OIL RECOVERY PROCESS
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.
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.