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US 8,833,457 B2Granted
Sulfates and phosphates as allosteric effectors in mannanohydrolase enzyme breakers
AssigneeBaker Hughes Incorporated
InventorsCharles David Armstrong, Hoang Le, Bharath Rajappa, Qi Qu
Life of this patent
Estimating the term…
Abstract
The allosteric effectors, sulfate and phosphate, can be used with mannanohydrolase enzymes to better control the break of gelled fracturing fluids in wellbore operations. The fracturing fluid contains a hydratable polymer of guar, a guar derivative, a cellulose derivative, a water soluble biopolymer or a combination thereof and a crosslinking agent. The mannanohydrolase enzyme catalyzes the hydrolysis of β-(1,4) mannosidic linkages to break the polymeric backbone.
Claims26
A method of fracturing a subterranean formation comprising introducing into the formation an aqueous fracturing fluid comprising:
- a. a hydratable polymer selected from the group consisting of guar, guar derivatives, cellulose derivatives, water soluble biopolymers, and combinations thereof;
- b. a crosslinking agent for crosslinking the hydratable polymer to form a polymer gel;
- c. an enzyme breaker having an allosteric binding site and comprising at least one of the following:
- i. a mannanohydrolase enzyme that is coded by the nucleotide sequence shown in FIG. 1A, or a nucleotide sequence which is at least 60% homologous with the sequence of FIG. 1A, or when translated, has the amino acid sequence which is at least 60% homologous to the amino acid sequence of FIG. 1B;
- ii. an alkaline mannanohydrolase enzyme that is coded by the nucleotide sequence shown in FIG. 2, or a nucleotide sequence which is at least 60% homologous with the sequence of FIG. 2;
- or
- iii. a mannanohydrolase enzyme that is a member of the glycosyl hydrolase family 5 and is coded for by a gene sequence as depicted in FIG. 2;
- and
- d. an allosteric activator capable of binding to the allosteric binding site of the enzyme breaker, wherein the allosteric activator is selected from the group consisting of sulfates and phosphates.
6 more elements
An aqueous fracturing fluid comprising:
- a. a hydratable polymer selected from the group consisting of guar, guar derivatives, cellulose derivatives, water soluble biopolymers, and combinations thereof;
- b. a crosslinking agent for crosslinking the hydratable polymer to form a polymer gel;
- c. an enzyme breaker having an allosteric binding site and comprising at least one of the following:
- i. a mannanohydrolase enzyme that is coded by the nucleotide sequence shown in FIG. 1A, or a nucleotide sequence which is at least 60% homologous with the sequence of FIG. 1A, or when translated, has the amino acid sequence which is at least 60% homologous to the amino acid sequence of FIG. 1B;
- ii. an alkaline mannanohydrolase enzyme that is coded by the nucleotide sequence shown in FIG. 2, or a nucleotide sequence which is at least 60% homologous with the sequence of FIG. 2;
- or
- iii. a mannanohydrolase enzyme that is a member of the glycosyl hydrolase family 5 and is coded for by a gene sequence as depicted in FIG. 2;
- and
- d. an allosteric activator capable of binding to the allosteric binding site of the enzyme breaker, wherein the allosteric activator is selected from the group consisting of sulfates and phosphates.
6 more elements
A method of fracturing a subterranean formation comprising introducing into the formation an aqueous fracturing fluid comprising:
- a) a hydratable polymer selected from the group consisting of guar, guar derivatives, cellulose derivatives, water soluble biopolymers, and combinations thereof;
- b) a crosslinking agent for crosslinking the hydratable polymer to form a polymer gel;
- c) an enzyme breaker having an allosteric binding site comprising at least one of the following:
- (i) a mannanohydrolase enzyme that is coded by the nucleotide sequence shown in FIG. 1A, or a nucleotide sequence which is at least 60% homologous with the sequence of FIG. 1A, or when translated, has the amino acid sequence which is at least 60% homologous to the amino acid sequence of FIG. 1B;
- (ii) a mannanohydrolase enzyme that is coded by the nucleotide sequence shown in FIG. 2, or a nucleotide sequence which is at least 60% homologous with the sequence of FIG. 2;
- or
- (iii) an mannanohydrolase enzyme that is a member of the glycosyl hydrolase family 5 and is coded for by a gene sequence as depicted in FIG. 2;
- and
- d) an allosteric activator selected from the group consisting of sulfates and phosphates;
- and
- enhancing the activity of the enzyme breaker by binding the allosteric activator to the allosteric binding site of the enzyme breaker.
8 more elements
Dependencies are inferred from the claim text.