Patent ID: 7497263

Claim:
A process for stimulating a subterranean formation adjacent a wellbore by delivering a fracturing fluid at a pumping rate into the formation, the method comprising: continuously mixing a hydratable polymer and water at a mixing temperature; passing the mixture through a first in/first out system sized, based on the pumping rate, the mixing temperature, and the nature of the polymer, to provide a residence time of the mixture in the system corresponding to a time needed to bring the polymer to a degree of hydration of more than about 10% but less than about 75%; initiating crosslinking of the polymer with a boron crosslinker before the hydration degree exceeds about 75%; prior to or simultaneous with initiation of crosslinking, adding a polyol comprising 1,2-cis hydroxyl groups to the polymer/water mixture; and injecting the fracturing fluid comprising polymer, crosslinker, polyol, and water, into the formation, at a delivery rate of from about 20 to about 70 barrels per minute.