Chemomechanical treatment fluids and methods of use

Abstract

Methods and systems are provided for favorably altering the chemomechanical properties of subterranean formations using treatment fluids comprising surfactants and halide salts. Methods for treating formations comprise the steps of introducing a chemomechanical treatment fluid into the formation and allowing the treatment fluid to interact with the formation to alter its petrochemical properties in various ways. Depending on the application, the chemomechanical treatment fluid may comprise a base fluid, a halide salt and an amphoteric or nonamphoteric surfactant where the surfactant is dissolved in the base fluid at a concentration below its critical micelle concentration. Applications of use involving the chemomechanical treatment fluids include treatment operations, secondary recovery operations, drilling operations, and any other operation that would benefit from the formation property modifications described herein. Subterranean formation properties that may to be varied by the chemomechanical treatment fluid include fracture toughness, compressive strength, and tensile strength.

What is claimed is: 
     
         1 . A method for treating a subterranean formation comprising:
 (a) providing a chemomechanical treatment fluid comprising a base fluid, a nonamphoteric surfactant, and a halide salt, wherein the nonamphoteric surfactant is dissolved in the base fluid at a concentration below its critical micelle concentration;   (b) introducing the chemomechanical treatment fluid under pressure into the subterranean formation, the subterranean formation having a plurality of fractures, tensile strengths, compressive strengths, and a fracture toughness, wherein each fracture has one or more fracture tips;   (c) substantially ceasing the introduction of the chemomechanical treatment fluid;   (d) allowing the chemomechanical treatment fluid to saturate the fracture tips;   (e) allowing the chemomechanical treatment fluid to interact with the subterranean formation to decrease the tensile strengths, compressive strengths, and fracture toughness of the subterranean formation; and   (f) introducing additional chemomechanical treatment fluid after step (d) under pressure to bifurcate the fracture tips so as to from multiple fractures from each fracture.   
     
     
         2 . The method of  claim 1  wherein the base fluid comprises an aqueous fluid and wherein the nonamphoteric surfactant comprises quaternary ammonium cation surfactant. 
     
     
         3 . The method of  claim 1  wherein the base fluid comprises an aqueous fluid and wherein the nonamphoteric surfactant is ammonium laurel sulfate, sodium lauryl sulfate, or sodium dodecyl sulfate. 
     
     
         4 . The method of  claim 1  wherein the base fluid comprises water and an alcohol and wherein the nonamphoteric surfactant comprises a cationic fluorinated surfactant. 
     
     
         5 . The method of  claim 2  wherein the concentration of the quaternary ammonium cation surfactant in base fluid is from about 100 ppm to about 250 ppm. 
     
     
         6 . The method of  claim 5  wherein the subterranean formation comprises a limestone or a sandstone formation. 
     
     
         7 . The method of  claim 6  wherein the subterranean formation is a low permeability formation, having a permeability of less than about 100 mD before step (b). 
     
     
         8 . The method of  claim 7  wherein the halide salt is a chloride salt or a bromide salt. 
     
     
         9 . The method of  claim 8  wherein step (f) follows step (d) with a minimum time delay of at least about 1 hour between steps (f) and (d). 
     
     
         10 . The method of  claim 1  wherein the base fluid comprises an aqueous fluid, wherein the nonamphoteric surfactant comprises a fluorinated surfactant. 
     
     
         11 . The method of  claim 1  wherein the halide salt is a chloride salt or a bromide salt. 
     
     
         12 . The method of  claim 1  further comprising repeating steps (b) through (f) a plurality of times. 
     
     
         13 . A method for treating a subterranean formation comprising:
 (a) providing a chemomechanical treatment fluid comprising a base fluid, an amphoteric surfactant, and a halide salt, wherein the amphoteric surfactant is dissolved in the base fluid at a concentration below its critical micelle concentration;   (b) introducing the chemomechanical treatment fluid into the subterranean formation;   (c) allowing the chemomechanical treatment fluid to interact with the subterranean formation to increase the tensile strengths, compressive strengths, and fracture toughness of the subterranean formation to form a treated portion of the subterranean formation; and   (d) drilling a portion of a well bore in the treated portion of the subterranean formation.   
     
     
         14 . The method of  claim 13  wherein the base fluid comprises an aqueous fluid and wherein the amphoteric surfactant comprises an amphoteric flourinated surfactant. 
     
     
         15 . The method of  claim 14  wherein the concentration of the amphoteric flourinated surfactant in the base fluid comprises is from about 100 ppm to about 250 ppm. 
     
     
         16 . The method of  claim 13  wherein the step (b) further comprises introducing the chemomechanical treatment fluid into the well bore. 
     
     
         17 . The method of  claim 15  wherein the subterranean formation comprises a limestone or a sandstone formation. 
     
     
         18 . The method of  claim 13  wherein the subterranean formation is a low permeability formation, having a permeability of less than about 100 mD before step (b). 
     
     
         19 . The method of  claim 17  wherein the halide salt is a chloride salt or a bromide salt. 
     
     
         20 . The method of  claim 19  wherein step (f) follows step (d) with a minimum time delay of at least about 1 hour between steps (f) and (d). 
     
     
         21 . The method of  claim 19  wherein step (f) follows step (d) with a minimum time delay of from about 15 minutes to about 1 hour between steps (f) and (d). 
     
     
         22 . The method of  claim 13  wherein the base fluid comprises an aqueous fluid and wherein the amphoteric surfactant comprises a fluorinated surfactant. 
     
     
         23 . The method of  claim 13  wherein the halide salt is a chloride salt or a bromide salt. 
     
     
         24 . An enhanced hydrocarbon recovery method comprising:
 providing a chemomechanical treatment fluid comprising an aqueous base fluid, a surfactant, and a halide salt, wherein the surfactant is dissolved in the aqueous base fluid at a concentration below its critical micelle concentration;   introducing the chemomechanical treatment fluid into the subterranean formation by way of an injection well;   allowing the chemomechanical treatment fluid to interact with the subterranean formation to decrease the tensile strengths, compressive strengths, and fracture toughness of the subterranean formation; and   sweeping hydrocarbons towards a production well using the chemomechanical treatment fluid as a driving fluid for motivating the hydrocarbons towards the production well.   
     
     
         25 . The method of  claim 24  wherein the surfactant is an amphoteric surfactant and wherein the halide salt comprises an iodide salt. 
     
     
         26 . The method of  claim 24  wherein the subterranean formation is a limestone or a sandstone formation. 
     
     
         27 . A chemomechanical treating fluid for treating subterranean formations comprising:
 an aqueous base fluid wherein the aqueous base fluid comprises water and an alcohol;   a nonamphoteric surfactant wherein the nonamphoteric surfactant is dissolved in the aqueous base fluid at a concentration below its critical micelle concentration; and   a halide salt.   
     
     
         28 . The method of  claim 27  wherein the nonamphoteric surfactant comprises a nonionic fluorinated surfactant. 
     
     
         29 . The method of  claim 28  wherein the nonamphoteric surfactant comprises an amine oxide based fluorinated surfactant. 
     
     
         30 . The method of  claim 29  wherein the concentration of ammonium laurel sulfate in the base fluid is from about 100 ppm to about 250 ppm. 
     
     
         31 . The method of  claim 30  wherein the halide salt is a chloride salt or a bromide salt.