US3960736A
Expired / Lapsed
US
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Self-breaking viscous aqueous solutions and the use thereof in fracturing subterranean formations
Assignee: Schlumberger Technology Corp
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Filing: 1974-06-03
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Granted: 1976-06-01
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Expires: 1994-06-03
Abstract
Abstract Viscous aqueous solutions are prepared which maintain a certain viscosity range over a predetermined period of time (i.e., induction period) and which thereafter break, i.e., decrease in viscosity over a very short period of time. The viscous aqueous solution comprises a polysaccharide having an ability to thicken water and dispersed or dissolved in the aqueous solution an effective quantity of an organic ester which, at a temperature at which it is desired to break the viscous solution, hydrolyzes over a delayed period of time to form an acid which degrades the polysaccharide, thus causing a splitting of the polysaccharide chain and a decrease in the viscosity of the solution.
Inventors
- 👤 Dustin L. Free
- 👤 Karl L. Krumel
- 👤 Travis C. Snyder
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-25 10:14
CPC Classifications
C; C09; C09K; C09K8/00; C09K8/60; C09K8/62; E; E21; E21B; E21B43/00; E21B43/25; E21B43/26; Y; Y10; Y10S; Y10S507/00; Y10S507/921; Y10S507/922
Claims Analysis
Total Claims: 19
Claim 1
Independent Claim
130 words
A viscous aqueous well treating composition which has a certain viscosity for a predetermined period of time at a certain temperature and which subsequently breaks to form a lower viscosity fluid within a short period of time, which comprises: a viscous aqueous solution containing a sufficient quantity of a polysaccharide-thickening agent, containing acetal linkages and which, in an aqueous solution is degraded by an acid to provide a solution having a desired viscosity at the temperature of use and an effective quantity of a C 1 - C 12 organic ester of a carboxylic acid, which hydrolyzes in said aqueous solution at said temperature of use to produce an acid which degrades the polysaccharide and causes the viscosity of the aqueous composition to be lowered to a desired lower level.
Claim 2
Dependent Claim
130 words
A viscous aqueous well treating composition which has a certain viscosity for a predetermined period of time at a certain temperature and which subsequently breaks to form a lower viscosity fluid within a short period of time, which comprises: a viscous aqueous solution containing a sufficient quantity of a polysaccharide-thickening agent, containing acetal linkages and which, in an aqueous solution is degraded by an acid to provide a solution having a desired viscosity at the temperature of use and an effective quantity of a C 1 - C 12 organic ester of a carboxylic acid, which hydrolyzes in said aqueous solution at said temperature of use to produce an acid which degrades the polysaccharide and causes the viscosity of the aqueous composition to be lowered to a desired lower level.
Claim 3
Dependent Claim
31 words
The composition of claim 1 wherein the organic ester consists of a dicarboxylic acid ester which has an accelerated rate of hydrolysis at an elevated temperature of at least about 150°F.
Claim 4
Dependent Claim
12 words
The composition of claim 1 wherein the polysaccharide is a cellulose ether.
Claim 5
Dependent Claim
15 words
The composition of claim 3 wherein the organic ester consists of a dicarboxylic acid ester.
Claim 6
Dependent Claim
36 words
The composition of claim 4 wherein the organic ester is present in the composition in an amount ranging from about 0.02 to about 2.0 equivalent weight of said organic ester per equivalent weight of said polysaccharide.
Claim 7
Dependent Claim
40 words
The composition of claim 1 wherein a sufficient quantity of polysaccharide is present to provide a viscous aqueous composition having a viscosity ranging from about 20 to about 1000 centipoise at a temperature ranging from about 60° to about 200°F.
Claim 8
Dependent Claim
12 words
The composition of claim 6 wherein the polysaccharide is a cellulose ether.
Claim 9
Dependent Claim
14 words
The composition of claim 7 wherein the organic ester is a dicarboxylic acid ester.
Claim 10
Dependent Claim
36 words
The composition of claim 8 wherein the organic ester is present in said composition in an amount ranging from about 0.02 to about 2.0 equivalent weights of said organic ester per equivalent weight of said polysaccharide.
Claim 11
Dependent Claim
45 words
A method of fracturing a subterranean formation penetrated by a borehole, said formation being substantially free of acid soluble minerals which comprises: injecting through said borehole and in contact with said formation the composition of claim 1 at a sufficient pressure to fracture said formation.
Claim 12
Dependent Claim
31 words
The method of claim 10 wherein the organic ester consists of a dicarboxylic acid ester which has an accelerated rate of hydrolysis at an elevated temperature of at least about 150°F.
Claim 13
Dependent Claim
12 words
The method of claim 10 wherein the polysaccharide is a cellulose ether.
Claim 14
Dependent Claim
15 words
The method of claim 12 wherein the organic ester consists of a dicarboxylic acid ester.
Claim 15
Dependent Claim
36 words
The method of claim 13 wherein the organic ester is present in the composition in an amount ranging from about 0.02 to about 2.0 equivalent weight of said organic ester per equivalent weight of said polysaccharide.
Claim 16
Dependent Claim
40 words
The method of claim 10 wherein a sufficient quantity of polysaccharide is present to provide a viscous aqueous composition having a viscosity ranging from about 20 to about 1000 centipoise at a temperature ranging from about 60° to about 200°F.
Claim 17
Dependent Claim
12 words
The method of claim 15 wherein the polysaccharide is a cellulose ether.
Claim 18
Dependent Claim
14 words
The method of claim 16 wherein the organic ester is a dicarboxylic acid ester.
Claim 19
Dependent Claim
36 words
The method of claim 17 wherein the organic ester is present in said composition in an amount ranging from about 0.02 to about 2.0 equivalent weights of said organic ester per equivalent weight of said polysaccharide.
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USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1979-06-01 | 1979-12-01 | 1980-06-01 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1983-06-01 | 1983-12-01 | 1984-06-01 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1987-06-01 | 1987-12-01 | 1988-06-01 | $7700.00 | Window Closed / Lapsed |