US Patent 7268101 Formate based liquid gel concentrates

A liquid gel concentrate for forming a high viscosity treating fluid is provided which can be premixed and stored before being used. The concentrate is comprised of an aqueous formate solution, at least one hydratable polymer which yields viscosity upon hydration and optionally an inhibitor having the property of reversibly reacting with the hydratable polymer in a manner whereby the rate of hydration of the polymer is retarded. Upon the selective reversal of the hydration inhibiting reaction the polymer is hydrated and high viscosity yielded thereby. The concentrate can be diluted with water to hydrate the hydratable polymer and form a large volume of high viscosity treating fluid.