Enhanced Hydrocarbon Recovery by in Situ Combustion of Oil Sand Formations

Abstract

The present invention is a method and apparatus for the enhanced recovery of petroleum fluids from the subsurface by in situ combustion of the hydrocarbon deposit, from injection of an oxygen rich gas and drawing off a flue gas to control the rate and propagation of the combustion front to be predominantly horizontal and propagating vertically downwards guided by the vertical highly permeable hydraulic fractures. Multiple propped vertical hydraulic fractures are constructed from the well bore into the oil sand formation and filled with a highly permeable proppant containing hydrodesulfurization and thermal cracking catalysts. The oxygen rich gas is injected via the well bore into the top of the propped fractures, the in situ hydrocarbons are ignited by a downhole burner, and the generated flue gas extracted from the bottom of the propped fractures through the well bore and mobile oil gravity drains through the propped fractures to the bottom of the well bore and pumped to the surface. The combustion front is predominantly horizontal, providing good vertical and lateral sweep, due to the flue gas exhaust control provided by the highly permeable propped fractures.

1 - 26 . (canceled) 
   
   
       27 . A method for the in situ recovery of hydrocarbons from a hydrocarbon containing formation, comprising:
 a. drilling a bore hole in the formation to a predetermined depth to define a well bore with a casing;   b. installing one or more vertical proppant and diluent filled hydraulic fractures from the bore hole to create a process zone within the formation by injecting a fracture fluid into the casing;   c. placing a downhole electric pump, a downhole packer, piping, and at least two drop tubes inside the casing, wherein one drop tube is used for flue gas extraction and another drop tube is used for injection of the oxygen rich gas;   d. injecting an oxygen rich gas into a section of the bore hole connected to the hydraulic fractures;   e. igniting the hydrocarbon deposit;   f. exhausting a combustion gas from the formation; and   g. recovering a hydrocarbon from the formation through the piping inside the casing.   
   
   
       28 . The method of  claim 27 , further including the step of installing a top and bottom screen in the casing, wherein a hydraulic connection from the casing well bore to the propped fractures and the oil sand formation is established. 
   
   
       29 . The method of  claim 27 , wherein the oxygen rich gas is injected at the top of the hydraulic fractures through the drop tube, through the top screen, and into the propped fractures. 
   
   
       30 . The method of  claim 27 , wherein the hydrocarbon deposit is ignited by a downhole burner placed inside the casing. 
   
   
       31 . The method of  claim 27 , further including the step of pooling the hydrocarbon at the bottom of the hydraulic fracture, wherein the hydrocarbon enters into the well bore through the lower screen and accumulates at a location adjacent to the downhole electric pump. 
   
   
       32 . The method of  claim 27 , wherein the produced hydrocarbon mixture flows through a hot spent combusted zone. 
   
   
       33 . The method of  claim 27 , wherein flue gas is extracted by the drop tube. 
   
   
       34 . The method of  claim 29 , wherein the injected gas is air. 
   
   
       35 . The method of  claim 29 , wherein the injected gas is a mixture of oxygen and carbon dioxide. 
   
   
       36 . The method of  claim 27 , wherein the combusted gas is separated into carbon dioxide and a fuel gas. 
   
   
       37 . The method of  claim 35 , wherein the carbon dioxide produced is re-injected into the formation. 
   
   
       38 . The method of  claim 27 , wherein the hydraulic fractures are filled with proppants of differing permeability. 
   
   
       39 . The method of  claim 27 , wherein the proppant of the hydraulic fractures contains a catalyst or a mixture of catalysts. 
   
   
       40 . The method of  claim 39 , wherein the catalyst is one of a group of hydrodesulfurization catalysts or thermal cracking catalysts or a mixture thereof. 
   
   
       41 . The method of  claim 27 , wherein a catalyst or mixture of catalysts are placed in a canister in the well bore through which the produced hydrocarbons flow. 
   
   
       42 . The method of  claim 41 , wherein the catalyst is one of a group of hydrodesulfurization catalysts or thermal cracking catalysts or a mixture thereof. 
   
   
       43 . The method of  claim 27 , wherein the pressure in the majority of the part of the process zone is at ambient reservoir pressure. 
   
   
       44 . The method of  claim 27 , wherein at least two vertical fractures are installed from the bore hole at approximately orthogonal directions. 
   
   
       45 . The method of  claim 27 , wherein at least three vertical fractures are installed from the bore hole. 
   
   
       46 . The method of  claim 27 , wherein at least four vertical fractures are installed from the bore hole. 
   
   
       47 . A well in a formation of unconsolidated and weakly cemented sediments, comprising:
 a. a bore hole in the formation to a predetermined depth;   b. an injection casing grouted in the bore hole at the predetermined depth, wherein the injection casing comprises winged initiation sections;   c. a bottom screen and a top screen in said injection casing, whereby the bore hole is capable of hydraulic connection to the propped fractures and the oil sand formation;   d. an electric downhole pump inside of said casing;   e. a cable connected to said electric downhole pump;   f. a downhole packer above said bottom screen inside said casing;   g. a first drop tube for flue gas extraction inside said casing, whereby flue gas can be extracted from said bore hole;   h. a second drop tube for gas injection inside said casing, whereby oxygen enriched gas can be injected into said bore hole;   i. piping inside said casing, whereby hydrocarbons can be produced from said oil sand formation.   j. a source for delivering fracture fluid into the injection casing with sufficient fracturing pressure to dilate the injection casing and the formation and initiate a vertical hydraulic fracture, having a fracture tip, at an azimuth orthogonal to the direction of dilation to create a process zone within the formation, for controlling the propagation rate of a wing of the hydraulic fracture;   k. a source of oxygen rich gas connected to the casing and the propped hydraulic fractures; and
 l. an ignition source for igniting the hydrocarbon deposit in the presence of the oxygen rich gas, wherein a resulting combustion gas from the formation is exhausted through the casing and petroleum hydrocarbons from the formation are recovered through the casing. 
   
   
   
       48 . The well of  claim 47 , wherein the second drop tube is fluidly connected to the top screen. 
   
   
       49 . The well of  claim 47 , wherein the piping is fluidly connected to the bottom screen. 
   
   
       50 . The well of  claim 47 , further comprising an oil pool at the bottom of the hydraulic fracture fluidly connected to the bottom screen and the piping and adjacent the downhole electric pump. 
   
   
       51 . The well of  claim 47 , wherein the injection casing comprises eight symmetrical fracture initiation sections to install two hydraulic fractures on different azimuth planes. 
   
   
       52 . A method for the in situ recovery of hydrocarbons from a hydrocarbon containing formation, comprising:
 a. drilling a bore hole in the formation to a predetermined depth to define a well bore with a casing;   b. installing one or more vertical proppant and diluent filled hydraulic fractures from the bore hole to create a process zone within the formation by injecting a fracture fluid into the casing;   c. washing the fracture fluid from the casing;   d. placing a downhole electric pump, a downhole packer, piping, and at least two drop tubes inside the casing, wherein one drop tube is used for flue gas extraction and another drop tube is used for injection of the oxygen rich gas;   e. injecting an oxygen rich gas at ambient reservoir pressure through a drop tube inside the casing and through a top screen in the casing fluidly connected to the hydraulic fractures;   f. igniting the injected gas with a downhole burner;   g. igniting the hydrocarbons in the formation in the vicinity of the injected gas to create a combustion front;   h. draining the heated oil by gravity into the bottom of the hydraulic fracture and through a bottom screen in the casing fluidly connected to the hydraulic fracture;   i. controlling the propagation rate and growth of the combustion front by varying the extraction rate of the flue gas; and   j. recovering a hydrocarbon from the formation through the bottom screen through tubing inside the casing fluidly connected to the bottom screen.