Low Interfacial Tension Systems for Miscible Waterflooding (Patent No: 913349)

Inventor: Froning, H.R.

Location: Tulsa, OK

Comments: N/A

Description: THE EMBODIMENTS OF THE INVENTION IN WHICH AN EXCLUSIVE PROPERTY OR PRIVILEGE IS CLAIMED ARE DEFINED AS FOLLOWS:

1. A water-external micro-emulsion having a water content of from about 85 to about 95 weight percent, the salinity of said water ranging from about 15,000 to about 30,000 ppm, and a solution of from about 5 to about 15 weight percent of an alkali metal oil soluble hydrocarbon sulfonate having an average molecular weight ranging from about 350 to about 475 and a non-acidic preferentially water soluble hydroxylated organic solvent wherein said solvent is present in said solution in a significant amount but in no greater amount than that of the sulfonate employed, the interfacial tension between said emulsion and crude oil being less than 0.1 dyne per cm.

2. A water-external micro-emulsion for use in the displacement of crude oil through an oil bearing formation by means of a liquid flooding operation, said micro-emulsion comprising essentially from about 85 to about 95 weight percent water having a salinity of from about 15,000 to about 25,000 ppm, and a solution of from about 5 to about 15 weight percent of an alkali metal oil soluble hydrocarbon sulfonate having a molecular weight ranging from about 350 to about 475 and a non-acidic preferentially water soluble hydroxylated organic solvent wherein the latter is present in a small but effective amount but in no greater amount than that of the sulfonate employed, the interfacial tension between said emulsion and said crude oil being less than 0.1 dyne per cm.

3. The emulsion of Claim 2 wherein the sulfonate is selected from the group consisting of sodium and ammonium sulfonates.

4. The emulsion of Claim 2 wherein the interfacial tension between said emulsion and said crude oil is no greater than about 0.01 dyne per cm.

5. The emulsion of Claim 3 wherein the sulfonate is a petroleum mahogany sulfonate.

6. The emulsion of Clliaim 3 wherein the sulfonate is an aliphatic hydrocarbon sulfonate.

7. The emulsion of Claim 2 wherein said solvent is a member selected from the group consisting of a c₁ to c₃ alcohol and hexylene glycol.

8. The micro-emulsion of Claim 2 wherein the water content thereof ranges from about 92 to about 95 weight percent and the solution of the sulfonate and said solvent amounts to from about 5 to about 8 weight percent, said sulfonate having an average molecular weight of from about 350 to about 430 and said solvent being selected from the group consisting of a c₁ to c₃ alcohol and hexylene glycol.

9. The emulsion of Claim 8 wherein the water content thereof is about 95 weight percent and the solution of sulfonate and said solvent constitutes the remainder of said emulsion, said sulfonate being a petroleum mahogany sulfonate having an average molecular weight of from about 425 to 430 and said solvent is isopropyl alcohol.

10. A process for recovering oil from a subterranean oil bearing reservoir comprising the steps of injecting into said reservoir through a well therein a quantity of a micro-emulsion of the composition defined in Claim 2, said quantity being sufficient to form in said reservoir a bank of said micro-emulsion, displacing the latter through said reservoir toward a producing well therein, and recovering displaced oil through said producing well.

11. The process of Claim 10 wherein the sulfonate is selected from the group consisting of sodium and ammonium sulfonates.

12. The process of Claim 10 wherein the amount of said micro-emulsion injected is from about 0.02 to about 0.15 pore volume of said reservoir.

13. In the injection of a water stream through an injection well into a porous subsurface formation containing oil which is resistant to displacement by water flow and which substantially restricts the flow of water through the formation, the improvement which comprises removing said oil and thereby increasing the permeability of the formation to water with a resulting substantial increase in the rate of water injection by forcing into the formation through the well bore a micro-emulsion having the composition defined by Claim 2, said micro-emulsion being soluble in water and said oil, continuing the injection of said micro-emulsion to form a continuous liquid with said oil contained therein in a region about the well bore, injecting additional quantities of said micro-emulsion from the well bore sufficient to force the micro-emulsion and oil from the said region in said formation, thereby substantially displacing said oil from said region and thereafter injecting water into said well bore in sufficient quantities to displace said micro-emulsion and saturate the said region in turn with water, and continuing said water injection at a substantially increased permeability.

14. The method of Claim 13 wherein the interfacial tension between said emulsion and said crude oil is no greater than about 0.01 dyne per cm.

15. The method of Claim 13 wherein the sulfonate is selected from the group consisting of sodium and ammonium sulfonates.