US4473480A — High temperature stable fluid loss control system

Claim 1

Independent Claim 306 words

A composition capable of imparting fluid loss control to aqueous systems comprising a mixture of: (a) a substantially water insoluble, solid, particulate silicate or alumino-silicate material which contains a major amount of kaolinite, halloysite, montmorillonite or illite or mixtures thereof, or attapulgite or sepiolite and being of a particle size such that at least about 90 percent by weight is capable of passing through a No. 20 U.S. Standard Sieve; in combination with (b) a chemical compound capable of converting to a higher oxidation state under alkaline conditions selected from the group consisting of C 1 -C 5 alkanols, unsubstituted or C 1 -C 3 alkyl, aryl or alkaryl substituted phenols, hydroquinone, tert-butyl catechol, C 1 -C 15 alkanethiol, alkali metal, alkaline earth metal or ammonium salt of sulfite, bifulfite and nitrite, ferrous metal salts of chloride and sulfate and cuprous metal salts of chloride and sulfate; in combination with (c) a reaction product formed between a polymeric material having a weight average molecular weight of at least about 20,000 selected from the group consisting of polyvinyl alcohol and hydroxy C 1 -C 3 alkyl cellulose and from about 0.1 to 200 percent of stoichiometry of a cross-linking agent selected from the group consisting of a compound containing at least one aldehyde group therein or a compound capable of generating in situ at least one aldehyde or an epihalohydrin; the reaction between said polymeric material and said aldehyde carried out in an aqueous acidic medium having a pH of 5.5 or less and the reaction between said polymer and said epihalohydrin being carried out in an aqueous basic medium having a pH of at least about 9.5; wherein the weight ratio of component (a) to (c) is from about 0.5:1 to 20:1 and of component (b) to (c) is at least from about 0.2:1 to 1:1.

Claim 2

Dependent Claim 306 words

A composition capable of imparting fluid loss control to aqueous systems comprising a mixture of: (a) a substantially water insoluble, solid, particulate silicate or alumino-silicate material which contains a major amount of kaolinite, halloysite, montmorillonite or illite or mixtures thereof, or attapulgite or sepiolite and being of a particle size such that at least about 90 percent by weight is capable of passing through a No. 20 U.S. Standard Sieve; in combination with (b) a chemical compound capable of converting to a higher oxidation state under alkaline conditions selected from the group consisting of C 1 -C 5 alkanols, unsubstituted or C 1 -C 3 alkyl, aryl or alkaryl substituted phenols, hydroquinone, tert-butyl catechol, C 1 -C 15 alkanethiol, alkali metal, alkaline earth metal or ammonium salt of sulfite, bifulfite and nitrite, ferrous metal salts of chloride and sulfate and cuprous metal salts of chloride and sulfate; in combination with (c) a reaction product formed between a polymeric material having a weight average molecular weight of at least about 20,000 selected from the group consisting of polyvinyl alcohol and hydroxy C 1 -C 3 alkyl cellulose and from about 0.1 to 200 percent of stoichiometry of a cross-linking agent selected from the group consisting of a compound containing at least one aldehyde group therein or a compound capable of generating in situ at least one aldehyde or an epihalohydrin; the reaction between said polymeric material and said aldehyde carried out in an aqueous acidic medium having a pH of 5.5 or less and the reaction between said polymer and said epihalohydrin being carried out in an aqueous basic medium having a pH of at least about 9.5; wherein the weight ratio of component (a) to (c) is from about 0.5:1 to 20:1 and of component (b) to (c) is at least from about 0.2:1 to 1:1.

Claim 3

Dependent Claim 47 words

The composition of claim 1 wherein the aldehyde containing or generating agent of (c) is selected from the group consisting of formaldehyde, acetaldehyde, propionaldehyde, glycolaldehyde, glyoxylic acid, glyoxal, glutaraldehyde, paraformaldehyde, trimethylol melamine, hexamethylol melamine, tri(C 1 -C 3 alkoxymethyl) melamine or hexa(C 1 -C 3 alkoxymethyl) malamine.

Claim 4

Dependent Claim 14 words

The compositions of claim 1 wherein the mixture is dispersed in an aqueous medium.

Claim 5

Dependent Claim 39 words

The composition of claim 1 wherein component (b) is selected from the group consisting essentially of C 1 to C 5 alkanols, or alkali metal, alkaline earth metal or ammonium salts of sulfite, bisulfite and nitrite or mixtures thereof.

Claim 6

Dependent Claim 46 words

The composition of claim 1, wherein the component (c) is formed from polyvinyl alcohol having a weight average molecular weight of from about 90,000 to 200,000 and at least about 75 percent hydrolyzed and the ratio of (a) to (c) is from about 1:1 to 10:1.

Claim 7

Dependent Claim 89 words

In a water-based, clay-free drilling fluid suitable for circulating in a bore hole while drilling the bore hole into subterranean formations which includes water, a weighting agent, a rheology enhancing agent and a fluid-loss controller, the improvement being that said fluid-loss controlling agent comprises the composition of claim 1, said composition being present in said fluid in from about 1 to 15 percent by weight based on the weight of the water of said fluid and said fluid being maintained at a pH of from about 8 to 11.5.

Claim 8

Dependent Claim 87 words

In a water-based, clay-free drilling fluid suitable for circulating in a bore hole while drilling the bore hole into subterranean formations which includes water, a weighting agent, a rheology enhancing agent and a fluid-loss controller, said improvement comprises that said fluid-loss controlling agent comprises the composition of claim 2 present in said fluid in from about 1 to 15 percent by weight based on the weight of the water present in said fluid and said fluid is maintained at a pH of from about 8 to 11.5.

Claim 9

Dependent Claim 87 words

In a water-based, clay-free drilling fluid suitable for circulating in a bore hole while drilling the bore hole into subterranean formations which includes water, a weighting agent, a rheology enhancing agent and a fluid-loss controller, said improvement comprises that said fluid-loss controlling agent comprises the composition of claim 3 present in said fluid in from about 1 to 15 percent by weight based on the weight of the water present in said fluid and said fluid is maintained at a pH of from about 8 to 11.5.

Claim 10

Dependent Claim 87 words

In a water-based, clay-free drilling fluid suitable for circulating in a bore hole while drilling the bore hole into subterranean formations which includes water, a weighting agent, a rheology enhancing agent and a fluid-loss controller, said improvement comprises that said fluid-loss controlling agent comprises the composition of claim 4 present in said fluid in from about 1 to 15 percent by weight based on the weight of the water present in said fluid and said fluid is maintained at a pH of from about 8 to 11.5.

Claim 11

Dependent Claim 87 words

In a water-based, clay-free drilling fluid suitable for circulating in a bore hole while drilling the bore hole into subterranean formations which includes water, a weighting agent, a rheology enhancing agent and a fluid-loss controller, said improvement comprises that said fluid-loss controlling agent comprises the composition of claim 5 present in said fluid in from about 1 to 15 percent by weight based on the weight of the water present in said fluid and said fluid is maintained at a pH of from about 8 to 11.5.

Claim 12

Dependent Claim 34 words

In a process of drilling a bore hole into a subterranean formation using conventional bore hole drilling equipment, the improvement comprising circulating in the bore hole while drilling the drilling fluid of claim 6.

Claim 13

Dependent Claim 34 words

In a process of drilling a bore hole into a subterranean formation using conventional bore hole drilling equipment, the improvement comprising circulating in the bore hole while drilling the drilling fluid of claim 7.

Claim 14

Dependent Claim 34 words

In a process of drilling a bore hole into a subterranean formation using conventional bore hole drilling equipment, the improvement comprising circulating in the bore hole while drilling the drilling fluid of claim 8.

Claim 15

Dependent Claim 34 words

In a process of drilling a bore hole into a subterranean formation using conventional bore hole drilling equipment, the improvement comprising circulating in the bore hole while drilling the drilling fluid of claim 9.

Claim 16

Dependent Claim 34 words

In a process of drilling a bore hole into a subterranean formation using conventional bore hole drilling equipment, the improvement comprising circulating in the bore hole while drilling the drilling fluid of claim 10.

Annuity Stage	Window Opens	Payment Deadline	Surcharge Period Until	Estimated Fee	Status
3.5 Years (Year 4)	1987-09-25	1988-03-26	1988-09-25	$2000.00	Window Closed / Lapsed
7.5 Years (Year 8)	1991-09-25	1992-03-26	1992-09-25	$3760.00	Window Closed / Lapsed
11.5 Years (Year 12)	1995-09-25	1996-03-26	1996-09-25	$7700.00	Window Closed / Lapsed

High temperature stable fluid loss control system

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