HIGH TEMPERATURE AQUEOUS-BASED ZIRCONIUM CROSSLINKING COMPOSITION AND USE
A fracturing fluid or crosslinking composition suitable for use at high temperature (275-340° F., 135-171° C.) comprising (a) an aqueous liquid, (b) brine, (c) a thermal stabilizer, (d) a non-delaying alkaline buffer sufficient to provide a pH less than 9, (e) an organic acid, (f) hydroxypropyl guar and (g) a zirconium crosslinking agent. The composition is useful as a fracturing fluid in oil field applications, for example, for hydraulically fracturing a subterranean formation or selectively plugging a permeable zone or leak in a subterranean formation.
1 . A fracturing fluid comprising (a) an aqueous liquid, (b) brine, (c) a thermal stabilizer, (d) a non-delaying alkaline buffer sufficient to provide a pH less than 9, (e) an organic acid, (f) hydroxypropyl guar and (g) a zirconium crosslinking agent.
2 . The fracturing fluid of claim 1 wherein the pH is from 7.5 to 8.9.
3 . The fracturing fluid of claim 1 wherein the pH is from 8.0 to 8.9.
4 . The fracturing fluid of claim 1 wherein the aqueous liquid is selected from the group consisting of water and aqueous alcohol.
5 . The fracturing fluid of claim 1 wherein the buffer is sodium carbonate or potassium carbonate.
6 . The fracturing fluid of claim 5 wherein the brine is tetramethylammonium chloride or potassium chloride.
7 . The fracturing fluid of claim 1 wherein the thermal stabilizer is methanol, alkali metal thiosulfate or ammonium thiosulfate.
8 . The fracturing fluid of claim 1 wherein the acid is formic acid, acetic acid, lactic acid or fumaric acid.
9 . The fracturing fluid of claim 1 wherein the zirconium crosslinking agent is selected from the group consisting of alkanolamine complex, zirconium alkanolamine polyol complex, zirconium lactate ammonium salt, zirconium lactate sodium salt and zirconium lactate alkanolamine salt.
10 . The fracturing fluid of claim 9 wherein the aqueous liquid is water, the brine is tetramethylammonium chloride or potassium chloride, the thermal stabilizer is sodium thiosulfate, the buffer is sodium carbonate, and the acid is fumaric acid.
11 . A method for hydraulically fracturing a subterranean formation comprising introducing into a subterranean formation at a flow rate and pressure sufficient to create, reopen and/or extend a fracture in the formation, (a) an aqueous liquid, (b) brine, (c) a thermal stabilizer, (d) a non-delaying alkaline buffer sufficient to provide a pH less than 9, (e) an organic acid, (f) hydroxypropyl guar and (g) a zirconium crosslinking agent wherein the temperature of the formation is in the range of 275-340° F. (135-171° C.).
12 . The method of claim 11 wherein the aqueous liquid, brine, thermal stabilizer, buffer, acid, hydroxypropyl guar, and the zirconium crosslinking agent are premixed and introduced into the subterranean formation as a single stream.
13 . The method of claim 11 wherein the subterranean formation is penetrated by a wellbore; and the process comprises (a) preparing a base gel by contacting hydroxypropyl guar with an aqueous liquid; (b) introducing the base gel into the wellbore; (c) simultaneously with or sequentially after introducing the base gel into the wellbore, introducing the zirconium crosslinking agent into the wellbore; (d) permitting the base gel and the zirconium crosslinking agent to react to form a crosslinked gel in the wellbore; and (e) introducing the crosslinked gel into the formation from the wellbore at a flow rate and pressure sufficient to create, reopen, and/or extend a fracture in the formation.
14 . The method of claim 13 wherein the zirconium crosslinking agent is in the form of a zirconium solution, which is prepared by dissolving the zirconium crosslinking agent in water or an alcohol.
15 . The method of claim 14 wherein the hydroxypropyl guar is mixed with the aqueous liquid, brine, thermal stabilizer, buffer and acid to provide the base gel.
16 . The method of claim 15 further comprising introducing proppant into the subterranean formation.
17 . A method for plugging a permeable zone or leak in a subterranean formation comprising introducing into said zone or said leak, (a) an aqueous liquid, (b) brine, (c) a thermal stabilizer, (d) a non-delaying alkaline buffer sufficient to provide a pH less than 9, (e) an organic acid, (f) hydroxypropyl guar and (g) a zirconium crosslinking agent wherein the temperature of the zone or formation is in the range of 275-340° F. (135-171° C.).
18 . The method of claim 17 wherein the aqueous liquid, brine, thermal stabilizer, buffer, acid, hydroxypropyl guar, and the zirconium crosslinking agent are premixed and introduced into the subterranean formation as a single stream.
19 . The method of claim 17 wherein the zirconium crosslinking agent and hydroxypropyl guar are not contacted prior to their introduction into the formation and wherein the zone or formation is penetrated by a wellbore comprising (a) preparing a base gel by mixing hydroxypropyl guar with an aqueous liquid; (b) introducing the base gel into the wellbore; (c) simultaneously with or sequentially after introducing the base gel into the wellbore, introducing a zirconium crosslinking agent into the wellbore; (d) permitting the base gel and the zirconium crosslinking agent to react to form a crosslinked gel in the wellbore; and (e) introducing the crosslinked gel from the wellbore into the zone or formation.
20 . The method of claim 19 wherein the zirconium crosslinking agent is in the form of a zirconium solution, which is prepared by dissolving the zirconium crosslinking agent in water or an alcohol.
21 . The method of claim 20 wherein the hydroxypropyl guar is mixed with the aqueous liquid, brine, thermal stabilizer, buffer and acid to provide the base gel.