Oil recovery by combination steam stimulation and electrical heating

• US 3,946,809 A
• Filed: 12/19/1974
• Issued: 03/30/1976
• Est. Priority Date: 12/19/1974
• Status: Expired due to Term

• Current Assignee: Exxon Production Research Company (Exxon Mobil Corporation)
• Original Assignee: Exxon Production Research Company (Exxon Mobil Corporation)
• Inventors: Hagedorn, Alton R.
• Primary Examiner(s): Novosad, Stephen J.
• Application Number:
  US05/534,261
• Time in Patent Office: 467 Days
• Field of Search: 166/248, 166/303, 166/272, 166/263
• US Class Current: 166/248
• CPC Class Codes: E21B 43/18 Repressuring or vacuum methods
• CPC Class Codes: E21B 43/24 using heat, e.g. steam injection
• CPC Class Codes: E21B 43/2401 by means of electricity

Abstract

Disclosed herein is a method for recovering oil from a subterranean oil-bearing formation in which adjacent wells are subjected to steam stimulation to create a zone around each well which is initially heated to approximately steam temperature and which has a high water saturation following steam injection and oil production. Subsequently, a fluid having a relatively high electrical conductivity, such as a brine solution, is injected into the heated zone around the wells. Preferably the injected volume of high conductivity fluid is sufficient to displace the steam condensate from the zone and to fill the zone with the high conductivity fluid. The wells are then completed as electrodes and current is passed through the formation to heat the oil which was not heated to any significant amount by the steam. Following one or more cycles of steam stimulation and electrical heating, additional oil is recovered from the formation, preferably by line-drive steam displacement or by pattern steam flooding.

Claims

1. A method for recovering oil from a subterranean formation containing oil and connate water and penetrated by a plurality of wells which comprises injecting steam into said formation at each of said wells to heat said formation and said oil contained in said formation, withdrawing heated oil from said formation by means of the same said wells and thereby decreasing the oil saturation in the steam heated portion of said formation and increasing the water saturation within said heated portion of said formation, injecting an electrically conductive fluid into said formation at a volume sufficient to occupy at least a part of the portion of the formation heated by said steam, passing an electrical current between said wells to further heat said formation and said oil contained in said formation, and withdrawing oil from said formation.

2. A method as defined in claim 1 further comprising, subsequent to passing an electrical current between said wells, injecting steam at one of said wells to drive heated oil toward a second of said wells and withdrawing heated oil from said formation by means of said second well.

3. A method as defined in claim 2 further comprising repeating the steps of injecting steam into said formation at each of said wells, withdrawing oil from said formation by means of the same said wells, injecting an electrically conductive fluid into said formation, and passing an electrical current between said wells prior to injecting steam at one of said wells to drive heated oil toward a second of said wells and withdrawing heated oil from said formation by means of said second well.

4. A method as defined in claim 1 wherein the electrically conductive fluid is a brine having a higher electrical conductivity than the connate formation water.

5. A method as defined in claim 4 wherein said brine is heated at the surface prior to injection into said formation.

6. A method as defined in claim 1 wherein the volume of electrically conductive fluid injected into the formation is sufficient to occupy substantially all of the water saturated portion of the steam heated portion of the formation.

7. A method as defined in claim 1 wherein steam is injected concurrently into each of said wells to heat said formation and oil contained in said formation.

8. A method as defined in claim 1 wherein steam is injected into said formation until the steam heated portion of the formation at one well interconnects with the steam heated portion of the formation at a second well.

9. A method as defined in claim 1 wherein each of said wells is fractured prior to injecting an electrically conductive fluid into said formation.

10. A method as defined in claim 1 wherein the electric current is passed between said wells by completing said wells as electrodes and applying alternating current between said wells.

11. A method as defined in claim 1 wherein, during the passage of electrical current between said wells, brine is circulated down each of said wells to cool said wells and to provide electrical contact between said wells and said formation.