Method of fracturing using mannanohydrolase enzyme breaker
AssigneeBaker Hughes Incorporated
InventorCharles David Armstrong
Life of this patent
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Abstract
A thermophilic mannanohydrolase enzyme may be used as an enzyme breaker for fracturing fluids containing hydratable polymers of guar and underivatized guar. The amino acid sequence of the mannanohydrolase is at least 90% homologous to the amino acid sequence of SEQ ID NO:2.
Claims20
A method of hydraulic fracturing a subterranean formation which comprises introducing into the formation at a pressure sufficient to create or enlarge fractures in the formation a fracturing fluid having a pH from about 8.5 to about 11.0 comprising:
- (a) a hydratable polymer selected from the group consisting of underivatized guars and derivatized guars;
- (b) a crosslinking agent for crosslinking the hydratable polymer to form a polymer gel;
- and
- (c) an enzyme breaker comprising a mannanohydrolase enzyme that has an amino acid sequence that is at least 90% homologous to the amino acid sequence of SEQ ID NO:2.
A method of hydraulic fracturing a subterranean formation penetrated by a well comprising:
- (a) pumping into the well at a pressure sufficient to create or enlarge fractures in the formation a fracturing fluid comprising:
- (i) a hydratable polymer selected from the group consisting of underivatized guars and derivatized guars;
- (ii) a crosslinking agent for crosslinking the hydratable polymer to form a polymer gel;
- (iii) an enzyme breaker comprising a mannanohydrolase enzyme that has an amino acid sequence that is at least 90% homologous to the amino acid sequence of SEQ ID NO:2;
- and
- (iv) proppant;
- and
- (b) creating a partial monolayer of proppant in the created or enlarged fracture.
In a method of hydraulic fracturing a subterranean formation penetrated by a well wherein a fracturing fluid containing derivatized or underivatized guar, a crosslinking agent and an enzyme breaker is pumped into a well at a pressure sufficient to create or enlarge fractures in the formation, the improvement being use of a thermophilic mannanohydrolase as enzyme breaker, the thermophilic mannanohydrolase having an amino acid sequence that is at least 90% homologous to the amino acid sequence of SEQ ID NO:2.
Dependencies are inferred from the claim text.