Method of treating subterranean formation with crosslinked polymer fluid
A method of treating a subterranean formation penetrated by a wellbore utilizes a treating fluid formed from an aqueous solution of a water-soluble polymer. The treating fluid further contains a crosslinking agent and an optional delayed release alkaline additive. The delayed release alkaline additive may be at least one of urea, a urea derivative, a solid alkaline earth metal carbonate, a solid alkaline earth metal oxide and combinations of these. The treating fluid further includes an acidic pH adjusting agent used in an amount to provide the treating fluid with a pH of less than about 5. The treating fluid is then introduced into the formation.
1. A method of treating a subterranean formation penetrated by a wellbore comprising:
forming a treating fluid comprising
an aqueous solution of a water-soluble polymer, a crosslinking agent, and
an acidic pH adjusting agent,
the acidic pH adjusting agent incorporated in an amount adequate to provide the
fluid with a shear recovery time of 5 minutes or less; and,
introducing the treating fluid into the formation at a pressure sufficient to treat the formation.
2. The method of claim 1 , wherein the fluid further comprises a delayed release alkaline additive of at least one of urea, a urea derivative, a solid alkaline earth metal carbonate, a solid alkaline earth metal oxide and combinations thereof.
3. The method of claim 1 , wherein the acidic pH adjusting agent used in an amount to provide the treating fluid with a pH of less than about 5.
4. The method of claim 1 , wherein the crosslinking agent includes a metal compound selected from Zr, Ti, Cr, or Hf organo-metallic compounds.
5. The method of claim 2 , wherein the delayed release alkaline additive is used in an amount of from about 0.01% to about 0.5% by weight of fluid.
6. The method of claim 1 , wherein the crosslinking agent is a zirconium crosslinking agent.
7. The method of claim 1 , wherein the acidic pH adjusting agent is selected from at least one of a carboxylic acid and an inorganic acid, and wherein the carboxylic acid includes acetic acid, formic acid, propionic acid and glycolic acid and the inorganic acid includes hydrochloric acid and sulfuric acid.
8. The method of claim 1 , wherein the water-soluble polymer is a carboxyalkyl hydroxyalkyl guar polymer, and wherein the alkyl radicals of the carboxyalkyl hydroxyalkyl guar polymer are selected from methyl, ethyl and propyl radicals.
9. The method of claim 8 , wherein the carboxyalkyl hydroxyalkyl guar polymer is carboxymethyl hydroxypropyl guar.
10. The method of claim 1 , wherein the water-soluble polymer is selected from at least one of hydroxyethylcellulose, hydroxypropylcellulose, carboxymethylhydroxyethylcellulose, xanthan, diutan, scleroglucan, polyacrylamide and polyacrylate.
11. The method of claim 1 , wherein the alkaline earth metal carbonate or oxide is selected from at least one of MgCO 3 , MgO, CaCO 3 , Ca(OH) 2 , CaO and SrCO 3 .
12. The method of claim 1 , wherein the polymer is present within the treating fluid in an amount of from about 0.1% to about 1.5% by weight of fluid.
13. The method of claim 1 , wherein the crosslinking agent is used in an amount of from about 0.01% to about 0.15% by weight of fluid.
14. The method of claim 1 , wherein the treating fluid is adjusted to a pH of less than about 4.5.
15. The method of claim 1 , wherein the treating fluid exhibits a shear recovery time of less than 5 minutes when subjected to a shear sufficient to break the crosslinked polymer treatment fluid at a temperature of from about 40° C. to about 180° C.
16. The method of claim 1 as used for formation stimulation treatments, wellbore cleanout, gravel packing, diversion, fluid loss control, scale removal, diversion, acidizing, matrix treatment, or clean-up.
17. A method of treating a subterranean formation penetrated by a wellbore comprising:
forming a treating fluid comprising
an aqueous solution of a water-soluble polymer, a crosslinking agent, and an
acidic pH adjusting agent,
the acidic pH adjusting agent incorporated in an amount adequate to provide the
fluid with a recovered viscosity ratio of about 0.70 or greater at 10 minutes; and,
introducing the treating fluid into the formation.