Recovery of oil sands bitumen

Abstract

A method for improving the SWAG process for extracting the hydrocarbon, bitumen, from tar sands by injecting carbon dioxide into the reservoir. Said carbon dioxide will dissolve in the bitumen producing a solution having increased producibility greatly above that of the native bitumen. Recovery of the bitumen CO2 solution can be further enhanced by heat. Heat can be supplied by various means including elevating the temperature of the carbon dioxide prior to injection, injecting a mixture of carbon dioxide and steam or generating heat in-situ by including oxygen, preferably purified, with any of the above-mentioned injectants. This invention is ideally conducted through, but not limited to, the use of horizontal wells completed near the top and base of the reservoir.

What is claimed is: 
     
         1 . A process for increasing the production of bitumen from an oil sand reservoir by the injection of carbon dioxide into one or more wells penetrating said oil sand. 
     
     
         2 . A process described in  claim 1  wherein the injection of carbon dioxide is followed by the injection of steam containing little or no carbon dioxide. 
     
     
         3 . A process described in  claim 1  wherein purified oxygen is injected to produce carbon dioxide in situ. 
     
     
         4 . A process described in  claim 1  wherein the injectant is a mixture of carbon dioxide and steam. 
     
     
         5 . A process described in  claim 1  wherein the injectant is a mixture of carbon dioxide, steam, and oxygen. 
     
     
         6 . A process described in  claim 1  wherein purified oxygen is injected to produce carbon dioxide in situ following the injection of carbon dioxide or steam. 
     
     
         7 . A process described in  claim 1  wherein the carbon dioxide is heated to above 100 degrees Fahrenheit prior to injection. 
     
     
         8 . A process for enhancing the production of bitumen from a reservoir wherein carbon dioxide is injected near the top of the reservoir to decrease the bitumen viscosity and provide a portion of the energy required to displace the bitumen to one or more production wells located in the reservoir below the injection wells. 
     
     
         9 . A process for stimulating a new injection well consisting of injecting carbon dioxide into said injection well and then back producing the well to enhance the formation of a steam chest on subsequent steam injection cycles. 
     
     
         10 . A process described in  claim 9  wherein the carbon dioxide is injected in ad mixture with steam.