Use of foam with in situ combustion process

Abstract

The present invention relates to a novel method of maintaining a steady and/or proper water-gas ratio for the wet in situ combustion process for oil recovery. In particular, the method comprises mixing water with a foaming agent, or some other colloid capable of generating foam, in addition to gas. The foam carries the water through heated reservoirs more efficiently and prevents separation from the gas. As such, more heat can be scavenged, thus an increased amount of steam is generated and transferred to the oil to increase its recovery.

What is claimed is: 
     
         1 . An in situ combustion method of recovery of hydrocarbons from a subterranean oil containing formation penetrated by at least one injection well and at least one production well, which comprises:
 igniting the hydrocarbons to form a combustion front by injecting oxygen-containing gas and heat into the formation through an injection well;   injecting a water through an injection well and in contact with a fluid that is at least one of a foam, an aerosol, a hydrosol, an emulsion and a colloidal dispersion and has a density and viscosity to carry the water via buoyancy forces; and   recovering hydrocarbons and other fluids at a production well.   
     
     
         2 . The method of  claim 1 , wherein the density of the fluid is between 0.000598-0.0770 g/cm 3  and the viscosity is between 0.0123-0.0216 cP. 
     
     
         3 . The method of  claim 1 , further comprising injecting an agent into the injection well to form the fluid in situ. 
     
     
         4 . The method of  claim 3 , wherein said agent is a surfactant. 
     
     
         5 . The foaming agent of  claim 4 , wherein the surfactant is chosen from a group comprising alkyl benzene, aromatic sulfonates, alpha/internal olefin, sulfonates, alkyl aryl sulfonates, alkoxy sulfates or any combination thereof. 
     
     
         6 . The method of  claim 3 , wherein said agent is an alkali-based salt. 
     
     
         7 . The foaming agent of  claim 6 , wherein the alkali-based salt is chosen from a group comprising sodium carbonate, sodium bicarbonate, sodium hydroxide, potassium carbonate, potassium bicarbonate, potassium hydroxide, magnesium carbonate, calcium carbonate or any combination thereof. 
     
     
         8 . The method of  claim 3 , wherein said water containing said agent is injected continuously. 
     
     
         9 . The method of  claim 3 , wherein said water containing the agent is injected into vertical or horizontal wells. 
     
     
         10 . The method of  claim 3 , wherein said water containing said agent is injected in a slug. 
     
     
         11 . The method of claim  0 , wherein said water comprises oilfield brine, produced water, seawater, aquifer water, and riverwater. 
     
     
         12 . The method of  claim 1 , further comprising injecting a non-oxygen containing gas. 
     
     
         13 . The method in  claim 1 , further comprising injecting hydrogen, nitrogen, methane, hydrogen sulfide, propane, butane, natural gas, flue gas, or any combination thereof, and wherein said oxygen-containing gas is air, oxygen, carbon dioxide, carbon monoxide, or any combination thereof. 
     
     
         14 . An in situ combustion method of recovery of hydrocarbons from a Steam Assisted Gravity Drainage (SAGD) depleted reservoir penetrated by at least one injection well and at least one production well, which comprises:
 igniting the hydrocarbons to form a combustion front by injecting oxygen-containing gas and heat into the formation through an injection well;   scavenging heat from a rock formation by injecting a water containing an agent to generate a fluid that is at least one of a foam, an aerosol, a hydrosol, an emulsion and a colloidal dispersion; and,   recovering hydrocarbons and other fluids at a production well.   
     
     
         15 . An improved method of wet in situ combustion oil recovery, the method comprising igniting oil in a formation to form a burning front and injecting water behind said burning front to capture heat and drive oil towards a production well, wherein the improvement comprises injecting water behind said burning front and in contact with a fluid that is at least one of a foam, an aerosol, a hydrosol, an emulsion and a colloidal dispersion and has a density and viscosity to carry the water via buoyancy forces.