Method of fracturing with aphron containing fluids

Abstract

Subterranean formations may be stimulated by introducing into the formation a fluid containing a viscosifying agent and aphrons. The viscosifying agent may be a linear gel, crosslinked gel or a viscoelastic surfactant. The aphrons in the fluid move faster than the liquid phase of the fluid and thus move toward the front of the fluid as the fluid is being pumped into the formation. The bubble barrier and radial-flow pattern of the fluid rapidly reduce the shear rate and raise the fluid viscosity, severely curtailing fluid invasion into the formation especially in those formations where high leak-off potential exists.

What is claimed is: 
     
         1 . A method of fracturing a subterranean formation penetrated by a well comprising introducing into the well at a pressure sufficient to create or enlarge a fracture in the subterranean formation an aqueous fluid comprising a viscosifying agent and aphrons. 
     
     
         2 . The method of  claim 1 , wherein the aqueous fluid further comprises a foaming gas. 
     
     
         3 . The method of  claim 2 , wherein the foaming gas is nitrogen, carbon dioxide, or a mixture thereof. 
     
     
         4 . The method of  claim 3 , wherein the foaming gas is present in the aqueous fluid in a quantity, by volume of 63% to in excess of 96%. 
     
     
         5 . The method of  claim 1 , wherein the aqueous fluid is a linear gel. 
     
     
         6 . The method of  claim 1 , wherein the viscosifying agent is a viscoelastic surfactant. 
     
     
         7 . The method of  claim 1 , wherein the viscosifying agent is selected from the group consisting of galactomannan gums, cellulose and cellulose derivatives, starch, starch derivatives, xanthan, derivatized xanthan and mixtures thereof. 
     
     
         8 . The method of  claim 7 , wherein the viscosifying agent is a galactomannan gum selected from the group consisting of hydroxypropyl guar, carboxymethylhydroxypropyl guar and underivatized guar. 
     
     
         9 . The method of  claim 7 , wherein the viscosifying agent is xanthan gum. 
     
     
         10 . The method of  claim 1 , wherein the viscosifying agent is a blend comprising xanthan gum, starch and an oligosaccharide. 
     
     
         11 . The method of  claim 1 , wherein the viscosifying agent is a blend of hydroxypropyl guar, a betaine and an alcohol ether sulfate. 
     
     
         12 . The method of  claim 1 , wherein the viscosifying agent is selected from the group consisting of underivatized guar and carboxymethylhydroxypropyl guar. 
     
     
         13 . The method of  claim 1 , wherein the aqueous fluid has a viscosity less than 1,000 at a shear rate of 100 sec −1 . 
     
     
         14 . The method of  claim 1 , wherein the aqueous fluid further comprises at least one aphron stabilizer. 
     
     
         15 . The method of  claim 14 , wherein the aphron stabilizer comprises polyvinyl alcohol, a betaine, an alkyl ether sulfate, or a mixture thereof 
     
     
         16 . A method of fracturing a subterranean formation penetrated by a well comprising introducing into the well at a pressure sufficient to create or enlarge a fracture in the subterranean formation an aqueous fluid comprising a non-crosslinked linear viscosifying agent and aphrons, wherein the length of the fracture is greater than the length of the fracture created in a substantially similar aqueous fluid which does not contain aphrons. 
     
     
         17 . The method of  claim 16 , wherein the aqueous fluid is foamed. 
     
     
         18 . A method of reducing fluid loss into a subterranean formation penetrated by a well during fracturing of the subterranean formation, the method comprising introducing into the well at a pressure sufficient to create or enlarge a fracture in the subterranean formation an aqueous fluid comprising a viscosifying agent and aphrons wherein the amount of fluid loss into the subterranean formation is less than the amount of fluid loss into the subterranean formation when a substantially similar aqueous fluid which does not contain aphrons is introduced into the subterranean formation and further wherein the aqueous fluid does not circulate within the well during fracturing. 
     
     
         19 . The method of  claim 18 , wherein the aqueous fluid is foamed. 
     
     
         20 . The method of  claim 18 , wherein the viscosifying agent is selected from the group consisting of galactomannan gums, cellulose and cellulose derivatives, starch, starch derivatives, xanthan, derivatized xanthan and mixtures thereof.