Compositions for fracturing subterranean formations
First Claim
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1. A hydraulic fracturing fluid useful for fracturing a subterranean formation which surrounds a well bore, said fracturing fluid comprising:
- (a) an aqueous liquid;
(b) a polysaccharide soluble or dispersible in said aqueous liquid in an amount sufficient to increase the viscosity of said aqueous liquid; and
(c) an enzyme breaker which degrades said polysaccharide at a temperature above 195°
F. and which is essentially incapable of degrading said polysaccharide at a temperature of 100°
F. or less, wherein said enzyme breaker comprises, in combination, a mannanase which hydrolyzes β
-1,4 hemicellulolytic linkages in galactomannans and an α
-galactosidase which hydrolyzes α
-1,6 hemicellulolytic linkages In galactomannans, said enzyme breaker Included in an amount effective to degrade said polysaccharide at said temperature.
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Abstract
A method of fracturing a subterranean formation which surrounds a well bore comprises the steps of providing a fracturing fluid, and injecting the fracturing fluid into the well bore at a pressure sufficient to form fractures in the subterranean formation which surrounds the well bore. The pressure is then released from the fracturing fluid, after which the fluid may be removed from the well and the well placed into production. The fracturing fluid comprises an aqueous liquid, a polysaccharide soluble or dispersible in the aqueous liquid in an amount sufficient to increase the viscosity of the aqueous liquid, an enzyme breaker which degrades said polysaccharide at a temperature above 180° F. Fracturing fluid compositions and enzyme breaker systems useful for carrying out the invention are also disclosed.
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Citations
18 Claims
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1. A hydraulic fracturing fluid useful for fracturing a subterranean formation which surrounds a well bore, said fracturing fluid comprising:
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(a) an aqueous liquid; (b) a polysaccharide soluble or dispersible in said aqueous liquid in an amount sufficient to increase the viscosity of said aqueous liquid; and (c) an enzyme breaker which degrades said polysaccharide at a temperature above 195°
F. and which is essentially incapable of degrading said polysaccharide at a temperature of 100°
F. or less, wherein said enzyme breaker comprises, in combination, a mannanase which hydrolyzes β
-1,4 hemicellulolytic linkages in galactomannans and an α
-galactosidase which hydrolyzes α
-1,6 hemicellulolytic linkages In galactomannans, said enzyme breaker Included in an amount effective to degrade said polysaccharide at said temperature. - View Dependent Claims (2, 3, 4, 5, 6, 7, 15, 17, 18)
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8. A hydraulic fracturing fluid useful for fracturing a subterranean formation which surrounds a well bore, said fracturing fluid comprising:
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(a) an aqueous liquid; (b) a polysaccharide soluble or dispersible in said aqueous liquid in an amount sufficient to increase the viscosity of said aqueous liquid; and (c) an enzyme breaker which degrades said polysaccharide at a temperature above 195°
F. and which is essentially incapable of degrading said polysaccharide at a temperature of 100°
F. or less, wherein said enzyme breaker comprises, in combination, a mannanase which hydrolyzes β
-1,4 hemicellulolytic linkages in galactomannans and an α
-galactosidase which hydrolyzes α
-1,6 hemicellulolytic linkages In galactomannans, where said mannanase and said α
-galactosidase hydrolyze said linkages at a temperature above 180°
F. and are essentially incapable of degrading said linkages at a temperature of 100°
F. or less, said enzyme breaker included in an amount effective to degrade said polysaccharide at said temperature. - View Dependent Claims (9, 10, 11, 12)
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13. A breaker composition useful for preparing hydraulic fracturing fluids for fracturing a subterranean formation Which surrounds a well bore, where said breaker composition is active at a temperature above 195°
- F. and is essentially inactive at a temperature of 100°
F. or less, and where said breaker composition comprises an enzyme breaker comprising, In combination, a mannanase which hydrolyzes β
-1,4 hemicellulolytic linkages In galactomannans and an α
-galactosidase which hydrolyzes α
-1,6 hemicellulolytic linkages In galactomannans. - View Dependent Claims (14, 16)
- F. and is essentially inactive at a temperature of 100°
Specification
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Current AssigneeThe Trustees of Princeton University (Princeton University), North Carolina State University (University of North Carolina System)
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Original AssigneeThe Trustees of Princeton University (Princeton University), North Carolina State University (University of North Carolina System)
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InventorsPrud'homme, Robert K., Khan, Saad A., Kelly, Robert M., Leduc, Pascal, Tayal, Akash
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Primary Examiner(s)KELLY, CYNTHIA HARRIS
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Application NumberUS08/403,078Time in Patent Office1,429 DaysField of Search507/211, 507/217, 507/922, 435/209US Class Current507/211CPC Class CodesC09K 8/62 Compositions for forming cr...C09K 8/685 containing cross-linking ag...E21B 43/267 reinforcing fractures by pr...Y10S 507/921 Specified breaker component...Y10S 507/922 Fracture fluidY10S 507/923 Fracture acidizing
