Method for stimulation of wells with carbon dioxide or nitrogen based

Abstract

The present invention relates to a method of fracturing subterranean formations and placing proppant material in the created fracture utilizing carbon dioxide or nitrogen containing fluid. An aqueous liquid-liquid carbon dioxide emulsion fluid is prepared having an internal phase ratio in the range of from about 50 to in excess of about 96 percent and introduced into the subterranean formation to be fractured. The emulsion is heated by the formation to a temperature above the critical temperature of carbon dioxide and the carbon dioxide is caused to be converted to a vapor whereupon the emulsion becomes a foam. The volume of liquid carbon dioxide is adjusted as the volume of proppant material varies to at least substantially maintain a constant internal phase ratio in the treatment fluid. When nitrogen is utilized, a foam is produced on the surface by admixing gaseous nitrogen with the gelled fluid. The formation is fractured by the treatment fluid and the proppant is placed in the created fracture. The fluid having maintained therein substantially a constant internal phase ratio is capable of transporting greater quantities of proppant than foams having a comparable quality.