Fracturing method for stimulation of wells utilizing carbon dioxide based fluids

Abstract

A method of fracturing a subterranean formation with a stabilized foamed fracturing fluid comprising from about 50 percent to in excess of about 96 percent by volume of carbon dioxide with the remainder comprising an aqueous liquid and a selected surfactant. The foam is formed in situ by injection of a stabilized liquid-liquid emulsion containing liquid carbon dioxide into a well bore penetrating the formation. The temperature and pressure of the emulsion is controlled to maintain the carbon dioxide in the liquid phase during injection into the well bore. Thereafter, the carbon dioxide is heated by the subterranean formation to a temperature above about 88° F. at which time the stabilized emulsion spontaneously forms a high quality stabilized foam.

What is claimed is: 
     
       1. A method of fracturing a subterranean formation penetrated by a well bore comprising: admixing an aqueous liquid with liquid carbon dioxide and a selected surfactant comprising at least one member selected from the group consisting of alkyl quaternary amines, betaines, sulfated alkoxylates and ethoxylated linear alcohols to form a stabilized emulsion, said emulsion comprising .Iadd.an amount of liquid carbon dioxide whereby upon conversion of said liquid carbon dioxide to a gas and said emulsion to a foam, said foam contains .Iaddend.from about .[.50.]. .Iadd.53 .Iaddend.to in excess of about 96 percent by per volume carbon dioxide and said surfactant being present in said emulsion in an amount sufficient to stabilize said emulsion;   introducing said emulsion into said well bore penetrating said subterranean formation at a temperature below the critical temperature of carbon dioxide and under sufficient pressure to maintain the carbon dioxide as a liquid;   maintaining said emulsion within said formation for a sufficient time to permit said emulsion to be heated to a temperature above the critical temperature of carbon dioxide to form a stabilized foam from said emulsion, said foam having a viscosity immediately after formation which is substantially the same as the viscosity of the emulsion; and   fracturing said subterranean formation with said foam.   
     
     
       2. The method of claim 1 wherein said surfactant is present in a concentration in the range of from about 0.05 percent to about 2.0 percent by weight of the emulsion. 
     
     
       3. The method of claim 1 wherein said emulsion contains a gelling agent comprising a hydratable polymer. 
     
     
       4. A method of claim 1 wherein said emulsion contains a proppant material. 
     
     
       5. The method of claim 4 wherein said proppant is present in an amount of from about 0.5 pound to about 15 pounds per gallon of emulsion. 
     
     
       6. The method of claim 1 wherein said emulsion contains a gelling agent comprising a hydratable polymer in an amount of from about 10 pounds to about 80 pounds per 1,000 gallons of aqueous liquid. 
     
     
       7. A method of fracturing a subterranean formation penetrated by a well bore comprising: admixing an aqueous liquid with a proppant material, liquid carbon dioxide and a selected surfactant comprising at least one member selected from the group consisting of alkyl quaternary amines, betaines, sulfated alkoxylates and ethoxylated linear alcohols to form a stabilized emulsion, said emulsion comprising .Iadd.an amount of liquid carbon dioxide whereby upon conversion of said liquid carbon dioxide to a gas and said emulsion to a foam, said foam contains .Iaddend.from about .[.50.]. .Iadd.53 .Iaddend.to in excess of about 96 percent by volume carbon dioxide and said surfactant being present in said emulsion in an amount sufficient to stabilize said emulsion;   introducing said stabilized emulsion into said well bore penetrating said subterranean formation at a temperature below the critical temperature of carbon dioxide and under sufficient pressure to maintain the carbon dioxide as a liquid;   maintaining said stabilized emulsion within said formation for a sufficient time to permit said emulsion to be heated to a temperature above the critical temperature of carbon dioxide to form a stabilized foam from said emulsion, said foam having a viscosity immediately after formation which is substantially the same as the viscosity of the emulsion;   contacting said formation with said foam at a pressure sufficient to create at least one fracture in said subterranean formation; and   depositing said proppant material in said fracture in said subterranean formation.   
     
     
       8. The method of claim 7 wherein said surfactant is present in a concentration in the range of from about 0.05 percent to about 2.0 percent by weight of the emulsion. 
     
     
       9. The method of claim 7 wherein said emulsion contains a gelling agent comprising a hydratable polymer. 
     
     
       10. The method of claim 7 wherein said proppant is present in an amount of from about 0.5 pound to about 15 pounds per gallon of emulsion. 
     
     
       11. The method of claim 7 wherein said emulsion contains a gelling agent comprising a hydratable polymer in an amount of from about 10 pounds to about 80 pounds per 1,000 gallons of aqueous liquid. 
     
     
       12. A method of fracturing a subterranean formation penetrated by a well bore comprising: admixing an aqueous liquid and a gelling agent with liquid carbon dioxide and a selected surfactant to form a stabilized emulsion, said emulsion comprising .Iadd.an amount of liquid carbon dioxide whereby upon conversion of said liquid carbon dioxide to a gas and said emulsion to a foam, said foam contains .Iaddend.from about .[.50.]. .Iadd.53 .Iaddend.to in excess of about 96 percent by volume carbon dioxide and said surfactant being present in said emulsion in an amount sufficient to stabilize said emulsion and said gelling agent comprising a hydratable polymer present in an amount of from about 10 pounds to about 80 pounds per 1000 gallons of aqueous liquid and an inhibitor to retard the hydration rate of the hydratable polymer;   introducing said emulsion into said well bore penetrating said subterranean formation at a temperature below the critical temperature of carbon dioxide and under sufficient pressure to maintain the carbon dioxide as a liquid;   maintaining said emulsion within said formation for a sufficient time to permit said emulsion to be heated to a temperature above the critical temperature of carbon dioxide to form a stabilized foam from said emulsion, said foam having a viscosity immediately after formation which is substantially the same as the viscosity of the emulsion; and   fracturing said subterranean formation with said foam.   
     
     
       13. The method of claim 12 wherein said surfactant comprises at least one member selected from the group consisting of alkyl quaternary amines, betaines, sulfated alkoxylates and ethyoxylated linear alcohols. 
     
     
       14. The method of claim 12 wherein said surfactant is present in a concentration in the range of from about 0.05 percent to about 2.0 percent by weight of the emulsion. 
     
     
       15. A method of fracturing a subterranean formation penetrated by a well bore comprising: admixing an aqueous liquid and a gelling agent comprising a hydratable polymer and an inhibitor to retard the hydration rate of said hydratable polymer with a proppant material, liquid carbon dioxide and a selected surfactant to form a stabilized emulsion, said emulsion comprising .Iadd.an amount of liquid carbon dioxide whereby upon conversion of said liquid carbon dioxide to a gas and said emulsion to a foam, said foam contains .Iaddend.from about .[.50.]. .Iadd.53 .Iaddend.to in excess of about 96 percent by volume carbon dioxide, said surfactant being present in said emulsion in an amount sufficient to stabilize said emulsion and said gelling agent being present in an amount of from about 10 pounds to about 80 pounds per 1000 gallons of aqueous liquid;   introducing said stabilized emulsion into said well bore penetrating said subterranean formation at a temperature below the critical temperature of carbon dioxide and under sufficient pressure to maintain the carbon dioxide as a liquid;   maintaining said stabilized emulsion within said formation for a sufficient time to permit said emulsion to be heated to a temperature above the critical temperature of carbon dioxide to form a stabilized foam from said emulsion, said foam having a viscosity immediately after formation which is substantially the same as the viscosity of the emulsion;   contacting said formation with said foam at a pressure sufficient to create at least one fracture in said subterranean formation; and   depositing said proppant material in said fracture in said subterranean formation.   
     
     
       16. The method of claim 15 wherein said surfactant comprises at least one member selected from the group consisting of alkyl quaternary amines, betaines, sulfated alkoxylates and ethyoxylated linear alcohols. 
     
     
       17. The method of claim 15 wherein said surfactant is present in a concentration in the range of from about 0.05 percent to about 2.0 percent by weight of the emulsion. 
     
     
       18. The method of claim 15 wherein said proppant is present in an amount of from about 0.5 pound to about 15 pounds per gallon of emulsion. .Iadd. 
     
     
       19.  A method of fracturing a subterranean formation penetrated by a well bore comprising: admixing an aqueous liquid with liquid carbon dioxide and a selected surfactant comprising at least one member selected from the group consisting of alkyl quaternary amines, betaines, sulfated alkoxylates and ethoxylated linear alcohols to form a stabilized emulsion, said emulsion comprising from about 67 to about 95 percent by volume carbon dioxide and said surfactant being present in said emulsion in an amount sufficient to stabilize said emulsion;   introducing said emulsion into said well bore penetrating said subterranean formation at a temperature below the critical temperature of carbon dioxide and under sufficient pressure to maintain the carbon dioxide as a liquid;   maintaining said emulsion within said formation for a sufficient time to permit said emulsion to be heated to a temperature above the critical temperature of carbon dioxide to form a stabilized foam from said emulsion, said foam having a viscosity immediately after formation which is substantially the same as the viscosity of the emulsion; and   fracturing said subterranean formation with said foam..Iaddend. .Iadd.   
     
     
       20.  The method of claim 19 wherein said surfactant is present in a concentration in the range of from about 0.05 percent to about 2.0 percent by weight of the emulsion..Iaddend. .Iadd.21. The method of claim 19 wherein said emulsion contains a gelling agent comprising a hydratable polymer..Iaddend. .Iadd.22. The method of claim 21 wherein said emulsion contains a proppant material..Iaddend. .Iadd.23. The method of claim 22 wherein said proppant is present in an amount of from about 0.5 pound to about 15 pounds per gallon of emulsion..Iaddend. .Iadd.24. The method of claim 21 wherein said emulsion contains a gelling agent comprising a hydratable polymer in an amount of from about 10 pounds to about 80 pounds 
     
     
        per 1,000 gallons of aqueous liquid..Iaddend. .Iadd.25.  A method of fracturing a subterranean formation penetrated by a well bore comprising: admixing an aqueous liquid with a proppant material, liquid carbon dioxide and a selected surfactant comprising at least one member selected from the group consisting of alkyl quaternary amines, betaines, sulfated alkoxylates and ethoxylated linear alcohols to form a stabilized emulsion, said emulsion comprising from about 67 to about 95 percent by volume carbon dioxide and said surfactant being present in said emulsion in an amount sufficient to stabilize said emulsion;   introducing said stabilized emulsion into said well bore penetrating said subterranean formation at a temperature below the critical temperature of carbon dioxide and under sufficient pressure to maintain the carbon dioxide as a liquid;   maintaining said stabilized emulsion within said formation for a sufficient time to permit said emulsion to be heated to a temperature above the critical temperature of carbon dioxide to form a stabilized foam from said emulsion, said foam having a viscosity immediately after formation which is substantially the same as the viscosity of the emulsion;   contacting said formation with said foam at a pressure sufficient to create at least one fracture in said subterranean formation; and   depositing said proppant material in said fracture in said subterranean formation..Iaddend. .Iadd.26. The method of claim 25 wherein said surfactant is present in a concentration in the range of from about 0.05 percent to about 2.0 percent by weight of the emulsion..Iaddend. .Iadd.27. The method of claim 25 wherein said emulsion contains a gelling agent comprising a hydratable polymer..Iaddend. .Iadd.28. The method of claim 27 wherein said hydratable polymer is present in said emulsion in an amount of from about 10 pounds to about 80 pounds per 1,000 gallons of aqueous liquid..Iaddend. .Iadd.29. The method of claim 28 wherein said proppant is present in an amount of from about 0.5 pound to about 15 pounds per gallon   
     
     
        of emulsion..Iaddend. .Iadd.30.  A method of fracturing a subterranean formation having a temperature above the critical temperature of carbon dioxide and penetrated by a well bore comprising: admixing an aqueous liquid containing a gelling agent with liquid carbon dioxide and a selected surfactant comprising at least one member selected from the group consisting of alkyl quaternary amines, betaines, sulfated alkoxylates and ethoxylated linear alcohols to form a stabilized emulsion, said emulsion comprising an amount of liquid carbon dioxide whereby upon conversion of said liquid carbon dioxide to a gas and said emulsion to a foam, said foam contains from about 53 to in excess of about 96 percent by volume carbon dioxide and said surfactant being present in said emulsion in an amount sufficient to stabilize said emulsion;   introducing said emulsion into said well bore penetrating said subterranean formation at a temperature below the critical temperature of carbon dioxide and under sufficient pressure to maintain the carbon dioxide as a liquid; and   continuing the introduction of said emulsion into said well bore and into said formation so that said emulsion is heated to a temperature above the critical temperature of carbon dioxide to form a stabilized foam from said emulsion and so that fractures are formed in said subterranean   
     
     
        formation..Iaddend. .Iadd.31.  The method of claim 30 wherein a proppant material is admixed with said aqueous liquid, gelling agent, liquid carbon dioxide and surfactant..Iaddend. .Iadd.32. The method of claim 31 wherein said gelling agent is a hydratable polymer and is present in said emulsion in an amount of from about 10 pounds to about 80 pounds per 1,000 gallons of aqueous liquid in said emulsion..Iaddend. .Iadd.33. The method of claim 32 wherein said surfactant is present in said emulsion in an amount in the range of from about 0.05 percent to about 2.0 percent by weight of said emulsion..Iaddend. .Iadd.34. The method of claim 33 wherein said proppant material is present in said emulsion in an amount of from about 0.5 pound 
     
     
        to about 15 pounds per gallon of emulsion..Iaddend. .Iadd.35.  A method of fracturing a subterranean formation having a temperature above the critical temperature of carbon dioxide and penetrated by a well bore comprising: admixing an aqueous liquid containing a gelling agent with liquid carbon dioxide and a selected surfactant comprising at least one member selected from the group consisting of alkyl quaternary amines, betaines, sulfated alkoxylates and ethoxylated linear alcohols to form a stabilized emulsion, said emulsion comprising from about 67 to about 95 percent by volume carbon dioxide and said surfactant being present in said emulsion in an amount sufficient to stabilize said emulsion;   introducing said emulsion into said well bore penetrating said subterranean formation at a temperature below the critical temperature of carbon dioxide and under sufficient pressure to maintain the carbon dioxide as a liquid; and   continuing the introduction of said emulsion into said well bore and into said formation so that said emulsion is heated to a temperature above the critical temperature of carbon dioxide to form a stabilized foam from said emulsion and so that fractures are formed in said subterranean   
     
     
        formation..Iaddend. .Iadd.36.  The method of claim 35 wherein a proppant material is admixed with said aqueous liquid, gelling agent, liquid carbon dioxide and surfactant..Iaddend. .Iadd.37. The method of claim 36 wherein said gelling agent is a hydratable polymer and is present in said emulsion in an amount of from about 10 pounds to about 80 pounds per 1,000 gallons of aqueous liquid in said emulsion..Iaddend. .Iadd.38. The method of claim 37 wherein said surfactant is present in said emulsion in an amount in the range of from about 0.05 percent to about 2.0 percent by weight of said emulsion..Iaddend. .Iadd.39. The method of claim 38 wherein said proppant is present in said emulsion in an amount of from about 0.5 pound to about 
     
     
        15 pounds per gallon of emulsion..Iaddend. .Iadd.40.  A method of fracturing a subterranean formation having a temperature above the critical temperature of carbon dioxide and penetrated by a well bore comprising: admixing an aqueous liquid, a hydratable polymer gelling agent and a proppant material with liquid carbon dioxide and a selected surfactant to form a stabilized emulsion, said emulsion comprising an amount of liquid carbon dioxide whereby upon conversion of said liquid carbon dioxide to a gas and said emulsion to a foam, said foam contains from about 53 to in excess of about 96 percent by volume carbon dioxide and said surfactant being present in said emulsion in an amount sufficient to stabilize said emulsion;   introducing said stabilized emulsion into said well bore penetrating said subterranean formation at a temperature below the critical temperature of carbon dioxide and under sufficient pressure to maintain the carbon dioxide as a liquid;   continuing the introduction of said emulsion into said well bore and into said formation so that said emulsion is heated to a temperature above the critical temperature of carbon dioxide to form a foam from said emulsion which is stabilized by said surfactant and supports proppant material in a concentration substantially the same as the concentration of the proppant material in said emulsion and so that fractures are formed in said subterranean formation and proppant material is carried into and deposited   
     
     
        in said fractures..Iaddend. .Iadd.41.  The method of claim 40 wherein said surfactant comprises at least one member selected from the group consisting of alkyl quaternary amines, betaines, sulfated alkoxylates and ethoxylated linear alcohols..Iaddend. .Iadd.42. The method of claim 40 wherein said surfactant is present in a concentration in the range of from about 0.05 percent to about 2.0 percent by weight of said emulsion..Iaddend. .Iadd.43. The method of claim 42 wherein said hydratable polymer gelling agent is present in said emulsion in an amount of from about 10 to about 80 pounds per 1,000 gallons of aqueous liquid..Iaddend. .Iadd.44. The method of claim 43 wherein said proppant is present in said emulsion in an amount of from about 0.5 pound to about 15 
     
     
        pounds per gallon of emulsion..Iaddend. .Iadd.45.  A method of fracturing a subterranean formation having a temperature above the critical temperature of carbon dioxide penetrated by a well bore comprising: admixing an aqueous liquid, a hydratable polymer gelling agent and a proppant material with liquid carbon dioxide and a selected surfactant to form a stabilized emulsion, said emulsion comprising from about 67 to about 95 percent by volume carbon dioxide and said surfactant being present in said emulsion in an amount sufficient to stabilize said emulsion;   introducing said stabilized emulsion into said well bore penetrating said subterranean formation at a temperature below the critical temperature of carbon dioxide and under sufficient pressure to maintain the carbon dioxide as a liquid;   continuing the introduction of said emulsion into said well bore and into said formation so that said emulsion is heated to a temperature above the critical temperature of carbon dioxide to form a foam from said emulsion which is stabilized by said surfactant and supports proppant material in a concentration substantially the same as the concentration of the proppant material in said emulsion and so that fractures are formed in said subterranean formation and proppant material is carried into and deposited in said fractures..Iaddend. .Iadd.46. The method of claim 45 wherein said surfactant comprises at least one member selected from the group consisting of alkyl quaternary amines, betaines, sulfated alkoxylates and ethoxylated linear alcohols..Iaddend. .Iadd.47. The method of claim 45 wherein said surfactant is present in a concentration in the range of from about 0.05 percent to about 2.0 percent by weight of said emulsion..Iaddend. .Iadd.48. The method of claim 47 wherein said hydratable polymer gelling agent is present in said emulsion in an amount of from about 10 to about 80 pounds per 1,000 gallons of aqueous liquid..Iaddend. .Iadd.49. The method of claim 48 wherein said proppant is present in said emulsion in an amount of from about 0.5 pound to about 15 pounds per gallon of emulsion..Iaddend.