US4455240A — Ampholytic polymers for use as filtration control…

Claim 1

Independent Claim 178 words

An aqueous drilling fluid comprising: (a) an aqueous clay dispersion; and (b) a water loss reducing amount of a carboxylic functional polyampholyte, or the salt thereof, having an intrinsic viscosity of at least 0.5 dl/g, prepared from: (i) at least one carboxylic functional monomer; of the formula: ##STR5## wherein R is hydrogen, a phenyl group or an alkyl group of from 1 to 3 carbon atoms, R 1 is a branched or straight chain of from 0 to 12 carbon atoms, and X is hydrogen or an alkali or alkaline earth metal (ii) at least one cationic-containing monomer containing an ion selected from the group consisting of a quaternary ammonium, phosphonium or sulfonium having one of the following structures: ##STR6## wherein R 3 is a phenyl or an alkyl group of from 1 to 3 carbon atoms, R 4 is a hydrogen or an alkyl group of from 1 to 3 carbon atoms, R 5 is a straight or branched chain of from 1 to 12 carbon atoms, and X is an anion; and (iii) optionally, non-ionic monomer.

Claim 2

Dependent Claim 178 words

An aqueous drilling fluid comprising: (a) an aqueous clay dispersion; and (b) a water loss reducing amount of a carboxylic functional polyampholyte, or the salt thereof, having an intrinsic viscosity of at least 0.5 dl/g, prepared from: (i) at least one carboxylic functional monomer; of the formula: ##STR5## wherein R is hydrogen, a phenyl group or an alkyl group of from 1 to 3 carbon atoms, R 1 is a branched or straight chain of from 0 to 12 carbon atoms, and X is hydrogen or an alkali or alkaline earth metal (ii) at least one cationic-containing monomer containing an ion selected from the group consisting of a quaternary ammonium, phosphonium or sulfonium having one of the following structures: ##STR6## wherein R 3 is a phenyl or an alkyl group of from 1 to 3 carbon atoms, R 4 is a hydrogen or an alkyl group of from 1 to 3 carbon atoms, R 5 is a straight or branched chain of from 1 to 12 carbon atoms, and X is an anion; and (iii) optionally, non-ionic monomer.

Claim 3

Dependent Claim 45 words

The aqueous drilling fluid of claim 1, wherein said polyampholyte is prepared from (i) 5 to 90%, by weight, of said carboxylic functional monomer; (ii) 0.5 to 85%, by weight, of said cationic-containing monomer; and (iii) 0 to 85%, by weight, of said non-ionic monomer.

Claim 4

Dependent Claim 45 words

The aqueous drilling fluid of claim 2, wherein said polyampholyte is prepared from: (i) 32.5 to 85%, by weight, of said carboxylic functional monomer; (ii) 1.5 to 40%, by weight, of said cationic-containing monomer; and (iii) 5 to 65%, by weight, of said non-ionic monomer.

Claim 5

Dependent Claim 57 words

The aqueous drilling fluid of claim 1, wherein said carboxylic functional monomer is acrylic acid; said non-ionic monomer is selected from the group consisting of acrylamide, methacrylamide and N,N-dimethylacrylamide; and said cationic-containing monomer is selected from the group consisting of diethyldiallyl ammonium chloride, dimethyldiallyl ammonium chloride, methacryloyloxy ethyl trimethyl ammonium methylsulfate and methacrylamido propyl trimethyl ammonium chloride.

Claim 6

Dependent Claim 200 words

The aqueous drilling fluid of claim 1, wherein said carboxylic functional polyampholyte is a terpolymer prepared from: (i) a carboxylic functional monomer of the formula: ##STR7## wherein R is hydrogen, a phenyl or an alkyl group of from 1 to 3 carbon atoms, R 1 is a branched or straight chain of from 0 to 12 carbon atoms, and X is hydrogen or an alkali or alkaline earth metal; (ii) a monomer 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 (iii) a cationic-containing monomer containing an an ion selected from the group consisting of a quaternary ammonium, phosphonium or sulfonium having one of the following structures: ##STR9## wherein R 3 is a phenyl or an alkyl group of from 1 to 3 carbon atoms, R 4 is a hydrogen or an alkyl group of from 1 to 3 carbon atoms, R 5 is a straight or branched chain of from 1 to 12 carbon atoms, and X is an anion.

Claim 7

Dependent Claim 22 words

The aqueous drilling fluid of claim 1, wherein at least 0.125 pound of polyampholyte is used per barrel of aqueous clay dispersions.

Claim 8

Dependent Claim 19 words

The aqueous drilling fluid of claim 1, wherein said polyampholyte has an intrinsic viscosity of 0.5 to 4.5 dl/g.

Claim 9

Independent Claim 201 words

A method of drilling a well in a subterranean formation comprising circulating into the well, during drilling, an aqueous drilling fluid, the improvement wherein said aqueous drilling fluid comprises: (a) an aqueous clay dispersion; and (b) a water loss reducing amount of a carboxylic functional polyampholyte, or its salt, having an intrinsic viscosity of at least 0.5 dl/g, prepared from: (i) at least one carboxylic functional monomer of the formula: ##STR10## wherein R is hydrogen, a phenyl group or an alkyl group of from 1 to 3 carbon atoms, R 1 is a branched or straight chain of from 0 to 12 carbon atoms, and X is hydrogen or an alkali or alkaline earth metal (ii) at least one cationic-containing monomer containing an ion selected from the group consisting of a quaternary ammonium, phosphonium or sulfonium having one of the following structures: ##STR11## wherein R 3 is a phenyl or an alkyl group of from 1 to 3 carbon atoms, R 4 is a hydrogen or an alkyl group of from 1 to 3 carbon atoms, R 5 is a straight or branched chain of from 1 to 12 carbon atoms, and X is an anion; and (iii) optionally, non-ionic monomer.

Claim 10

Independent Claim 201 words

A method of drilling a well in a subterranean formation comprising circulating into the well, during drilling, an aqueous drilling fluid, the improvement wherein said aqueous drilling fluid comprises: (a) an aqueous clay dispersion; and (b) a water loss reducing amount of a carboxylic functional polyampholyte, or its salt, having an intrinsic viscosity of at least 0.5 dl/g, prepared from: (i) at least one carboxylic functional monomer of the formula: ##STR10## wherein R is hydrogen, a phenyl group or an alkyl group of from 1 to 3 carbon atoms, R 1 is a branched or straight chain of from 0 to 12 carbon atoms, and X is hydrogen or an alkali or alkaline earth metal (ii) at least one cationic-containing monomer containing an ion selected from the group consisting of a quaternary ammonium, phosphonium or sulfonium having one of the following structures: ##STR11## wherein R 3 is a phenyl or an alkyl group of from 1 to 3 carbon atoms, R 4 is a hydrogen or an alkyl group of from 1 to 3 carbon atoms, R 5 is a straight or branched chain of from 1 to 12 carbon atoms, and X is an anion; and (iii) optionally, non-ionic monomer.

Claim 11

Dependent Claim 43 words

The method of claim 8, wherein said polyampholyte is prepared from: (i) 5 to 90%, by weight, of said carboxylic functional monomer; (ii) 0.5 to 85%, by weight, of said cationic-containing monomer; and (iii) 0 to 85%, by weight, of said non-ionic monomer.

Claim 12

Dependent Claim 43 words

The method of claim 8, wherein said polyampholyte is prepared from: (i) 32.5 to 85%, by weight, of said carboxylic functional monomer; (ii) 1.5 to 40%, by weight, of said cationic-containing monomer; and (iii) 5 to 65%, by weight, of said non-ionic monomer.

Claim 13

Dependent Claim 56 words

The method of claim 8, wherein said carboxylic functional monomer is acrylic acid; said non-ionic, monomer is selected from the group consisting of acrylamide, methacrylamide and N,N-dimethyl acrylamide; and said cationic-containing monomer is selected from the group consisting of diethyldiallyl ammonium chloride, dimethyldiallyl ammonium chloride, methacryloyloxy ethyl trimethyl ammonium methylsulfate and methacrylamido propyl timethyl ammonium chloride.

Claim 14

Dependent Claim 197 words

The method of claim 8, wherein said carboxylic functional polyampholyte is a terpolymer prepared from: (i) a carboxylic functional monomer of the formula: ##STR12## wherein R is hydrogen, a phenyl or an alkyl group of from 1 to 3 carbon atoms, R 1 is a branched or straight chain of from 0 to 12 carbon atoms, and X is hydrogen or an alkali or alkaline earth metal; (ii) a monomer of the formula: ##STR13## 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 (iii) a cationic-containing monomer containing an ion selected from the group consisting of a quaternary ammonium, phosphonium or sulfonium having one of the following structures: ##STR14## wherein R 3 is a phenyl or an alkyl group of from 1 to 3 carbon atoms, R 4 is a hydrogen or an alkyl group of from 1 to 3 carbon atoms, R 5 is a straight or branched chain of from 1 to 12 carbon atoms, and X is an anion.

Claim 15

Dependent Claim 20 words

The method of claim 8, wherein at least 0.125 pound of polyampholyte is used per barrel of aqueous clay dispersion.

Claim 16

Dependent Claim 17 words

The method of claim 8, wherein said polyampholyte has an intrinsic viscosity of 0.5 to 4.5 dl/g.

Annuity Stage	Window Opens	Payment Deadline	Surcharge Period Until	Estimated Fee	Status
3.5 Years (Year 4)	1987-06-19	1987-12-19	1988-06-19	$2000.00	Window Closed / Lapsed
7.5 Years (Year 8)	1991-06-19	1991-12-19	1992-06-19	$3760.00	Window Closed / Lapsed
11.5 Years (Year 12)	1995-06-19	1995-12-19	1996-06-19	$7700.00	Window Closed / Lapsed

Ampholytic polymers for use as filtration control aids in drilling muds

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