Methods of using ionic liquids as paraffin inhibitors, pour point depressants and cold flow improvers

1. A method of modifying the pour point or cold flow of crude oil or gas, or reducing the deposition of paraffin from crude oil or gas, during production of the crude oil or gas from a subterranean reservoir, the method comprising:

(a) adding to the produced crude oil or gas in the subterranean reservoir an ionic liquid of the formula:

A + X −   (I)

wherein:

A is or contains nitrogen; and

X is an anion selected from the group consisting of anionic copolymers of alpha olefins and maleic anhydride, esters, amides, imides or derivatives thereof; anionic acrylamido-methyl propane sulfonate/acrylic acid copolymers; anionic homopolymers, copolymers and terpolymers of one or more acrylates, methacrylates and acrylamides, optionally copolymerized with one or more ethylenically unsaturated monomers; anionic phosphated maleic copolymers; an anionic homo or copolymer of an oxirane or methyloxirane; anionic copolymers of ethylene and vinyl acetate; and mixtures thereof or a methyl oxirane; and

(b) retarding, delaying, minimizing, reducing, inhibiting or preventing phase separation of paraffin wax formed in the crude oil or gas by dispersing the paraffin wax in the crude oil or gas containing the ionic liquid in the subterranean reservoir; or enhancing fluidity of the crude oil or gas while flowing the crude oil or gas containing the ionic liquid from the subterranean reservoir through a conduit; or depressing the pour point of the crude oil or gas in the subterranean reservoir when the crude oil or gas contains paraffin wax and further contains the ionic liquid.

2. The method of claim 1 , wherein anion X is selected from the group consisting of anionic acrylamido-methyl propane sulfonate/acrylic acid copolymers; anionic homopolymers, copolymers and terpolymers of one or more acrylates, methacylates and acrylamides, optionally copolymerized with one or more ethylenically unsaturated monomers; anionic ethylene vinyl acetate copolymers; anionic phosphated maleic copolymers and mixture thereof or a zwitterion.

3. A method of modifying the pour point or cold flow of crude oil or reducing the deposition of paraffin from the crude oil during production of the crude oil from an underground reservoir, the method comprising:

(a) adding to the crude oil in the underground reservoir an ionic liquid of the formula:

R 1 R 2 R 3 A + R 8 A + R 5 R 6 R 7 X −   (III)

wherein:

each A in formula (III) is or contains nitrogen; and

X is an anion selected from the group consisting of halides; hydroxyl; carbonates; alkyl carbonates; bicarbonates; carboxylates; hydroxycarboxylates; sulfonates; sulfates; bisulfites; thiocyanates; dithiocarbonates; trithiocarbonates; carbamates; dithiocarbamates; xanthates; sulfides; polysulfides; alkoxides; anionic urea; anionic alkyl substituted phosphines; anionic amino fatty acids; anionic alkoxylated fatty acids; anionic acrylamido-methyl propane sulfonate/acrylic acid copolymers; anionic phosphated maleic copolymers; anionic metal complexes; sulfur or silicon containing anions; anionic phosphate esters; anionic thiophosphate esters; anionic phosphonate esters; anionic thiophosphonate esters; anionic thiols; anionic natural products; anionic phenols; anionic phenol resins; anionic copolymers of alpha olefins and maleic anhydride, esters, amides, imides or derivatives thereof; anionic alkyl substituted phosphines; and anionic homopolymers, copolymers and terpolymers of one or more acrylates, methacrylates acrylamides and acids, optionally copolymerized with one or more ethylenically unsaturated monomers; anionic homo and copolymers of oxirane and/or methyloxirane; anionic copolymers of olefins and vinyl acetate; and mixtures thereof; and further wherein R 1 , R 2 , R 3 , R 4 , R 5 , R 6 and R 7 are independently selected from the group consisting of hydrogen; benzyl; alkylbenzyl, or oxyalkyl; a straight or branched alkyl group, an alkylbenzyl group, an arylalkyl group, a straight or branched chain alkenyl group, a hydroxyalkyl group or a hydroxyalkylbenzyl group; and a polyoxyalkylene group; and R 8 is a straight or branched alkylene group, an alkylene oxyalkylene, or an alkylene polyoxyalkylene or a zwitterion; and further wherein R groups may be joined to form a heterocyclic nitrogen, sulfur or phosphorus containing ring; and

(b) retarding, delaying, minimizing, reducing, inhibiting or preventing phase separation of paraffin wax formed in the crude oil by dispersing the paraffin wax in the crude oil containing the ionic liquid in the subterranean reservoir; or enhancing fluidity of the crude oil while flowing the crude oil containing the ionic liquid from the subterranean reservoir through a conduit; or depressing the pour point of the crude oil in the subterranean reservoir when the crude oil contains paraffin wax and further contains the ionic liquid.

4. The method of claim 3 , wherein R 1 , R 2 , R 3 , R 4 , R 5 , R 6 and R 7 are independently selected from the group consisting of hydrogen; benzyl; oxyalkyl; a straight or branched C 1-30 alkyl group; a C 7-30 alkylbenzyl group; a C 7-30 arylalkyl group; a straight or branched C 3-30 alkenyl group; a C 1-30 hydroxyalkyl group; a C 7-30 hydroxyalkylbenzyl group; and a polyoxyalkylene group and further wherein R groups may be joined to form a heterocyclic nitrogen or phosphorus containing ring; and R 8 is a straight or branched C 1-30 alkylene, an alkylene oxyalkylene, or an alkylene polyoxyalkylene.

5. The method of claim 4 , wherein X is an anionic oxirane or methyloxirane homo or copolymer containing (CH 2 CH 2 O) x CH 2 CH(CH 3 )O) 4 where x and y are independently selected from 1 to 1500 and mixtures thereof; an anionic ethylene vinyl copolymer; or an anionic olefin and maleic acid or anhydride optionally esterified with an alcohol.

6. The method of claim 4 , wherein X of (I), (II) or (III) is a hydroxide, halide, anionic bicarbonate, anionic carbonate, anionic alkyl carbonate, anionic alkoxide or anionic carboxylate or a combination thereof.

7. The method of claim 3 , wherein X is selected from the group consisting of anionic condensation polymers of alkylene oxides and glycols, anionic ethylene oxide/propylene oxide copolymers, arylsulfonates, anionic ureas, anionic thioureas, anionic polyether polyols, anionic polyethers, anionic polyol esters, anionic polyesters, anionic polyglycol esters, anionic polyurethanes, anionic oxyalkylated polymers condensation polymers of di-propylene glycol as well as trimethylol propane; anionic phenolic polymers, anionic alkyl substituted phenol formaldehyde resins, anionic oxyalkylated phenol formaldehyde resins, anionic alkoxylated epoxy resins, anionic diepoxides, anionic melamine acid colloids, alkylaryl sulfonates, alkylarylsulfonate, anionic amine salts, anionic aminomethylated polyacrylamide; anionic condensates of o-toluidine and formaldehyde; anionic polyalkylene glycols; sulfonated glycerides; sulfonated oils; anionic acetylated castor oils; anionic oxyalkylated ether sulfate salts, anionic copolymers of olefins and vinyl acetate; and anionic oxirane or methyloxirane polymers and mixtures thereof.

8. The method of claim 3 , wherein X is selected from the group consisting of anionic ethylene vinyl acetate copolymers, anionic maleic olefin alkyl esters, anionic acrylate esters, anionic methacrylic esters, copolymers of maleic anhydride and α,β-unsaturated compounds, optionally reacted with primary monoalkylamines and/or aliphatic alcohols, anionic products of the reaction of alkenylspirobislactones with amines; anionic products of the reaction of α,β-unsaturated dicarboxylic anhydrides, α,β-unsaturated compounds and polyoxyalkylene ethers; anionic phenol formaldehyde resins or a mixture thereof.

9. The method of claim 3 , wherein X is selected from the group consisting of anionic ethylene-vinyl acetate copolymers, anionic alpha olefin-maleic anhydride copolymer esters and anionic phenol formaldehyde resins and mixtures thereof.

10. The method of claim 1 , wherein X is the anion of an ethylene-vinyl acetate copolymer of the structure:

wherein x is from 1 to about 100 and y is from about 1 to about 100.

11. The method of claim 1 , wherein X is the anion of an alpha olefin-maleic anhydride copolymer ester of the structure:

wherein R is a C 18 to C 30 alkyl group and R′ is —H or C 18 to C 28 alkyl group.

12. The method of claim 2 , wherein X is the anion of a phenol aldehyde resin of the structure:

(a)

wherein R is —H or a C 1-20 linear or branched alkyl and n is greater than 2; or

(b)

where R 5 is a C 1-20 linear or branched alkyl, R 6 is different from R 5 and is H or a linear or branched C 1-20 alkyl, and n and m are greater than 1.

13. The method of claim 12 , wherein R 5 is a C 7-16 linear or branched alkyl and R 6 is a C 1-6 linear or branched alkyl.

14. The method of claim 1 , wherein the ionic liquid is a component of a treatment composition comprising the ionic liquid and a second agent selected from the group consisting of paraffin inhibitors, pour point depressants and cold flow improvers, the paraffin inhibitors, pour point depressants and cold flow improvers not being an ionic liquid.

15. The method of claim 14 , wherein X is an anionic oxirane or methyloxirane homo or copolymer containing (CH 2 CH 2 O) x CH 2 CH(CH 3 )O) 4 where x and y are independently selected from 1 to 1500 and mixtures thereof; an anionic ethylene vinyl copolymer; or an anionic olefin and maleic acid or anhydride optionally esterified with an alcohol.

16. The method of claim 3 , wherein the ionic liquid is added to the crude oil by either (a) injecting a slug of the ionic liquid into the well penetrating the subterranean reservoir; (b) introducing the ionic liquid through a capillary string; or (c) introducing the ionic liquid through an annulus of a downpipe in communication with the subterranean reservoir.

17. The method of claim 1 , wherein the ionic liquid is added to the crude oil after the crude oil emerges from the subterranean reservoir.

18. The method of claim 1 , wherein A is a cation selected from the group consisting of dicocodimethyl ammonium, ditallowdimethyl ammonium, benzyltrimethylammonium, dodecyl trimethylammonium, di-hydrogenated tallow dimethylammonium, cocodialkylammonium, tallowtrimethyl ammonium, cocotrialkyl ammonium cocodialkylammonium hydrogenated tallow trimethyl ammonium and oxydiethylene bis(cocodimethylammonium).