Method for enhanced oil recovery from carbonate reservoirs

Abstract

Method of using direct current (DC) electrokinetics to enhance oil production from carbonate reservoirs The method comprising the steps of selecting an underground formation comprising an Oil-bearing carbonate reservoir, positioning two or more electrically conductive elements at spaced apart locations in proximity to said formation, at least one of said conductive elements being disposed in or adjacent to a bore hole affording fluid communication between the interior of said bore hole and said formation, passing a controlled amount of electric current along an electrically conductive path through said formation, said electric current being produced by a DC source including a cathode connected to one of said conductive elements and an anode connected to another of said conductive elements, said electrically conductive path comprising at least one of connate formation water and an aqueous electrolyte introduced into said formation, and withdrawing oil from at least one of said bore holes.

1 . A method of enhancing oil recovery from a carbonate reservoir comprising the steps of:
 a. selecting an underground formation comprising an oil-bearing carbonate reservoir;   b. positioning two or more electrically conductive elements at spaced apart locations in proximity to said formation, at least one of said conductive elements being disposed in or adjacent to a bore hole affording fluid communication between the interior of said bore hole and said formation;   c. passing a controlled amount of electric current along an electrically conductive path through said formation, said electric current being produced by a DC source including a cathode connected to one of said conductive elements and an anode connected to another of said conductive elements, said electrically conductive path comprising at least one of connate formation water and an aqueous electrolyte introduced into said formation; and   d. withdrawing oil from at least one of said bore holes.   
     
     
         2 . The method of  claim 1 , wherein the electrically conductive element to which said cathode is connected is disposed in a bore hole from which oil is withdrawn. 
     
     
         3 . The method of  claim 1  further including the step of superimposing an AC component on the DC current to effect decomposition of the withdrawn oil and a decrease in the viscosity thereof. 
     
     
         4 . The method of  claim 1 , wherein said formation undergoes an acidizing pre-treatment to increase permeability of said formation. 
     
     
         5 . A method of fracturing an oil-bearing carbonate rock formation, said method comprising subjecting said formation to long term electrical stress. 
     
     
         6 . The method of  claim 5 , wherein said electrical stress is applied to said formation by means comprising:
 a. positioning two or more electrically conductive elements at spaced apart locations in proximity to said formation; and   b. passing a controlled amount of electric current along an electrically conductive path through said formation, said electric current being produced by a DC source including a cathode connected to one of said conductive elements and an anode connected to another of said conductive elements, said electrically conductive path comprising at least one of connate formation water and an aqueous electrolyte introduced into said formation.   
     
     
         7 . The method of  claim 6 , wherein said electrical stress is applied for a time period ranging from 1 day to 12 months.