Patent ID: 6923264

Claim:
An improved method of fracturing a subterranean zone penetrated by a well bore at temperatures below about 2000° F. comprising the steps of: (a) providing a fracturing fluid comprised of water, a viscosity increasing gelling agent, a particulate proppant material, a delayed viscosity breaker for causing said fracturing fluid to revert to a thin fluid and a breaker activator comprising a mixture selected from the group consisting of a mixture of cobaltous acetate and the sodium salt of ethylenediaminetetraacetic acid and a mixture of thioglycolic acid and sodium molybdate; (b) pumping said fracturing fluid into said subterranean zone at a rate and pressure sufficient to create and extend at least one fracture in said subterranean zone; and (c) allowing said fracturing fluid to break whereby said particulate proppant material is deposited in said fracture and said fracturing fluid is recovered from said subterranean zone.