Methods for Increasing Subterranean Formation Permeability

Abstract

Methods for increasing the permeability of a portion of a subterranean formation surrounding a wellbore using non-hydrolyzed liquid esters to attack carbonates within acid-soluble formations without requiring the use of a catalyst or enzyme. Some methods comprise providing a treatment fluid comprising a non-hydrolyzed liquid ester in a base fluid; introducing the treatment fluid into a subterranean formation at matrix flow rates to allow the non-hydrolyzed liquid ester to penetrate into at least a portion of the subterranean formation; and leaving the treatment fluid in contact with the subterranean formation for a period of time during which at least a portion of the non-hydrolyzed liquid ester hydrolyzes to produce an acid.

1 . A method comprising:
 providing a subterranean formation that has been fractured;   providing a treatment fluid comprising a non-hydrolyzed liquid ester in a base fluid;   introducing the treatment fluid into the fracture at matrix flow rates to allow the non-hydrolyzed liquid ester to penetrate into at least a portion of the subterranean formation surrounding the fracture, wherein the step of introducing the treatment fluid into the fracture at matrix flow rates causes the non-hydrolyzed liquid ester to penetrate into the formation to a depth of at least about 300 cm; and   leaving the treatment fluid in contact with the subterranean formation surrounding the fracture for a period of time during which at least a portion of the non-hydrolyzed liquid ester hydrolyzes to produce an acid.   
     
     
         2 . The method of  claim 1  wherein the non-hydrolyzed liquid ester hydrolyzes to produce an acid without the presence of a catalyst or enzyme. 
     
     
         3 . The method of  claim 1  wherein the non-hydrolyzed liquid ester comprises a formate ester, a lactate ester, and any combination thereof. 
     
     
         4 . The method of  claim 1  wherein the non-hydrolyzed liquid ester comprises diethylene glycol diformate, a glycolate, glycerin triacetate, glycerin diacetate, ethyl lactate, an acetate ester, methyl lactate, ethylene glycol monoformate, an ethyl formate, a methyl formate, and any combination thereof. 
     
     
         5 . (canceled) 
     
     
         6 . The method of  claim 1  wherein the period of time is at least about 2 hours. 
     
     
         7 . The method of  claim 1  wherein the subterranean formation surrounding the fracture has a temperature above about 50° C. and below about 175° C. 
     
     
         8 . The method of  claim 1  wherein the non-hydrolyzed liquid ester is present in the treatment fluid in an amount ranging from about 5% to about 40% by volume of the treatment fluid. 
     
     
         9 . The method of  claim 1  wherein the base fluid is an aqueous fluid. 
     
     
         10 . A method comprising:
 providing a subterranean formation surrounding a wellbore;   providing a treatment fluid comprising a non-hydrolyzed liquid ester in a base fluid;   introducing the treatment fluid into a portion of the subterranean formation surrounding a wellbore at matrix flow rates to allow the non-hydrolyzed liquid ester to penetrate the formation, wherein the step of introducing the treatment fluid into the fracture at matrix flow rates causes the non-hydrolyzed liquid ester to penetrate into the formation to a depth of at least about 300 cm; and   leaving the treatment fluid in contact with the subterranean formation surrounding a wellbore for a period of time during which at least a portion of the non-hydrolyzed liquid ester hydrolyzes to produce an acid.   
     
     
         11 . The method of  claim 10  wherein the non-hydrolyzed liquid ester hydrolyzes to produce an acid without the presence of a catalyst or enzyme. 
     
     
         12 . The method of  claim 10  wherein the non-hydrolyzed liquid ester comprises a formate ester, a lactate ester, and any combination thereof. 
     
     
         13 . The method of  claim 10  wherein the non-hydrolyzed liquid ester comprises diethylene glycol diformate, a glycolate, glycerin triacetate, glycerin diacetate, ethyl lactate, an acetate ester, methyl lactate, ethylene glycol monoformate, an ethyl formate, a methyl formate, and any combination thereof. 
     
     
         14 . (canceled) 
     
     
         15 . The method of  claim 10  wherein the period of time is at least about 2 hours. 
     
     
         16 . The method of  claim 10  wherein the subterranean formation surrounding the fracture has a temperature above about 50° C. and below about 175° C. 
     
     
         17 . The method of  claim 10  wherein the non-hydrolyzed liquid ester is present in the treatment fluid in an amount ranging from about 5% to about 40% by volume of the treatment fluid. 
     
     
         18 . The method of  claim 10  wherein the base fluid is an aqueous fluid.