 99 percent of the total volume of the liquid and the mixture is offered for transportation or transported at or above its flashpoint. A liquid is considered‘combustible’ when the flashpoint is above 60.5 °C according to DOT and above 37.8 °C according to OSHA. The UN Globally Harmonized System of Classification and Fabeling of Chemicals (GHS) is an international system created by the UN to address the classification of chemicals by types of hazard and harmonize hazard communication elements, including labels and safety data sheets. According to GHS, a category 1 flammable liquid has a flashpoint of less than 23 °C and a boiling point of up to 35 °C; a category 2 flammable liquid has a flashpoint of less than 23 °C and a boiling point of greater than 35 °C; a category 3 flammable liquid has a flashpoint of at least 23 °C and a boiling point of up to 60 °C; and a category 4 flammable liquid has a flashpoint of greater than 60 °C and a boiling point of up to 93 °C. In some embodiments, compositions according to the present disclosure may be considered nonflammable or combustible according to at least one of the above definitions. Therefore, the compositions may be used without requiring explosion-proof equipment and may be used in the field in regions where the outdoor temperature during the day can be up to 40 °C (104 °F) or even up to 60 °C (140 °F).

Although the solvent in the composition according to the present disclosure can include water and other organic solvents including a third solvent that may be a glycol or monohydroxy alcohol described above or a different solvent, the Examples, below, demonstrate that the combination of the first solvent and second solvent are unexpectedly effective at solubilizing brine found, for example, in a hydrocarbon bearing formation. It can be beneficial to simplify formulations by using the minimum number of solvents necessary. Accordingly, in some embodiments, the composition is substantially free of (in some embodiments, free of) a third solvent, different from the first and second solvents. In these embodiments, the first and second solvents make up at least 90, 95, 97, 98, 99, or 99.5 percent or more of the solvent in the composition.

Furthermore, in some embodiments, compositions of the present disclosure and/or useful for practicing the method disclosed herein include not more than 5, 4, 3, 2, 1, or 0.5 percent by weight of an organic solvent having a flashpoint up to 30 °C, in some embodiments, up to 40 °C, 45 °C, 50 °C, or 60 °C. In some embodiments, the compositions are free of such organic solvents. Organic solvents that have flashpoints up to 30 °C include certain alcohols (e.g., methanol, ethanol, and isopropanol); ketones (e.g., acetone and 2-butanone); and ethers (e.g., diethyl ether). While certain of these solvents (e.g., methanol, ethanol, isopropanol, acetone, and 2-butanone) have been found useful for solubilizing brine and/or condensate in hydrocarbon-bearing formations, these solvents are flammable, having flashpoints of 12 °C, 13 °C, 13 °C, -20 °C, -9 °C, respectively, which limits their utility in some applications, for example, in hot outdoor environments.

In some embodiments, the first and second solvents have a normal boiling point of less than 450 °F (232 °C), which may be useful, for example, to facilitate removal of the first and second solvents from a well after treatment. In some of these embodiments, the second solvent is 1-pentanol, 1-hexanol, 1- heptanol, 1-octanol, or 2-butoxyethanol.

In some embodiments, the first solvent is present in the solvent combination in an amount of at least 30, 40, 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 first and second solvents. In some embodiments, the solvent comprises up to 70, 60, 50, 40, 30, 20, or 10 percent by weight of the second solvent, based on the total weight of the first and second solvents. Examples of useful combinations of the first and second solvents include propylene glycol (50%)/l -butanol (50%), propylene glycol (60%)/l -butanol (40%), propylene glycol (70%)/l- butanol (30%), propylene glycol (80%)/l -butanol (20%), propylene glycol (90%)/ 1 -butanol (10%), propylene glycol (50%)/l-pentanol (50%), propylene glycol (60%)/l-pentanol (40%), propylene glycol (70%)/l-pentanol (30%), propylene glycol (80%)/l-pentanol (20%), propylene glycol (90%)/l-pentanol (10%), propylene glycol (50%)/l-hexanol (50%), propylene glycol (60%)/l-hexanol (40%), propylene glycol (70%)/l-hexanol (30%), propylene glycol (80%)/l-hexanol (20%), propylene glycol (90%)/l- hexanol (10%), propylene glycol (50%)/l-heptanol (50%), propylene glycol (60%)/l-heptanol (40%), propylene glycol (70%)/l-heptanol (30%), propylene glycol (80%)/l-heptanol (20%), propylene glycol (90%)/l-heptanol (10%), propylene glycol (50%)/2-butoxyethanol (50%), propylene glycol (60%)/2- butoxyethanol (40%), propylene glycol (70%)/2-butoxyethanol (30%), propylene glycol (80%)/2- butoxyethanol (20%), propylene glycol (90%)/2-butoxyethanol (10%), 2,3-butanediol (50%)/l -butanol (50%), 2,3-butanediol (60%)/l -butanol (40%), 2,3-butanediol (70%)/ 1 -butanol (30%), 2,3-butanediol (80%)/l-butanol (20%), 2,3-butanediol (90%)/ 1 -butanol (10%), 2,3-butanediol (50%)/l-pentanol (50%), 2,3-butanediol (60%)/l-pentanol (40%), 2,3-butanediol (70%)/l-pentanol (30%), 2,3-butanediol (80%)/l- pentanol (20%), 2,3-butanediol (90%)/l-pentanol (10%), 2,3-butanediol (50%)/l-hexanol (50%), 2,3- butanediol (60%)/l-hexanol (40%), 2,3-butanediol (70%)/l-hexanol (30%), 2,3-butanediol (80%)/l- hexanol (20%), 2,3-butanediol (90%)/l-hexanol (10%), 2,3-butanediol (50%)/l-heptanol (50%), 2,3- butanediol (60%)/l-heptanol (40%), 2,3-butanediol (70%)/l-heptanol (30%), 2,3-butanediol (80%)/l- heptanol (20%), 2,3-butanediol (90%)/l-heptanol (10%), 2,3-butanediol (50%)/2-butoxyethanol (50%), 2,3-butanediol (60%)/2-butoxyethanol (40%), 2,3-butanediol (70%)/2-butoxyethanol (30%), 2,3- butanediol (80%)/2-butoxyethanol (20%), and 2,3-butanediol (90%)/2-butoxyethanol (10%), wherein the percentages are by weight are based on the total weight of solvent.

The amount of solvent typically varies inversely with the amounts of other components in treatment compositions of the present disclosure and/or useful for 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 10, 20, 30, 40, or 50 percent by weight or more up to 60, 70, 80, 90, 95, 98, or 99 percent by weight, or more.

The ingredients for treatment compositions described herein including fluorinated polymers and solvent 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 of compositions and methods of the present disclosure, useful solvents at least partially solubilize brine in the hydrocarbon-bearing formation. By the term "solubilizes", it is meant that the solvent dissolves the water and the salts in the brine. "At least partially solubilize" includes dissolving all or nearly all (e.g., at least 95% including up to 100%) of the water and the salts in the brine. In some embodiments, useful solvents at least partially solubilize or at least partially displace liquid hydrocarbons in the hydrocarbon-bearing formation. Although not wishing to be bound by theory, it is believed that methods according to the present disclosure will provide more desirable results when the composition is homogeneous at the temperature(s) encountered in the hydrocarbon-bearing formation. Whether the treatment composition is homogeneous at the temperature can depend on many variables (e.g., concentration of the fluorinated polymer, solvent composition, brine concentration and composition, hydrocarbon concentration and composition, and the presence of other components (e.g., surfactants)). It is believed that once the treatment composition contacts a hydrocarbon-bearing formation (e.g., downhole), the downhole conditions will cause the fluorinated polymer to become less soluble in the composition and adsorb onto at least one of the formation or at least a portion of a plurality of proppants located in a fracture in the formation. Once adsorbed onto the formation or at least a portion of a plurality of proppants, the fluorinated polymer can modify the wetting properties of the formation and cause an increase in at least one of the gas or oil permeabilities in the formation, facilitating the removal of hydrocarbons and/or brine. The fluorinated polymer may remain on the rock for the duration of an extraction of hydrocarbons from the formation (e.g., 1 week, 2 weeks, 1 month, or longer). It is believed that low-foaming fluorinated polymers and compositions are more effective for increasing the gas permeability of hydrocarbon-bearing formations.

In some embodiments of methods and treated hydrocarbon-bearing formations disclosed herein, the hydrocarbon-bearing formation has brine. The brine present in the 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 before treatment. In some embodiments of the treatment compositions, the solvent at least partially solubilizes or at least partially displaces brine in the hydrocarbon-bearing formation. In some embodiments, the brine has at least 2, 3, 4, 5, 6, 7, 8, 9, or at least 10 weight percent dissolved salts (e.g., sodium chloride, calcium chloride, strontium chloride, magnesium chloride, potassium chloride, ferric chloride, ferrous chloride, and hydrates thereof), based on the total weight of the brine. Although not wanting to be bound by theory, it is believed that 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 treatment composition to dissolve or displace the quantity of brine present in the near wellbore region of the well without causing precipitation of the fluorinated polymer or salts. Hence, at a given temperature greater amounts of treatment compositions having lower brine solubility (i.e., treatment compositions that can dissolve a relatively lower amount of brine) will typically be needed than in the case of treatment compositions having higher brine solubility and containing the same fluorinated polymer at the same concentration.

In some embodiments, a mixture of an amount of the brine composition and the treatment composition, at the temperature of the hydrocarbon-bearing formation, is transparent and free of precipitated solids. 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 fluorinated polymer 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. Typically, the transparent mixture of the brine composition and the treatment composition does not separate into layers.

Phase behavior of a mixture of the brine composition and the treatment composition can be evaluated before 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, 10, or 5 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.

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 fluorinated polymer, 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 the first and second solvent described above, mixtures of the brine composition and the treatment composition are transparent, substantially free of precipitated solid, and 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. In some of these embodiments, the salinity of the brine is greater than 40,000 ppm (e.g., greater than 50,000, 60,000, or 75,000 ppm) total dissolved salt.

Typically and unexpectedly, treatment compositions of the present disclosure, which include the first and second solvents, are capable of solubilizing more brine (i.e., no salt precipitation or phase separation occurs) in the presence or absence of than fluorinated polymer than other combinations of solvents having relatively high flash points. For example, 2-butoxyethanol is preferred solvent in U.S. Pat. App. Pub. No. 2015/0315455 (Sayed et al.) and is described in U.S. Pat. No. 7,585,817 (Pope et al.) as being equivalent to or better than 1,2-propanediol in solubilizing brine in combinations with methanol, ethanol, or isopropanol. However, we have unexpectedly found that combinations of a linear monohydroxy alcohol having from 4 to 12 carbon atoms and optionally one ether linkage (i.e., the second solvent) and the first solvent disclosed herein solubilizes more brine than the combination of 2- butoxyethanol with the linear monohydroxy alcohol having from 4 to 12 carbon atoms. See, for example, Comparative Examples A to C vs. Examples 1 to 3 in the Examples, below. The data show that compositions including 1,2-propanediol and 1 -butanol, 1-pentanol, or 1-hexanol solubilize 30 weight percent (wt. %) brine or more while compositions including 2-butoxyethanol and 1 -butanol, 1-pentanol, or 1-hexanol solubilize less than 7% brine of the same brine. Also, other polyols and polyol ethers: diethylene glycol monomethyl ether, 1,3-butanediol, or 1,4-butanediol in a 70:30 ratio with second solvent 1-butanol, 1-pentanol, and 1-hexanol resulted in salt precipitation when 8.8 wt. % or less brine was added. (See Illustrative Examples GG to OO, below.)

The phase behavior of the 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 some embodiments of the 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. 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.

The hydrocarbon-bearing formation having both gas and liquid hydrocarbons may have gas condensate, black oil, or volatile oil and 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 m ³ /m ³ ). For example, a black oil may have a GOR in a range from about 100 (18), 200 (36), 300 (53), 400 (71), or 500 scf/stb (89 m ³ /m ³ ) up to about 1800 (320), 1900 (338), or 2000 scf/stb (356 m ³ /m ³ ). 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 m ³ /m ³ ). For example, a volatile oil may have a GOR in a range from about 2000 (356), 2100 (374), or 2200 scf/stb (392 m ³ /m ³ ) up to about 3100 (552), 3200 (570), or 3300 scf/stb (588 m ³ /m ³ ). In some embodiments, 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 fluorinated polymer 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. For example, a method of making a treatment composition useful for practicing the methods disclosed herein may include receiving (e.g., obtaining or measuring) data comprising the temperature and at least one of the hydrocarbon composition or the brine composition (including the brine saturation level and components of the brine) of a selected geological zone of a hydrocarbon-bearing formation. These data can be obtained or measured using techniques well known to one of skill in the art. A formulation may then be generated based at least in part on compatibility information concerning the fluorinated polymer, the solvent, the temperature, and at least one of the hydrocarbon composition or brine composition of the selected geological zone of the formation. In some embodiments, the compatibility information comprises information concerning phase stability of a mixture of the fluorinated polymer, the solvent, and a model brine composition, wherein the model brine composition is based at least partially on the brine composition of the geological zone of the formation. The phase stability of a solution or dispersion can be evaluated using the phase behavior evaluation described above. The phase behavior can be evaluated over an extended period of time (e.g., 1 hour, 12 hours, 24 hours, or longer) to determine if any precipitation or cloudiness is observed. In some embodiments, the compatibility information comprises information concerning solid (e.g., salts or asphaltenes) precipitation from a mixture of the fluorinated polymer, the solvent, a model brine composition, and a model hydrocarbon composition, wherein the model brine composition is based at least partially on the brine composition of the geological zone of the formation, and wherein the model hydrocarbon composition is based at least partially on the hydrocarbon composition of the geological zone of the formation. In addition to using a phase behavior evaluation, it is also contemplated that one may be able 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 or a computer database).

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 treatment compositions including a third divalent unit having a pendant ionic group, for example, may be useful for treating a wider variety of formations than other treatment compositions including only the first and second divalent units. See, for example, U.S. Pat. No. 10,106,724 (Dams et al.).

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 °F (37.8 °C) to 400 °F (204 °C) although the methods are not limited to hydrocarbon-bearing formations having these conditions. 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 according to the present disclosure 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 compositions described herein are treated with the hydrocarbon-bearing formations. Examples of shut-in times include a few hours (e.g., 1 to 12 hours), about 24 hours, or a few (e.g., 2 to 10) days. After the treatment composition has been allowed to remain in place for the desired time, the solvent 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 methods of treating a hydrocarbon-bearing formation, a pre-flush is used to solubilize or displace brine in a formation before treatment. The fluid may be useful for decreasing the concentration of at least one of the salts present in the brine before 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 before the fluid pre-flush may result in precipitation of salt or the fluorinated polymer while the combination of the treatment composition with the brine after the fluid pre-flush may result in no precipitation.) See, for example, U.S. Pat. No. 8,403,050 (Pope et al.). Examples of fluid proposed as pre-flush fluids include nitrogen, carbon dioxide, methane, toluene, diesel, heptane, octane, condensate, polyol and polyol ether independently having from 2 to 25 carbon atoms, monohydroxy alcohol, ether, or ketone independently having up to four carbon atoms, and combinations of these. The fluid can substantially free of fluorinated surfactants. The term“substantially free of fluorinated surfactants” refers to fluid that may have a fluorinated surfactant 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 fluorinated surfactant may be a fluid that has a fluorinated surfactant 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 fluorinated surfactant includes those that have a weight percent of such polymers as low as 0 weight percent.

In some embodiment of the method of the present disclosure, it can be useful to contact 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 at least partially displaces at least one of the brine or liquid hydrocarbons in the hydrocarbon-bearing formation. The fluid can any of those described above.

However, the compositions of the present disclosure solubilize large quantities of brine, as shown in the Examples, below. Accordingly, in some embodiments of the method of the present disclosure, the method does not include contacting the hydrocarbon-bearing formation with a pre-flush fluid to solubilize or displace at least one of brine or liquid hydrocarbons in the hydrocarbon-bearing formation before contacting the hydrocarbon-bearing formation with the composition. Avoiding the pre-flush step can advantageously reduce the time and expense of carrying out the method of the present disclosure.

In some embodiments of the methods and treated hydrocarbon-bearing formations disclosed herein, the hydrocarbon-bearing formation has at least one fracture. In some embodiments, fractured formations have at least 2, 3, 4, 5, 6, 7, 8, 9, or 10 or more fractures. As used herein, the term "fracture" refers to a fracture that is man-made. In the field, for example, 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 of the methods disclosed herein, wherein treating the formation with the composition provides an increase in at least one of the gas permeability or the liquid permeability of the formation, the formation is a non-fractured formation (i.e., free of man-made fractures made, for example, by hydraulic fracturing). Advantageously, treatment methods disclosed herein typically provide an increase in at least one of the gas permeability or the hydrocarbon liquid permeability of the formation without fracturing the formation.

In some embodiments of the methods and treated hydrocarbon-bearing formations disclosed herein, wherein the hydrocarbon-bearing formation has at least one fracture, the fracture has a plurality of proppants therein. Before delivering the proppants into a fracture, the proppants may be treated with a fluorinated polymer or may be untreated (e.g., may comprise less than 0.1% by weight fluorinated polymer, based on the total weight of the plurality of proppants). In some embodiments, the fluorinated polymer useful in practicing the present disclosure is adsorbed on at least a portion of the plurality of proppants.

Exemplary proppants known in the art include those made of sand (e.g., Ottawa, Brady or Colorado Sands, often referred to as white and brown sands having various ratios), resin-coated sand, sintered bauxite, ceramics (i.e., glasses, crystalline ceramics, glass-ceramics, and combinations thereof), thermoplastics, organic materials (e.g., ground or crushed nut shells, seed shells, fruit pits, and processed wood), and clay. Sand proppants are available, for example, from Badger Mining Corp., Berlin, WI; Borden Chemical, Columbus, OH; and Fairmont Minerals, Chardon, OH. Thermoplastic proppants are available, for example, from the Dow Chemical Company, Midland, MI; and BJ Services, Houston, TX. Clay -based proppants are available, for example, from CarboCeramics, Irving, TX; and Saint-Gobain, Courbevoie, France. Sintered bauxite ceramic proppants are available, for example, from Borovichi Refractories, Borovichi, Russia; 3M Company, St. Paul, MN; CarboCeramics; and Saint Gobain. Glass bubble and bead proppants are available, for example, from Diversified Industries, Sidney, British Columbia, Canada; and 3M Company.

Proppants useful in practicing the present disclosure may have a particle size in a range from 100 micrometers to 3000 micrometers (i.e., about 140 mesh to about 5 mesh (ANSI)) (in some embodiments, in a range from 1000 micrometers to 3000 micrometers, 1000 micrometers to 2000 micrometers, 1000 micrometers to 1700 micrometers (i.e., about 18 mesh to about 12 mesh), 850 micrometers to 1700 micrometers (i.e., about 20 mesh to about 12 mesh), 850 micrometers to 1200 micrometers (i.e., about 20 mesh to about 16 mesh), 600 micrometers to 1200 micrometers (i.e., about 30 mesh to about 16 mesh), 425 micrometers to 850 micrometers (i.e., about 40 to about 20 mesh), or 300 micrometers to 600 micrometers (i.e., about 50 mesh to about 30 mesh).

In some embodiments of methods of treating fractured formations, the proppants form packs within a formation and/or wellbore. Proppants may be selected to be chemically compatible with the solvents and compositions described herein. The term "proppant" as used herein includes fracture proppant materials introducible into the formation as part of a hydraulic fracture treatment and sand control particulate introducible into the wellbore or formation as part of a sand control treatment such as a gravel pack or frac pack.

In some embodiments, methods according to the present disclosure include treating the hydrocarbon-bearing formation with the composition at least one of during fracturing or after fracturing the hydrocarbon-bearing formation. In some of these embodiments, the fracturing fluid, which may contain proppants, may be aqueous (e.g., a brine) or may contain predominantly organic solvent (e.g., an alcohol or a hydrocarbon). In some embodiments, it may be desirable for the fracturing fluid to include contain viscosity enhancing agents (e.g., polymeric viscosifiers), electrolytes, corrosion inhibitors, scale inhibitors, and other such additives that are common to a fracturing fluid. In some embodiments of methods of treating fractured formations, the amount of the composition introduced into the fractured formation is based at least partially on the volume of the fracture(s). The volume of a fracture can be measured using methods that are known in the art (e.g., by pressure transient testing of a fractured well). Typically, when a fracture is created in a hydrocarbon-bearing subterranean formation, the volume of the fracture can be estimated using at least one of the known volume of fracturing fluid or the known amount of proppant used during the fracturing operation. Coil tubing, for example, may be used to deliver the treatment composition to a particular fracture. In some

embodiments, in practicing the methods disclosed herein it may be desirable to isolate the fracture (e.g., with conventional packers) to be treated with the treatment composition.

In some embodiments, wherein the formation treated according to the methods described herein has at least one fracture, the fracture has a conductivity, and after the treatment composition treats at least one of the fracture or at least a portion of the plurality of proppants, the conductivity of the fracture is increased (e.g., by 25, 50, 75, 100, 125, 150, 175, 200, 225, 250, 275, or by 300 percent).

Referring to Fig. 2, 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. Some Embodiments of the Disclosure

In a first embodiment, the present disclosure provides a composition comprising a fluorinated polymer, a first solvent, and a second solvent, wherein the fluorinated polymer comprises:

first divalent units represented by formula:

wherein

Rf represents a fluoroalkyl group having from 1 to 8 carbon atoms or a poly fluoropoly ether group;

each R ¹ is independently hydrogen or methyl;

Q is a bond, -S0 ₂ -N(R)-, or -C(0)-N(R)-, wherein R is alkyl having from 1 to 4 carbon atoms; and

m is an integer from 1 to 11, and

second divalent units, each independently comprising a poly(alkyleneoxy) group,

wherein the first solvent is ethylene glycol, 1,2-propanediol, 1,3-propanediol, or 2,3-butanediol, and wherein the second solvent is a linear monohydroxy alcohol having from 4 to 12 carbon atoms and optionally at least one ether linkage.

In a second embodiment, the present disclosure provides the composition of the first embodiment, wherein the first solvent is 1,2-propanediol.

In a third embodiment, the present disclosure provides the composition of the first or second embodiment, wherein the second solvent is a linear monohydroxy alcohol having from 4 to 10 carbon atoms and optionally at least one ether linkage.

In a fourth embodiment, the present disclosure provides the composition of any one of the first to third embodiments, wherein the second solvent is a linear monohydroxy alcohol having from 5 to 10 carbon atoms and optionally at least one ether linkage.

In a fifth embodiment, the present disclosure provides the composition of the fourth embodiment, wherein the second solvent is 1-pentanol, 1-hexanol, 1-heptanol, 1-octanol, or 2-butoxy ethanol.

In a sixth embodiment, the present disclosure provides the composition of any one of the first to third embodiments, wherein the second solvent is 1 -butanol, 1-pentanol, 1-hexanol, or 2-butoxyethanol.

In a seventh embodiment, the present disclosure provides the composition of any one of the first to sixth embodiments, wherein the first solvent is present in an amount of at least 45, 50, 60, or 70 percent by weight, based on the total weight of the first solvent and the second solvent.

In an eighth embodiment, the present disclosure provides the composition of any one of the first to seventh embodiments, wherein the first and second solvents make up at least 95, 97, 98, 99, or 99.5 percent by weight of the solvent in the composition, or wherein the first and second solvents make up 100 percent by weight of the solvent in the composition.

In a ninth embodiment, the present disclosure provides the composition of any one of the first to eighth embodiments, wherein the fluorinated polymer is present in an amount up to ten percent by weight, based on the total weight of the composition.

In a tenth embodiment, the present disclosure provides the composition of any one of the first to ninth embodiments, wherein the fluorinated polymer is present in an amount ranging from 0.1 to 5 percent by weight, based on the total weight of the composition.

In an eleventh embodiment, the present disclosure provides the composition of any one of the first to tenth embodiments, wherein Q is -S0 ₂ N(R)- and R is methyl or ethyl.

In a twelfth embodiment, the present disclosure provides the composition of any one of the first to eleventh embodiments, wherein Rf represents a fluoroalkyl group having up to 8 or up to 6 carbon atoms.

In a thirteenth embodiment, the present disclosure provides the composition of any one of the first to twelfth embodiments, wherein at least some of the second divalent units are independently represented by formula:

wherein

each R ² is independently hydrogen or methyl;

each R ³ is independently alkyl having up to 4 carbon atoms;

each R ¹⁰ O is independently selected from the group consisting of -CH2CH2O-, -

CH(CH ₃ )CH ₂ 0-, -CH2CH2CH2O-, -CH ₂ CH(CH ₃ )0-, -CH2CH2CH2CH2O-, -

CH(CH ₂ CH ₃ )CH ₂ 0-, -CH ₂ CH(CH ₂ CH ₃ )0-, and -CH ₂ C(CH ₃ ) ₂ 0-; and

each s is independently a value from 5 to 300.

In a fourteenth embodiment, the present disclosure provides the composition of any one of the first to thirteenth embodiments, wherein at least some of the second divalent units are independently represented by formula:

wherein

each R ² is independently hydrogen or methyl;

each R ³ is independently alkyl having up to 4 carbon atoms or hydrogen;

EO represents -CH2CH2O-;

each R ⁴ 0 is independently selected from the group consisting of

-CH(CH ₃ )CH ₂ 0- -CH2CH2CH2O- ,-CH ₂ CH(CH ₃ )0-, -CH2CH2CH2CH2O-, -CH(CH ₂ CH ₃ )CH ₂ 0- -CH ₂ CH(CH ₂ CH ₃ )0- and -CH ₂ C(CH ₃ ) ₂ 0-;

each p is independently a value from 0 to 150; and

each q is independently a value from 0 to 150, wherein p+q is at least 5.

In a fifteenth embodiment, the present disclosure provides the composition of any one of the first to fourteenth embodiments, wherein at least some of the second divalent units are independently represented by formula:

wherein

each R ² is independently hydrogen or methyl;

EO represents -CH2CH2O-;

each R ⁴ 0 is independently selected from the group consisting of

-CH(CH ₃ )CH ₂ 0-, -CH2CH2CH2O-, -CH ₂ CH(CH ₃ )0- -CH ₂ CH ₂ CH ₂ CH ₂ 0-,-CH(CH ₂ CH ₃ )CH ₂ 0-, -CH ₂ CH(CH ₂ CH ₃ )0-, and

-CH ₂ C(CH ₃ ) ₂ 0-;

each r is independently a value from 0 to 150; and

each q is independently a value from 0 to 150, wherein p+q is at least 5. In a sixteenth embodiment, the present disclosure provides the composition of any one of the first to fifteenth embodiments, wherein at least some of the second divalent units comprise a pendant poly(alkyleneoxy) group.

In a seventeenth embodiment, the present disclosure provides the composition of any one of the first to sixteenth embodiments, wherein the second divalent units are present in an amount of at least 30, 40, 50, or 60 percent by weight, based on the total weight of the fluorinated polymer.

In an eighteenth embodiment, the present disclosure provides the composition of any one of the first to seventeenth embodiments, wherein the fluorinated polymer is a nonionic polymer.

In a nineteenth embodiment, the present disclosure provides the composition of any one of the first to seventeenth embodiments, wherein the fluorinated polymer further comprises third divalent units, each of the third divalent units independently comprising a pendant ionic group.

In a twentieth embodiment, the present disclosure provides the composition of the nineteenth embodiment, wherein at least some of the third divalent units are independently represented by formula:

wherein

Q ¹ is selected from the group consisting of -0-, -S-, and -N(R ⁷ )-;

each R ⁷ is independently selected from the group consisting of hydrogen and alkyl having from 1 to 4 carbon atoms;

each R’ is independently hydrogen or methyl;

V is alkylene that is optionally interrupted by at least one ether linkage or amine linkage; Z is selected from the group consisting of -P(0)(OY) ₂ , -0-P(0)(0Y) ₂ , -SO3Y, -O-SO3Y, and -CO2Y ; and

each Y is independently selected from the group consisting of hydrogen and a counter cation.

In a twenty-first embodiment, the present disclosure provides the composition of the nineteenth or twentieth embodiment, wherein at least some of the third divalent units are independently represented by formula:

wherein

Q ¹ is selected from the group consisting of -0-, -S-, and -N(R ⁷ )-;

each R ⁷ is independently selected from the group consisting of hydrogen and alkyl having from 1 to 4 carbon atoms;

each R’ is independently hydrogen or methyl;

V is alkylene that is optionally interrupted by at least one ether linkage or amine linkage; and

Z ¹ is selected from the group consisting of -N(R ⁹ )2, -N(R ⁹ ) ₂ (0), -[N(R ⁸ )3] ⁺ M ^~ ,

-N ⁺ (R ⁸ ) ₂ -(CH ₂ ) _g -S0 ₃ Y ¹ , and -N ⁺ (R ⁸ ) ₂ -(CH ₂ ) _g -C0 ₂ Y ¹ , wherein

each R ⁸ is independently selected from the group consisting of hydrogen and alkyl having from 1 to 6 carbon atoms;

each R ⁹ is independently selected from the group consisting of hydrogen and alkyl having from 1 to 6 carbon atoms, wherein alkyl is optionally substituted by at least one halogen, hydroxyl, alkoxy, nitro, or nitrile group, or two R ⁹ groups may join to form a 5 to 7-membered ring optionally containing at least one O, N, or S and optionally substituted by alkyl having 1 to 6 carbon atoms;

each g is independently an integer from 2 to 6;

M is a counter anion; and

Y ¹ is selected from the group consisting of hydrogen and a free anion.

In a twenty-second embodiment, the present disclosure provides the composition of any one of the first to twenty-first embodiments, wherein the fluorinated polymer further comprises a divalent unit represented by formula:

wherein

each R ⁵ is independently alkyl having from 1 to 30 carbon atoms; and

each R ⁶ is independently hydrogen or methyl.

In a twenty-third embodiment, the present disclosure provides the composition of any one of the first to twenty-second embodiments, wherein the fluorinated polymer has a weight average molecular weight in a range from 1,000 grams per mole to 100,000 grams per mole.

In a twenty-fourth embodiment, the present disclosure provides a method of treating a hydrocarbon-bearing formation, the method comprising contacting the hydrocarbon-bearing formation with the composition of any one of any one of the first to twenty -third embodiments.

In a twenty-fifth embodiment, the present disclosure provides the method of the twenty-fourth embodiment, wherein the hydrocarbon-bearing formation comprises brine, and wherein the composition at least partially solubilizes the brine in the hydrocarbon-bearing formation.

In a twenty-sixth embodiment, the present disclosure provides the method of the twenty-fourth or twenty-fifth embodiment, wherein the method does not comprise contacting the hydrocarbon-bearing formation with a pre-flush fluid to solubilize or displace at least one of brine or liquid hydrocarbons in the hydrocarbon-bearing formation before contacting the hydrocarbon-bearing formation with the composition.

In a twenty-seventh embodiment, the present disclosure provides the method of the twenty-fourth or twenty -fifth embodiment, 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 at least partially displaces at least one of the brine or liquid hydrocarbons in the hydrocarbon-bearing formation.

In a twenty-eighth embodiment, the present disclosure provides the method of any one of the twenty-fourth to twenty-seventh embodiments, wherein the hydrocarbon-bearing formation comprises at least one of limestone, dolomite, sandstone, shale, conglomerate, diatomite, or sand.

In a twenty-ninth embodiment, the present disclosure provides the method of any one of the twenty-fourth to twenty-eighth embodiments, wherein the hydrocarbon-bearing formation has at least one fracture, and wherein the fracture has a plurality of proppants therein.

In a thirtieth embodiment, the present disclosure provides the method of the twenty-ninth embodiment, wherein the plurality of proppants comprises ceramic proppants. In a thirty-first embodiment, the present disclosure provides the method of the thirtieth embodiment, wherein the plurality of proppants comprises bauxite proppants.

In a thirty-second embodiment, the present disclosure provides the method of any one of the twenty-fourth to twenty-eighth embodiments, wherein the method does not include intentionally fracturing the hydrocarbon-bearing formation.

In a thirty-third embodiment, the present disclosure provides the method of any one of the twenty-fourth to twenty-eighth embodiments, wherein the hydrocarbon-bearing formation is free of manmade fractures.

In a thirty-fourth embodiment, the present disclosure provides the method of any one of the twenty-fourth to thirty -third embodiments, 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 thirty-fifth embodiment, the present disclosure provides the method of any one of the twenty- fourth to thirty-fourth embodiments, 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 thirty-sixth embodiment, the present disclosure provides the method of any one of the twenty-fourth to thirty-fifth embodiments, further comprising obtaining (e.g., pumping or producing) hydrocarbons from the wellbore after treating the hydrocarbon-bearing formation with the treatment composition.

In a thirty-seventh embodiment, the present disclosure provides a hydrocarbon-bearing formation treated according to the method of any one of the twenty-fourth to thirty-sixth embodiments.

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 invention. Unless otherwise noted, all parts, percentages, ratios, etc. in the examples and the rest of the specification are by weight.

EXAMPLES

In the following Examples, the Fluorinated Polymer was prepared according to the method described in U.S. Pat. No. 6,664,354, 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 methane sulfonic acid (instead of triflic acid), and 7590 kg of water in Part B, using 15.6 grams of 50/50 mineral spirits/TRIGONOX-21-C50 organic peroxide initiator (tert- butyl peroxy-2-ethylhexanoate obtained from Akzo Nobel, Amhem, The Netherlands) in place of 2,2'-azobisisobutyronitrile in Example 4. Dipropylene glycol monomethyl ether was added after the polymerization and before the batch was stripped. The residual toluene in the Fluorinated Polymer was 0.4% to 0.7% by weight, and the residual dipropylene glycol monomethyl ether in the Fluorinated Polymer was 2% to 3% by weight.

1-Pentanol, famesol, nerol, menthol, geraniol, and nerolidol were obtained from Sigma- Aldrich Corporation, St. Louis, Missouri. Diethylene glycol monomethyl ether, 1,2-propanediol, citronellol, 1- butanol, 2-butoxyethanol, 1-heptanol, 1-octanol, and 1-decanol were obtained from Alfa Aesar, Ward Hill, Mass. 1-Hexanol was obtained from Acros Organics, part of Thermo Fisher Scientific, New Jersey, USA. 2,3-Butanediol and triethylene glycol monomethyl ether were obtained from TCI America, Portland, Oregon. Ethylene glycol was obtained from VWR, Radnor, Penn.

Examples 1 to 3

Fluorinated Polymer (0.2 gram (g)) and first (1 ^st ) and second (2 ^nd ) solvents (9.8 g total amount) were added to a vial to prepare a sample. Brine (0.5 g) having a composition of 37, 156 milligrams per liter (mg/L) sodium ion and 30,900 mg/L calcium ion with chloride as the counterion was added to the vial and shaken by hand. The vial was sealed and placed in an oil bath heated at 135 °C. The vial remained in the bath for 10 minutes. The vial was removed from the bath and visually inspected. The procedure was repeated by adding brine in approximately 0.5-g increments. The samples remained homogeneous throughout the evaluation.

The solvents used for each Example and their amounts based on the total amount of solvent are shown in Table 1 below. Also, the total amount of brine and the weight percent of brine added based on the combined weight of solvents, brine, and Fluorinated Polymer are shown in Table 1, below.

Table 1

Examples 4 to 16

Fluorinated Polymer (0.06 g) and first (1 ^st ) and second (2 ^nd ) solvents (2.94 g total amount) were added to a vial to prepare a sample. Brine (approximately 0.25 g) having the same composition of the brine in Examples 1 to 3 was added to the vial and shaken by hand. The vial was sealed and placed in an oil bath heated at 120 °C. The vial remained in the bath for 5 minutes. The vial was removed from the bath and visually inspected. If the sample was one phase, the brine addition (in approximately 0.25-g increments), shaking, and heating steps were repeated until phase separation was observed in the sample. The solvents used for each Example and their amounts based on the total amount of solvent are shown in Table 2, below. Also, the total amount in wt. % of brine (based on the combined weight of solvents, brine, and Fluorinated Polymer) added before phase separation, and the amount added in which phase separation was first observed are shown in Table 2, below.

Table 2

Mixtures of ethylene glycol (70) and 1-octanol (30) or 1-decanol (30) phase separated when initial amounts of 0.31 g and 0.26 g, respectively, of brine were added.

Examples 17 to 25

Fluorinated Polymer (0.18 g) and first (1 ^st ) and second (2 ^nd ) solvents (2.82 g total amount) were added to a vial to prepare a sample. Brine (approximately 0.25 g) having a composition of 40,000 mg/L sodium ion and 18,250 mg/L calcium ion with chloride as the counterion was added to the vial and shaken by hand. The vial was sealed and placed in an oil bath heated at 150 °C. The vial remained in the bath for 5 minutes. The vial was removed from the bath and visually inspected. If the sample was one phase, the brine addition (in approximately 0.25-g increments), shaking, and heating steps were repeated until phase separation was observed in the sample. The solvents used for each Example and their amounts based on the total amount of solvent are shown in Table 3, below. Also, the total amount in wt. % of brine (based on the combined weight of solvents, brine, and Fluorinated Polymer) added when phase separation was first observed is shown in Table 3, below. For each of Examples 17 to 22, no phase separation was observed when the Examples included 25% brine. Example 19 was foamy at the end of the evaluation.

Table 3

Comparative Examples A to H

Comparative Examples A to H were carried out using the method of Examples 1 to 3 except using the solvents and amounts shown in Table 4, below. The procedure was not repeated because failure (e.g., phase separation or precipitation) was observed after the first addition of brine. The solvents used for each Example and their amounts based on the total amount of solvent are shown in Table 4, below. Also, the total amount in wt. % of brine (based on the combined weight of solvents, brine, and

Fluorinated Polymer) added when phase separation or precipitation was first observed is shown in Table 4, below. Table 4

Comparative Examples I to K

Comparative Examples I to K were carried out using the method of Examples 4 to 16 except using the solvents and amounts (based on the total amount of solvent) shown in Table 5, below, and heating in an oil bath at a temperature of 135 °C. The procedure was not repeated because failure (e.g., phase separation or precipitation) was observed after the first addition of brine, the wt. % (based on the combined weight of solvents, brine, and Fluorinated Polymer) of which is shown in Table 5, below. Table 5

Comparative Examples I to K

Comparative Examples I to K were carried out using the method of Examples 4 to 16 except using the solvents and amounts (based on the total amount of solvent) shown in Table 5, below, and heating in an oil bath at a temperature of 135 °C. The procedure was not repeated because failure (e.g., phase separation or precipitation) was observed after the first addition of brine, the wt. % (based on the combined weight of solvents, brine, and Fluorinated Polymer) of which is shown in Table 5, below. Table 5

Comparative Examples L to Q and Illustrative Examples AA to 00

Comparative Examples L to Q and Illustrative Examples AA to FF were carried out using the method of Examples 4 to 16 with the following modifications. The first solvent was 2-butoxyethanol in a 70:30 ratio with second solvent 1-butanol, 1-pentanol, 1-hexanol, 1-heptanol, 1-octanol, and 1-deacnaol to provide Comparative Examples L to Q, respectively. The procedure was not repeated because precipitation was observed after the first addition of brine (0.23 g to 0.27 g, 7.1 wt. % to 8.2 wt. %). Illustrative Examples AA to FF were carried out using the method of Examples 4 to 16 with the following modifications. The first solvent was triethylene glycol monomethyl ether in a 70:30 ratio with second solvent 1 -butanol, 1-pentanol, 1-hexanol, 1-heptanol, 1-octanol, and 1-deacnaol to provide Illustrative Examples AA to FF, respectively. The procedure was not repeated because precipitation was observed after the first addition of brine (0.25 g to 0.27 g, 7.7 wt. % to 8.2 wt. %). Illustrative Examples GG to OO were carried out using the method of Examples 4 to 16 with the following modifications. The first solvent was diethylene glycol monomethyl ether, 1,3-butanediol, or 1,4-butanediol in a 70:30 ratio with second solvent 1 -butanol, 1-pentanol, and 1-hexanol to provide Illustrative Examples GG to OO, respectively. The procedure was not repeated because precipitation was observed after the first addition of brine (0.25 g to 0.29 g, 7.7 wt. % to 8.8 wt. %).

Comparative Examples R to Z

Comparative Examples R to Z were carried out using the method of Examples 17 to 25 with the following modifications. The first solvent was 2-butoxyethanol in a 70:30 ratio with second solvent 1- butanol, 1-pentanol, 1-hexanol, citronellol, geraniol, nerol, famesol, nerolidol, and menthol to provide Comparative Examples Rto Z, respectively. The procedure was not repeated because precipitation was observed after the first addition of brine (7.7 wt. %).

Core flood evaluations on core samples can be carried out using core flood apparatus 200 that can be used as shown in Fig. 1. 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 accumulators 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 °C and then wrapped in aluminum foil and heat shrink tubing. Referring again to Fig. 1, 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 10 ⁷ 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 10 ⁴ to 6.9 x 10 ⁴ 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 2.1 mL 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 10 ⁶ 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 10 ⁶ 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 including the fluorinated polymer and first and second solvents 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 10 ⁶ 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 invention is not to be unduly limited to the illustrative embodiments set forth herein.