System and methods for treating subsurface formations containing fractures

Abstract

Methods of treating hydrocarbon containing formations are described herein. A method for treating a mudstone formation includes providing a substantially horizontal or inclined wellbore to mudstone formation; providing acid to the portion of mudstone formation such that a size of the fractures is increased; and allowing hydrocarbons to flow through the fractures.

What is claimed is: 
     
         1 . A method for treating a mudstone formation, comprising:
 providing a substantially horizontal or inclined wellbore to the mudstone formation;   forming a plurality of fractures in a portion of the mudstone formation, wherein the fractures comprise one or more microfractures having a width of less than 0.5 mm;   providing acid to the portion of mudstone formation such that a width of some of the microfractures increases to a width greater than the original width of the fracture; and   allowing hydrocarbons to flow through the widened fractures.   
     
     
         2 . The method as claimed in  claim 1 , assessing a size and location of fractures in the portion of the mudstone formation. 
     
     
         3 . The method as claimed in any one of  claim 1  or  2 , wherein mudstone formation contains about 10% carbonate minerals. 
     
     
         4 . The method as claimed in any one of  claims 1 - 3 , wherein forming fractures comprises hydraulic fracturing, pneumatic fracturing, alternate fracturing, or combinations thereof. 
     
     
         5 . The method as claimed in any one of  claims 1 - 4 , wherein providing acid etches a surface of the fracture. 
     
     
         6 . The method as claimed in any one of  claims 1 - 5 , further comprising producing hydrocarbons from the mudstone formation. 
     
     
         7 . The method as claimed in any one of  claims 1 - 6 , wherein the mudstone formation comprises from about 5% carbonate compounds to about 70% carbonate compounds. 
     
     
         8 . The method as claimed in any one of  claims 1 - 7 , wherein a majority of the fractures are microfractures. 
     
     
         9 . The method as claimed in any one of  claims 1 - 8 , wherein the acid is provided as an emulsion and/or a foam. 
     
     
         10 . The method as claimed in any one of  claims 1 - 9 , further comprising providing stabilizing chemicals to the mudstone formation. 
     
     
         11 . The method as claimed in any one of  claims 1 - 10 , wherein the acid is provided as a solution of acid and quaternary ammonium salts. 
     
     
         12 . The method as claimed in any one of  claims 1 - 11 , wherein the acid is provided as a solution of inorganic salts. 
     
     
         13 . The method as claimed in any one of  claims 1 - 12 , further comprising applying pressure to the acid, wherein the application of pressure forms additional fractures in the mudstone formation. 
     
     
         14 . The method as claimed in any one of  claims 1 - 13 , wherein providing acid enhances conductivity one or more fractures. 
     
     
         15 . A method for treating a mudstone formation, comprising:
 providing a substantially horizontal or inclined wellbore to the mudstone formation;   providing acid to a portion of the mudstone formation comprising microfractures; and   allowing the acid to flow through the microfractures; and   increasing a size of the microfractures such that hydrocarbons flow through the fractures, wherein the acid inhibits softening of the mudstone formation.   
     
     
         16 . The method as claimed in  claim 15 , assessing a size and location of fractures in the portion of the mudstone formation. 
     
     
         17 . The method as claimed in any one of  claim 15  or  16 , wherein mudstone formation contains about 50% carbonate compounds. 
     
     
         18 . The method as claimed in any one of  claims 15 - 17 , wherein providing acid etches surfaces of the microfractures. 
     
     
         19 . The method as claimed in any one of  claims 15 - 18 , further comprising producing hydrocarbons from the mudstone formation. 
     
     
         20 . The method as claimed in any one of  claims 15 - 19 , wherein the mudstone formation comprises from about 5% carbonate materials to about 70% carbonate materials. 
     
     
         21 . The method as claimed in any one of  claims 15 - 20 , further comprising forming fractures in the portion of the mudstone formation prior to providing acid to the mudstone formation. 
     
     
         22 . The method as claimed in any one of  claims 15 - 21 , wherein the acid is providing as an emulsion and/or a foam. 
     
     
         23 . The method as claimed in any one of  claims 15 - 22 , further comprising providing shale stabilizing chemicals to the mudstone formation. 
     
     
         24 . The method as claimed in any one of  claims 15 - 23 , wherein the acid is provided as a solution of acid and quaternary ammonium salts. 
     
     
         25 . The method as claimed in any one of  claims 15 - 24 , further comprising applying pressure to the acid, wherein the application of pressure forms additional fractures in the mudstone formation. 
     
     
         26 . A method for treating a mudstone formation, comprises:
 providing a substantially horizontal or inclined wellbore to the mudstone formation that has undergone a fracturing process;   providing acid to a portion of the mudstone formation comprising microfractures; and   allowing the acid to flow through the microfractures; and   increasing a size of the microfractures to allow placement of proppant inside of the microfractures.   
     
     
         27 . A method for treating a shale formation, comprising:
 providing a substantially horizontal or inclined wellbore to the shale formation;   forming a plurality of fractures in a portion of the shale formation, wherein the fractures comprise one or more microfractures having a width of less than 0.5 mm;   providing acid to the portion of shale formation such that a width of some of the microfractures increases to a width greater than the original width of the fracture;   allowing hydrocarbons to flow through the widened fractures; and   producing hydrocarbons from the formation.   
     
     
         28 . A method for treating a mudstone formation, comprising:
 providing a substantially horizontal or inclined wellbore to the shale formation;   providing a first fluid to a portion of the mudstone formation such that one or more fractures are formed in the formation;   providing a second fluid to the portion of the mudstone formation, the second fluid comprising acid and having a viscosity less than the viscosity of the first fluid, wherein addition of the second fluid increases a width of one or more formed fractures; and   producing hydrocarbons from the formation.   
     
     
         29 . The method as claimed in  claim 28 , wherein at least one of the widened fractures has a width of less than 0.5 mm. 
     
     
         30 . The method as claimed in any one of  claim 28  or  29 , wherein the second fluid comprises proppants. 
     
     
         31 . The method as claimed in any one of  claims 28 - 31 , further comprising providing a third fluid to the formation after providing the second fluid, wherein the third fluid has a higher viscosity than the second fluid. 
     
     
         32 . A method of treating a hydrocarbon formation comprising:
 forming a plurality of fractures in a portion of the hydrocarbon formation; and   providing acid to the portion of the hydrocarbon formation such that a width of some of the fractures increases to a width greater than the original width of the fracture.