Use of polyampholytes to enhance oil and/or gas recovery

Claim 1

A method of recovering oil and/or gas from a subterranean formation which is penetrated by a well bore, and for reducing the concomitant production of reservoir water therefrom comprising injecting into said formation through said well bore an aqueous treating solution or emulsion containing a polyampholyte, having an intrinsic viscosity greater than 10 dl/g in 1.0M sodium chloride, prepared from: (i) 40 to 90%, by weight, of at least one anionic-containing monomer of the formula: ##STR5## wherein R, which may be the same or different, is hydrogen, a phenyl or an alkyl group of from 1 to 3 carbon atoms, R 1 is a straight or branched chain of from 0 to 12 carbon atoms, X is --NHCH 2 C(CH 3 ) 2 SO 3 Y or OY, and Y is hydrogen or an alkali or alkaline earth metal; (ii) 0.5 to 60%, by weight, of at least one cationic-containing monomer selected from the group consisting of: diethyl diallyl ammonium chloride and dimethyl diallyl ammonium chloride; and (iii) 1.5 to 58.5%, by weight, of at least one non-ionic monomer selected from the group consisting of acrylonitrile, vinyl acetate, butadiene, vinyl pyridine, methacrylate, styrene and monomers of the formula: ##STR6## wherein R 6 is hydrogen, a phenyl or an alkyl group of from 1 to 3 carbon atoms, and R 2 , which may be the same or different, is a hydrogen, or an alkyl group of from 1 to 3 carbon atoms, then terminating the injection of said treating solution and thereafter placing the treated well in production.

Claim 2

A method of recovering oil and/or gas from a subterranean formation which is penetrated by a well bore, and for reducing the concomitant production of reservoir water therefrom comprising injecting into said formation through said well bore an aqueous treating solution or emulsion containing a polyampholyte, having an intrinsic viscosity greater than 10 dl/g in 1.0M sodium chloride, prepared from: (i) 40 to 90%, by weight, of at least one anionic-containing monomer of the formula: ##STR5## wherein R, which may be the same or different, is hydrogen, a phenyl or an alkyl group of from 1 to 3 carbon atoms, R 1 is a straight or branched chain of from 0 to 12 carbon atoms, X is --NHCH 2 C(CH 3 ) 2 SO 3 Y or OY, and Y is hydrogen or an alkali or alkaline earth metal; (ii) 0.5 to 60%, by weight, of at least one cationic-containing monomer selected from the group consisting of: diethyl diallyl ammonium chloride and dimethyl diallyl ammonium chloride; and (iii) 1.5 to 58.5%, by weight, of at least one non-ionic monomer selected from the group consisting of acrylonitrile, vinyl acetate, butadiene, vinyl pyridine, methacrylate, styrene and monomers of the formula: ##STR6## wherein R 6 is hydrogen, a phenyl or an alkyl group of from 1 to 3 carbon atoms, and R 2 , which may be the same or different, is a hydrogen, or an alkyl group of from 1 to 3 carbon atoms, then terminating the injection of said treating solution and thereafter placing the treated well in production.

Claim 5

A method of recoverng oil from a subterranean formation which is penetrated by an injection well bore, and for reducing the concomitant production of reservoir water therefrom, comprising injecting into said formation through said injection well bore an aqueous treating solution or emulsion containing a polyampholyte, having an intrinsic viscosity greater than 10 dl/g in 1.0M sodium chloride, prepared from: (i) 40 to 90%, by weight, of at least one anionic-containing monomer of the formula: ##STR7## wherein R, which may be the same or different, is hydrogen, a phenyl or an alkyl group of from 1 to 3 carbon atoms, R 1 is a straight or branched chain of from 0 to 12 carbon atoms, X is --NHCH 2 C(CH 3 ) 2 SO 3 Y or OY, and Y is hydrogen or an alkali or alkaline earth metal; (ii) 0.5 to 60%, by weight, of at least one cationic-containing monomer selected from the group consisting of: diethyl diallyl ammonium chloride and dimethyl diallyl ammonium chloride; and (iii) 1.5 to 58.5%, by weight, of at least one non-ionic monomer selected from the group consisting of acrylonitrile, vinyl acetate, butadiene, vinyl pyridine, methacrylate, styrene and monomers of the formula: ##STR8## wherein R 6 is hydrogen, a phenyl or an alkyl group of from 1 to 3 carbon atoms, and R 2 , which may be the same or different, is a hydrogen, or an alkyl group of from 1 to 3 carbon atoms, and then injecting water into said injection well bore, thereby producing oil from an adjacent producing well bore.

Claim 6

A method of recoverng oil from a subterranean formation which is penetrated by an injection well bore, and for reducing the concomitant production of reservoir water therefrom, comprising injecting into said formation through said injection well bore an aqueous treating solution or emulsion containing a polyampholyte, having an intrinsic viscosity greater than 10 dl/g in 1.0M sodium chloride, prepared from: (i) 40 to 90%, by weight, of at least one anionic-containing monomer of the formula: ##STR7## wherein R, which may be the same or different, is hydrogen, a phenyl or an alkyl group of from 1 to 3 carbon atoms, R 1 is a straight or branched chain of from 0 to 12 carbon atoms, X is --NHCH 2 C(CH 3 ) 2 SO 3 Y or OY, and Y is hydrogen or an alkali or alkaline earth metal; (ii) 0.5 to 60%, by weight, of at least one cationic-containing monomer selected from the group consisting of: diethyl diallyl ammonium chloride and dimethyl diallyl ammonium chloride; and (iii) 1.5 to 58.5%, by weight, of at least one non-ionic monomer selected from the group consisting of acrylonitrile, vinyl acetate, butadiene, vinyl pyridine, methacrylate, styrene and monomers of the formula: ##STR8## wherein R 6 is hydrogen, a phenyl or an alkyl group of from 1 to 3 carbon atoms, and R 2 , which may be the same or different, is a hydrogen, or an alkyl group of from 1 to 3 carbon atoms, and then injecting water into said injection well bore, thereby producing oil from an adjacent producing well bore.