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1. (WO2018015222) PROCESS
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Claims

1. A process for reducing the permeability to water of a thief zone of a porous and permeable subterranean petroleum reservoir, said process comprising:

injecting a composition comprising a dispersion of betainised crosslinked polymeric microparticles in an aqueous fluid down a well and into a thief zone,

wherein the betainised crosslinked polymeric microparticles have a transition temperature which is at or below the maximum temperature encountered in the thief zone and greater than the maximum temperature encountered in the well, and

wherein the betainised crosslinked polymeric microparticles are solvated by water and expand in size in the thief zone when they encounter a temperature at or greater than the transition temperature so as to reduce the permeability of the thief zone to water.

2. A process for recovering hydrocarbon fluids from a porous and permeable subterranean petroleum reservoir comprising at least one higher permeability layer of reservoir rock and at least one lower permeability layer of reservoir rock that are penetrated by at least one injection well and at least one production well, the process comprising:

i)■ injecting into the higher permeability layer of reservoir rock a composition comprising betainised crosslinked polymeric microparticles dispersed in an aqueous fluid wherein the higher permeability layer has a region between the injection well and production well having a temperature at or above the transition temperature of the betainised crosslinked microparticles;

ii) propagating said composition through the higher permeability layer until the composition reaches the region of the higher permeability layer having a temperature at or above the transition temperature such that betainised crosslinked microparticles become solvated and expand in size thereby reducing the permeability of the higher permeability layer of the reservoir and diverting subsequently injected aqueous fluid into the lower permeability layer of the reservoir; and

iii) recovering hydrocarbon fluids from said at least one production well.

3. A process according to Claim 2, wherein the higher permeability layer(s) of reservoir rock has a permeability at least 50% greater than the permeability of the lower

permeability layer(s) of reservoir rock.

4. A process according Claims 2 or 3, wherein the composition comprising betainised microparticles is injected into the injection well at a temperature in the range of 4 to 30 °C and the transition temperature of the betainised microparticles is in the range of 20 °C to 120 °C with the proviso that the transition temperature is greater than the injection temperature.

5. A process according to any one of the preceding claims, wherein the composition comprising betainised microparticles is injected in a pore volume amount in the range of

0.05 to 1 , preferably 0.2 to 0.5.

6. A process according to any one of the preceding claims, wherein the initial average particle diameter of the betainised microparticles is in the range of 0.1 to 1 μηι and the average particle diameter of the expanded betainised microparticles is in the range of 1 to 10 microns.

' 7. A method for preparing betainised microparticles, said method comprising:

reacting precursor polymeric microparticles comprising crosslinked polymer chains having pendant groups comprising a betainisable functional group with a betainising reagent to convert at least a portion of the betainisable functional groups to betainised functional groups thereby forming betainised microparticles comprising crosslinked polymer chains having pendant groups comprising a betainised functional group and optionally having pendant groups comprising an unreacted betainisable functional group.

8. A method according to Claim 7, wherein the precursor polymeric microparticles are reacted with a betainising reagent selected from sulfobetainising, carboxybetainising, phosphobetainising, phosphonobetainising and sulfabetainising reagents to form betainised microparticles in which at least a portion of the betainisable functional groups are converted to betainised functional groups.

9. A method according to any one of Claims 7 to 8, wherein the precursor

microparticles are prepared by emulsion polymerization or dispersion polymerization of a mixture of monomers comprising:

(a) monomers having betainisable functional groups;

(b) crosslinking monomers; and

(c) optionally, hydrophobic comonomers that do not contain a betainisable functional group.

10. A method according to Claim 9, wherein the monomers having betainisable functional groups are selected from the group consisting of dialkylaminoalkyl acrylates; dialkylaminoalkyl alkacrylates; dialkylaminoalkyl acrylamides; dialkylaminoalkyl alkacrylamides; vinylaryldialkylamines; and vinyl-N-heterocyclic amines.

11. A method according to Claim 10, wherein the monomers having betainisable functional groups are vinyl-N-heterocyclic amines and the resulting precursor

microparticles have structural units with pendant N-heterocyclic amine rings that are reacted with the betainising reagent to form betainised N-heterocyclic ammonium rings.

12. A method according to Claim 10, wherein the monomers having betainisable functional groups are dialkylaminoalkyl acrylates and alkacrylates of general formula (I):

[H2C=C(R1)C02R2NR3R4]

wherein R1 is selected from hydrogen and methyl;

R is a straight chain alkylene moiety having from 2 to 10 carbon atoms or a branched chain alkylene moiety having a main chain having from 2 to 10 carbons atoms and at least one branched chain having from 2 to 10 carbon atoms with the proviso that the straight or branched chain alkylene moiety is optionally substituted by methyl; and

R3 and R4 are independently selected from methyl, ethyl, n-propyl and isopropyl, or N, R3 and R4 together form an N-heterocyclic amine ring, optionally, including an oxygen heteroatom.

13. A method according to Claim 10, wherein the monomers having betainisable functional groups are dialkylaminoalkyl acrylamides and alkacrylamides of the formula (II):

[H2C=C(R1)CONHR2NR3R4]

wherein R1, R2, R3 and R4 are as defined in Claim 12.

14. A method according to Claim 10, wherein the monomers having betainisable functional groups are vinylbenzyldialkylamines of the general formula (III):

[H2C=C(R1)C6H4R2NR3R4]

wherein R1, R2, R3 and R4 are as defined in Claim 12 or are vinylbenzyldialkylamines analogues of those of general formula (III) in which the benzyl group has from one to three substituents selected from methyl, ethyl, halogen, alkoxy and nitro groups.

15. A method according to any one of Claims 9 to 14, wherein the crosslinking monomer comprises from 0.1 to 10 mol%, preferably 0.5 to 3 mol% of the mixture of monomers used to prepare the precursor microparticles.

16. A method according to any one of Claims 9 to 15, wherein the crosslinking monomers are selected from diacrylamides and methacrylamides of diamines such as the diacrylamide or dimethacrylamide of piperazine or diacrylamide or dimethacrylamide of methylenediamine; methacrylate esters of di, tri, tetra hydroxy compounds including ethyleneglycol dimethacrylate, polyethyleneglycol dimethacrylate, trimethylolpropane trimethacrylate, and the like; divinylbenzene, 1,3-diisopropenylbenzene, and the like; the vinyl or allyl esters of di or trifunctional acids; and, diallylamine, triallylamine, divinyl sulfone, diethyleneglycol diallyl ether, and the like.

17. A method according to any one of Claims 9 to 16, wherein the hydrophobic comonomers are selected from benzyl methacrylate, benzyl acrylate, benzyl acrylamide, benzyl methacrylamide, n-butyl methacrylate, n-butyl acrylate, n-butyl acrylamide, n-butyl methacrylamide, and the like; and styrenic monomers substituted with branched alkyl, straight chain alkyl or aryl groups and comprise up to 50 mol% of the mixture of monomers used to prepare the precursor microparticles.

18. A method according to any one of Claims 7 to 17, wherein the betainisation reagent is of general formula V:

XRA"M+

wherein X is a halogen selected from F, CI, Br and I, preferably, CI and Br;

R is a hydrocarbylene group having up to 30 carbon atoms wherein the hydrocarbylene group may be selected from: branched or unbranched alkylene groups; arylene groups; alkarylene groups (an alkyl substituted arylene group wherein the alkyl substituent may be branched or unbranched); and arylalkylene groups (an aryl substituted alkylene group

where the alkylene group may be branched or unbranched); and wherein the alkylene, arylene, alkarylene or arylalkylene groups may be optionally substituted with functional groups selected from hydroxyl, ether, ester, amide, and the like;

A" is an anionic functional group selected from S03" (sulfonate), P03~(phosphonate), OP03" (phosphate), C03" (carboxylate) and OS03" (ether sulfonate; also referred to as sulfate) functional groups, preferably, S03" (sulfonate); and

M+ is selected from H+, Group IA metal cations and ammonium cations.

19. A method according to Claim 18, wherein the betainisation reagent is a betainisation reagent having a halide leaving group of general formula Va:

XCH2(CH2)nCH2A-M+

wherein X, A" and M+ are as defined above; and

n is an integer in the range of 0 to 20, preferably 0 to 10, in particular, 0 to 3.

20. A method according to any one of Claims 7 to 17 wherein the betainising reagent is a cyclic betainising reagent selected from the group consisting of sultones; lactones;

dioxaphospholane oxides; dioxathiolane dioxides; and dioxathiane dioxides.

21. Betainised microparticles comprising crosslinked polymer chains having pendant groups comprising betainised functional groups and, optionally, pendant groups

comprising unreacted betainisable functional groups wherein the betainised functional groups are present in the microparticles in an amount of from 20 to 100%, preferably from 50 to 95%, based on the total amount of betainised and unreacted betainisable functional groups.

22. Betainised microparticles according to Claim 21 , wherein the microparticles are selected from sulfobetainised microparticles, carboxybetainised microparticles,

phosphobetainised microparticles, phosphonobetainised microparticles and sulfabetainised microparticles, preferably selected from sulfobetainised microparticles and sulfabetainised microparticles.

23. Betainised microparticles according to Claim 22, wherein the betainised

microparticles comprise betainised groups selected from: (2-sulfoethyl)-ammonium betaine groups, (3-sulfopropyl)-ammonium betaine groups, (4-sulfobutyl)-ammonium betaine groups, (2-carboxyethyl)-ammonium betaine groups, (3-carboxypropyl)-ammonium betaine groups, (4-carboxybutyl)-ammonium betaine groups, (2-

phosphoethyl)-ammonium betaine groups, (3-phosphopropyl)-ammonium betaine groups, (4-phosphobutyl)-ammonium betaine groups, (2-phosphonoethyl)-ammonium betaine groups, (3-phosphonopropyl)-ammonium betaine groups, (4-phosphonobutyl)-amnionium betaine groups, (2-sulfaethyl)-ammonium betaine groups, (3-sulfapropyl)-ammonium betaine groups, and (4-sulfabutyl)-ammonium betaine groups.

24. A composition comprising a dispersion of betainised microparticles in an aqueous fluid wherein the betainised microparticles are as defined in any of Claims 21 to 23.

25. A composition according to Claim 24, wherein the composition comprises from 0.01 to 20 % by weight, preferably from 0.01 to 10 % by weight, more preferably from 0.02 to 5 % by weight, and most preferably from 0.05 to 3 % by weight of the betainised

microparticles based on the total weight of the composition.

26. A composition according to Claim 24 or Claim 25 wherein the aqueous fluid has a total dissolved solids (TDS) content in the range of 200 to 250,000 mg/L, preferably, in the range of 500 to 50,000 mg/L, more preferably, 1500 to 35,000 mg/L.

27. A composition according to Claim 26, wherein the aqueous fluid is selected from seawater, estuarine water, brackish water, lake water, river water, desalinated water, produced water, aquifer water or mixtures thereof, preferably seawater.