Method for fracturing high temperature subterranean formations
AssigneeThe Western Company of North America
InventorsD. V. Satyanarayana Gupta, Vernon L. Franklin
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Abstract
A method for hydraulic fracturing using crosslinked guar polymers wherein the high temperature viscosity and thermal stability of said polymers is maximized by adjusting the pH such that the cationic charge density of the polymer is at its maximum. These maximums occur for guar at a pH of 10.5 and for carboxymethylhydroxypropyl guar at a pH of 10.7.
Claims14
A process for fracturing a subterranean formation which comprises introducing into said formation at a flow rate and pressure sufficient to produce a fracture in said formation, a fluid comprised of an aqueous gel comprising an aqueous fluid, a gelling agent and a transition metal chelate crosslinking agent wherein said gelling agent is selected from the group consisting of guar, hydroxypropylguar, carboxymethylguar and carboxymethylhydroxypropylguar, wherein said crosslinking agent is present in an amount of at least 0.0005 percent by weight of said aqueous gel and wherein the pH of said fluid is maintained essentially at the pH which provides the maximum cationic charge density in said gelling agent.
A process for fracturing a subterranean formation which comprises introducing into said formation, at a flow rate and pressure sufficient to produce a fracture in said formation a fluid comprised of an aqueous gel and a propping agent, said aqueous gel comprising an aqueous fluid, a guar or derivitized guar gelling agent and a zirconium chelate crosslinking agent wherein said gelling agent is present at from about 15 to about 60 pounds per thousand gallons of aqueous fluid, said crosslinking agent is present at from 0.01 to about 10 pounds per thousand gallons of aqueous fluid, wherein the bottom hole temperature of said subterranean formation is above 200.degree. F., and wherein the pH of said fluid is maintained between about 10.5 and about 12.
Dependencies are inferred from the claim text.