Fracturing of subterranean formations
AssigneeDowell Schlumberger Incorporated
InventorClare H. Kucera
Life of this patent
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Abstract
Novel aqueous crosslinked gels are described herein which are useful for fracturing subterranean formations. The novel gels are comprised of a solvatable polysaccharide and a soluble zirconium crosslinking agent. The zirconium crosslinking agents are novel and are prepared by reacting a zirconium alkoxide with certain alkanolamines under anhydrous conditions. The zirconium compounds are activated by contact with water. As an example, a zirconium crosslinker was prepared by reacting zirconium tetra(n-propoxide) with triethanolamine in an n-propanol solvent under anhydrous conditions. The zirconium compound thus prepared was activated with water and used to form a stable aqueous crosslinked gel by blending the aqueous crosslinker into an aqueous hydroxypropylguar solution.
Claims22
A process for gelling a solvatable polysaccharide having a plurality of vicinal hydroxy groups oriented sterically in a cis configuration and a molecular weight of at least about 100,000 comprising blending an aqueous solution of said solvatable polysaccharide with a crosslinking amount of a crosslinker composition consisting essentially of
- (a) a product produced by reacting by contacting
- (i) a zirconium alkoxide corresponding to the formula Zr(OR).sub.4 wherein each R independently is an alkyl group of from 1 to about 4 carbon atoms or an inertly-substituted such alkyl group, with
- (ii) an alkanolamine corresponding to the formula R'--N(CH.sub.2 --CH(OH)--R").sub.2, wherein
- (aa) R' is hydrogen or --CH.sub.2 --CH(OH)--R", and
- (bb) R' is hydrogen, methyl or ethyl;
- said process being conducted in a liquid reaction medium under substantially anhydrous conditions and using a molar ratio of a:b of from about 1:2 to about 1:3, and
- (b) a sufficient amount of water to render the product, (a), active as a crosslinker.
In the process for fracturing a subterranean formation penetrated by a wellbore which comprises introducing a hydraulic fracturing fluid into said formation at a flow rate and pressure sufficient to create, reopen and/or extend a fracture in said formation, the improvement comprising using an aqueous crosslinked gel as the hydraulic fracturing fluid which comprises an aqueous solvatable polysaccharide a plurality of vicinal hydroxy groups oriented sterically in a cis configuration and a molecular weight of at least about 100,000, and a crosslinking amount of a crosslinker composition consisting essentially of
- (a) a product produced by reacting by contacting
- (i) a zirconium alkoxide corresponding to the formula Zr(OR).sub.4 wherein each R independently is an alkyl group of from 1 to about 4 carbon atoms or an inertly-substituted such alkyl group, with
- (ii) an alkanolamine corresponding to the formula R'--N(CH.sub.2 --CH(OH)--R").sub.2, wherein
- (aa) R' is hydrogen or --CH.sub.2 --CH(OH)--R", and
- (bb) R' is hydrogen, methyl of ethyl;
- said process being conducted in a liquid reaction medium under substantially anhydrous conditions and using a molar ratio of a:b of from about 1:2 to about 1:3, and
- (b) a sufficient amount of water to render the product, (a), active as a crosslinker.
A process for fracturing a subterranean formation penetrated by a wellbore which comprises the step of:
- (a) substantially continuously injecting
- (i) a crosslinking amount a crosslinker composition consisting essentially of a product produced by reacting by contacting
- (aa) a zirconium alkoxide corresponding to the formula Zr(OR).sub.4 wherein each R independently is an alkyl group of from 1 to about 4 carbon atoms or an inertly-substituted such alkyl group, with
- (bb) an alkanolamine corresponding to the formula R'--N(CH.sub.2 --CH(OH)--R").sub.2, wherein
- (i) R' is hydrogen or --CH.sub.2 --CH(OH)--R", and
- (ii) R' is hydrogen, methyl or ethyl;
- said process being conducted in a liquid reaction medium under substantially anhydrous conditions and using a molar ratio of a:b of from about 1:2 to about 1:3, and
- (ii) a sufficient amount of water to render the product, (i), active as a crosslinker, into
- (iii) a flowing stream of an aqueous solvatable polysaccharide having a plurality of vicinal hydroxy groups oriented sterically in a cis configuration and a molecular weight of at least about 100,000 to thereby form a flowing crosslinkable fracturing fluid
- (b) introducing said flowing crosslinkable fracturing fluid into the wellbore at a flow rate and pressure sufficient to permit said crosslinkable fracturing fluid to gel and increase in viscosity while it is passing through the borehole, and,
- (c) introducing said aqueous gelled fracturing fluid into said formation at a flow rate and pressure at least sufficient to create, reopen and/or extend a fracture in said formation.
A process for gelling a solvatable polysaccharide comprising blending an aqueous solution of said solvatable polysaccharide at a pH of above about 5 with a crosslinking amount of a crosslinker composition consisting essentially of
- (a) a product produced by reacting by contacting
- (i) a zirconium alkoxide corresponding to the formula Zr(OR).sub.4 wherein each R independently is an alkyl group of from 1 to about 4 carbon atoms or an inertly-substituted such alkyl group, with
- (ii) an alkanolamine corresponding to the formula R'--N(CH.sub.2 --CH(OH)--R").sub.2, wherein
- (aa) R' is hydrogen or --CH.sub.2 --CH(OH)--R", and
- (bb) R' is hydrogen, methyl or ethyl;
- said process being conducted in a liquid reaction medium under substantially anhydrous conditions and using a molar ratio of a:b of from about 1:2 to about 1:3, and
- (b) a sufficient amount of water to render the product, (a), active as a crosslinker.
In the process for fracturing a subterranean formation penetrated by a wellbore which comprises introducing a hydraulic fracturing fluid into said formation at a flow rate and pressure sufficient to create, reopen and/or extend a fracture in said formation, the improvement comprising using an aqueous crosslinked gel as the hydraulic fracturing fluid which comprises an aqueous solvatable polysaccharide at a pH above about 5 and a crosslinking amount of
- (a) a product produced by reacting by contacting
- (i) a zirconium alkoxide corresponding to the formula Zr(OR).sub.4 wherein each R independently is an alkyl group of from 1 to about 4 carbon atoms or an inertly-substituted such alkyl group, with
- (ii) an alkanolamine corresponding to the formula R'--N(CH.sub.2 --CH(OH)--R").sub.2, wherein
- (aa) R' is hydrogen or --CH.sub.2 --CH(OH)--R", and
- (bb) R' is hydrogen, methyl or ethyl;
- said process being conducted in a liquid reaction medium under substantially anhydrous conditions and using a molar ratio of a:b of from about 1:2 to about 1:3, and
- (b) a sufficient amount of water to render the product, (a), active as a crosslinker.
A process for fracturing a subterranean formation penetrated by a wellbore which comprises the steps of:
- (a) substantially continuously injecting a crosslinking amount of a crosslinker composition consisting essentially of
- (i) a product produced by reacting by contacting
- (aa) azirconium alkoxide corresponding to the formula Zr(OR).sub.4 wherein each R independently is an alkyl group of from 1 to about 4 carbon atoms or an inertly-substituted such alkyl group, with
- (bb) an alkanolamine corresponding to the formula R'--N(CH.sub.2 --CH(OH)--R").sub.2, wherein
- (i) R' is hydrogen or --CH.sub.2 --CH(OH)--R", and
- (ii) R' is hydrogen, methyl or ethyl;
- said process being conducted in a liquid reaction medium under substantially anhydrous conditions and using a molar ratio of a:b of from about 1:2 to about 1:3, and
- (ii) a sufficient amount of water to render the product, (i), active as a crosslinker into
- (iii) a flowing stream of an aqueous solvatable polysaccharide at a pH above about 5 to thereby form a flowing crosslinkable fracturing fluid,
- (b) introducing said flowing crosslinkable fracturing fluid into the wellbore at a flow rate and pressure sufficient to permit said crosslinkable fracturing fluid to gel and increase in viscosity while it is passing through the wellbore, and
- (c) introducing said aqueous gelled fracturing fluid into said formation at a flow rate and pressure at least sufficient to create, reopen and/or extend a fracture into said formation.
Dependencies are inferred from the claim text.