Enhanced hydrocarbon recovery from a single well by electrical resistive heating of multiple inclusions in an oil sand formation

Abstract

The present invention is a method and apparatus for enhanced recovery of petroleum fluids from the subsurface by electrical resistive heating of the oil sand formation and the heavy oil and bitumen in situ, by electrically energizing vertical inclusion planes containing electrically conductive proppant. The inclusion is propagated into a portion of the formation having a Skempton's B parameter of greater than 0.95 exp(−0.04 p′)+0.008 p′, where p′ is a mean effective stress in MPa at the depth of the inclusion. Multiple propped vertical inclusions at various azimuths are constructed from the well. Electrodes are placed in the well in electrical contact with the inclusions and an alternating direction current is passed through the proppant. By electrically resistive heating of the inclusion, the formation is heated by conduction and associated hydrocarbon fluids are lowered in viscosity and drain by gravity back to the well and produced to the surface. By controlling the reservoir temperature and pressure, a particular fraction of the in situ hydrocarbon reserve is extracted and water inflow into the heated zone is minimized.

1 . A method of improving production of hydrocarbons from a subterranean formation of weakly cemented sediments, the method comprising the steps of:
 a) propagating a substantially vertical first inclusion into the formation in a first preferential direction from a substantially vertical wellbore intersecting the formation, wherein the first inclusion is filled with an injected fluid including electrically conductive proppant particles;   b) passing an electric current through the inclusion by electrodes placed in the wellbore and heating the formation in a process zone in the vicinity of the first inclusion; and   c) producing the heated hydrocarbons up the wellbore from the formation.   
     
     
         2 . The method of  claim 23 , wherein the method includes propagating a plurality of second inclusions initiated from the same wellbore at progressively shallower depths after the viscosity of the injected fluid in the immediate lower inclusion has substantially reduced, wherein the plurality of second inclusions intersect and coalesce with the inclusion immediately beneath the last of the second inclusions, and with the electric current passing through all inclusions. 
     
     
         3 . The method of  claim 23 , wherein the method includes propagating a plurality of first inclusions at varying azimuths and a plurality of second inclusions at the same varying azimuths. 
     
     
         4 . The method of  claim 3 , wherein the method includes propagating a plurality of second inclusions initiated from the same wellbore at progressively shallower depths after the viscosity of the injected fluid in the immediately lower inclusion has substantially reduced, wherein the plurality of second inclusions intersect and coalesce with the inclusion immediately beneath the last of the second inclusions on its respective azimuth, and wherein the electric current passes through all inclusions. 
     
     
         5 . The method of  claim 1 , wherein the proppant particles range in size from #4 to #100 U.S. mesh and are ceramic beads substantially coated with an electrically conductive resin. 
     
     
         6 . The method of  claim 5 , wherein the resin is phenol formaldehyde containing fine graphite particles and is heat hardenable, with resin present in an amount sufficient to consolidate the proppant, but insufficient to fill the openings between the proppant. 
     
     
         7 . The method of  claim 1 , wherein the proppant particles of range in size from #4 to #100 U.S. mesh and are selected from a group of conductive materials such as metals, melt alloys, metal oxides, metal salts, metal-containing catalysts, calcined petroleum coke or graphite beads, green or black silicon carbide, boron carbide or a mixture thereof. 
     
     
         8 . The method of  claim 1 , wherein the proppant particles ranging in size from #4 to #100 U.S. mesh and are selected from a group of non-conductive materials such as ceramics, glass and sands coated with a conductive layer either being metal, metal oxide, metal salts, conductive resins or mixtures thereof. 
     
     
         9 . The method of  claim 1 , wherein pressure in a majority of the heated process zone is held at ambient reservoir pressure by injecting into the process zone steam, non-condensing gas or a hydrocarbon solvent in a vaporized state or a mixture thereof. 
     
     
         10 . The method of  claim 9 , wherein the solvent is one of a group of ethane, propane, butane or a mixture thereof. 
     
     
         11 . The method of  claim 9 , wherein the solvent is mixed with a diluent gas. 
     
     
         12 . The method of  claim 11 , wherein the diluent gas is non-condensable under. 
     
     
         13 . The method of  claim 12 , wherein the non-condensable diluent gas has a lower solubility in the formation than the saturated hydrocarbon solvent. 
     
     
         14 . The method of  claim 13 , wherein the diluent gas is one of a group of methane, nitrogen, carbon dioxide, natural gas or a mixture thereof. 
     
     
         15 . The method of  claim 1 , wherein the method further includes injecting a hydrogenising gas into the wellbore and thus into the fluids in the process zone to promote hydrogenation and thermal cracking reactions for at least a portion of the hydrocarbons in the process zone. 
     
     
         16 . The method of  claim 15 , wherein the hydrogenising gas consists of one of the group of H2 and CO or a mixture thereof. 
     
     
         17 . The method of  claim 15 , wherein the method further includes catalyzing the hydrogenation and thermal cracking reactions of at least a portion of the hydrocarbons in the process zone. 
     
     
         18 . The method of  claim 17 , wherein a metal-containing catalyst is used to catalyze said hydrogenation and thermal cracking reactions. 
     
     
         19 . The method of  claim 18 , wherein the catalyst is contained in a canister in tubing inside of the wellbore. 
     
     
         20 . The method of  claim 1 , wherein the proppant particles in the first inclusion includes a catalyst for hydrogenation and thermal cracking reactions within the process zone. 
     
     
         21 . The method of  claim 2 , wherein the proppant particles placed in the middle depth inclusions, excluding the uppermost and lowermost inclusions, have an electrical conductivity that ranges from low to high as the lateral distance increases of the placed proppant particles from the wellbore. 
     
     
         22 . The method of  claim 4 , wherein the proppant particles placed in the middle depth inclusions, excluding the uppermost and lowermost inclusions, have an electrical conductivity that ranges from low to high as the lateral distance increases of the placed proppant particles from the wellbore. 
     
     
         23 . The method of  claim 1 , wherein the method further includes propagating a substantially vertical second inclusion filled with the injected fluid including electrically conductive proppant particles in the same preferential direction as the first inclusion, wherein the second inclusion is initiated after the viscosity of the injected fluid in the first inclusion has substantially reduced and wherein the second inclusion is located above the first inclusion from the same substantially vertical wellbore to intersect and coalesce with the first vertical inclusion in the same formation, and passing an electric current through the first and second inclusions by the electrodes placed in the wellbore, and heating the formation in the process zone in the vicinity of the first and second inclusions. 
     
     
         24 . The method of  claim 1 , wherein a portion of the formation in which the first inclusion is formed has a Skempton B parameter greater than 0.95 exp(−0.04 p′)+0.008 p′, where p′ is a mean effective stress in MPa at the depth of the first inclusion and the water saturation in the formation pores is greater or equal to 10%. 
     
     
         25 . A hydrocarbon production well in a formation of unconsolidated and weakly cemented sediments having an ambient reservoir pressure and temperature comprising:
 a) a substantially vertical bore hole in the formation to a predetermined depth;   b) an injection casing grouted in the bore hole depth to create a substantially vertical wellbore, the injection casing being radially expandable by the introduction of a fluid;   c) a vertical first inclusion in the formation created by the fluid delivered into the injection casing with sufficient pressure to dilate the injection casing and to create the first inclusion in the formation, wherein the first inclusion is filled with the fluid including electrically conductive proppant particles and wherein the first inclusion is oriented in the formation in a first preferential direction extending from and in communication with the substantially vertical wellbore; and   d) electrodes placed in the wellbore for passing an electric current through the inclusion for heating the formation in a process zone in the vicinity of the first inclusion and thereby producing the heated hydrocarbons up the wellbore from the formation.   
     
     
         26 . The production well of  claim 25 , wherein the production well further includes a substantially vertical second inclusion filled with the fluid including electrically conductive proppant particles in the same preferential direction as the first inclusion but initiated after the viscosity of the injected fluid in the first inclusion has substantially reduced and wherein the second inclusion is located above the first inclusion, wherein the second inclusion originates from the same substantially vertical wellbore and intersects and coalesces with the first vertical inclusion in the same formation and the electrodes pass the electric current through the first and second inclusions to heat the formation in the process zone in the vicinity of the first and second inclusions. 
     
     
         27 . The production well of  claim 25 , wherein a portion of the formation having the first inclusion has a Skempton B parameter greater than 0.95 exp(−0.04 p′)+0.008 p′, where p′ is a mean effective stress in MPa at the depth of the first inclusion and the water saturation in the formation pores is greater or equal to 10%. 
     
     
         28 . The production well of  claim 26 , wherein the production well has a plurality of second inclusions initiated from the same wellbore at progressively shallower depths after the viscosity of the injected fluid in the immediate lower inclusion has substantially reduced, wherein the plurality of second inclusions intersect and coalesce with the inclusion immediately beneath the last of the second inclusions, and wherein the electrodes pass the electric current through all inclusions. 
     
     
         29 . The production well of  claim 26 , wherein the production well has a plurality of first inclusions at varying azimuths and a plurality of second inclusions at the same varying azimuths. 
     
     
         30 . The production well of  claim 29 , wherein the production well has a plurality of second inclusions initiated from the same wellbore at progressively shallower depths after the viscosity of the injected fluid in the immediately lower inclusion has substantially reduced, wherein the plurality of second inclusions intersect and coalesce with the inclusion immediately beneath the last of the second inclusions on its respective azimuth, and the electrodes pass the electric current through all inclusions. 
     
     
         31 . The production well of  claim 25 , wherein the proppant particles ranging in size from #4 to #100 U.S. mesh and are ceramic beads substantially coated with an electrically conductive resin. 
     
     
         32 . The production well of  claim 31 , wherein the resin is phenol formaldehyde containing fine graphite particles and is heat hardenable, with resin present in an amount sufficient to consolidate the proppant, but insufficient to fill the openings between the proppant. 
     
     
         33 . The production well of  claim 25 , wherein the proppant particles range in size from #4 to #100 U.S. mesh and are selected from a group of conductive materials such as metals, melt alloys, metal oxides, metal salts, metal-containing catalysts, calcined petroleum coke or graphite beads, green or black silicon carbide, boron carbide or a mixture thereof. 
     
     
         34 . The production well of  claim 25 , wherein the proppant particles range in size from #4 to #100 U.S. mesh are selected from a group of non-conductive materials such as ceramics, glass and sands coated with a conductive layer either being metal, metal oxide, metal salts, conductive resins or mixtures thereof. 
     
     
         35 . The production well of  claim 25 , wherein the production well includes means for injecting steam, non-condensing gas, or a hydrocarbon solvent in a vaporized state or a mixture thereof into the process zone thereby maintaining the pressure in a majority of the heated process zone at ambient reservoir pressure. 
     
     
         36 . The production well of  claim 35 , wherein the solvent is one of a group of ethane, propane, butane or a mixture thereof. 
     
     
         37 . The production well of  claim 35 , wherein the solvent is mixed with a diluent gas. 
     
     
         38 . The production well of  claim 37 , wherein the diluent gas is non-condensable under process conditions. 
     
     
         39 . The production well of  claim 38 , wherein the non-condensable diluent gas has a lower solubility in the formation than the saturated hydrocarbon solvent. 
     
     
         40 . The production well of  claim 39 , wherein the diluent gas is one of a group of methane, nitrogen, carbon dioxide, natural gas or a mixture thereof. 
     
     
         41 . The production well of  claim 25 , wherein the production well further includes means for injecting a hydrogenising gas into the wellbore and thus into the fluids in the process zone to promote hydrogenation and thermal cracking reactions for at least a portion of the hydrocarbons in the process zone. 
     
     
         42 . The production well of  claim 41 , wherein the hydrogenising gas consists of one of the group of H2 and CO or a mixture thereof. 
     
     
         43 . The production well of  claim 42 , wherein the production well further includes means for catalyzing the hydrogenation and thermal cracking reactions of at least a portion of the hydrocarbons in the process zone. 
     
     
         44 . The production well of  claim 43 , wherein a metal-containing catalyst is used to catalyze said hydrogenation and thermal cracking reactions. 
     
     
         45 . The production well of  claim 44 , wherein the catalyst is contained in a canister in tubing inside of the wellbore casing. 
     
     
         46 . The production well of  claim 25 , wherein the proppant particles in the first inclusion includes a catalyst for hydrogenation and thermal cracking reactions within the process zone. 
     
     
         47 . The production well of  claim 28 , wherein the proppant particles placed in the middle depth inclusions, excluding the uppermost and lowermost inclusions, have an electrical conductivity that ranges from low to high as the lateral distance increases of the placed proppant particles from the wellbore. 
     
     
         48 . The production well of  claim 30 , wherein the proppant particles placed in the middle depth inclusions, excluding the uppermost and lowermost inclusions, have an electrical conductivity that ranges from low to high as the lateral distance increases of the placed proppant particles from the wellbore.