Oil recovery process

Abstract

The present invention provides a method for enhancing the recovery of oil from a formation. A hydrocarbon-containing gas and an ether are injected into an oil-bearing formation to mobilize the oil. The mobilized oil is then produced from the formation.

What is claimed is: 
     
         1 . A method for recovering oil from an oil-bearing formation, comprising:
 injecting a hydrocarbon-containing gas comprising at least 70 mol % methane and an ether comprising from 2 to 4 carbon atoms into the formation;   contacting the hydrocarbon-containing gas and the ether with oil in the oil-bearing formation to mix the hydrocarbon-containing gas and the ether with the oil; and   producing oil from the formation.   
     
     
         2 . The method of  claim 1  wherein contacting the hydrocarbon-containing gas and the ether with oil in the oil-bearing formation to mix the hydrocarbon-containing gas and the ether with the oil mobilizes the contacted oil in the formation. 
     
     
         3 . The method of  claim 1  wherein contacting the hydrocarbon-containing gas and the ether with the oil in the oil-bearing formation to mix the hydrocarbon-containing gas and the ether with the oil swells the oil. 
     
     
         4 . The method of  claim 1  wherein contacting the hydrocarbon-containing gas and the ether with the oil in the oil-bearing formation reduces oil-water interfacial tension between oil and water in the formation. 
     
     
         5 . The method of  claim 1  wherein the formation is a subterranean formation. 
     
     
         6 . The method of  claim 5  wherein the subterranean formation is located at a depth of from 200 to 1500 meters. 
     
     
         7 . The method of  claim 1  wherein injecting the hydrocarbon-containing gas and the ether into the formation comprises injecting a mixture of the hydrocarbon-containing gas and the ether into the formation. 
     
     
         8 . The method of  claim 1  wherein at least a portion of the hydrocarbon-containing gas is produced from the formation. 
     
     
         9 . The method of  claim 1  wherein at least a portion of the ether is produced from the formation. 
     
     
         10 . The method of  claim 1  wherein the pressure of the formation at a location in the formation where the hydrocarbon-containing gas and the ether are contacted with the oil in the formation is below the minimum miscibility pressure of the hydrocarbon-containing gas with the oil in the formation. 
     
     
         11 . The method of  claim 10  wherein the pressure of the formation at the location in the formation where the hydrocarbon-containing gas and the ether are contacted with the oil in the formation is above the minimum miscibility pressure of the mixture of the hydrocarbon-containing gas and the ether with the oil. 
     
     
         12 . The method of  claim 1  wherein the oil in the formation has a viscosity of at most 15 cP prior to contact with the hydrocarbon-containing gas and the ether. 
     
     
         13 . The method of  claim 1  wherein a displacement fluid is injected into the formation subsequent to the injection of the hydrocarbon-containing gas and ether into the formation. 
     
     
         14 . The method of  claim 13  wherein the displacement fluid is water. 
     
     
         15 . The method of  claim 1  wherein the ether is dimethyl ether. 
     
     
         16 . The method of  claim 1  wherein the formation has a pressure of at most 45 MPa. 
     
     
         17 . The method of  claim 1  wherein the ether comprises at least 5 mol % of the combined ether and hydrocarbon-containing gas injected into the formation.