ELECTRICAL METHOD AND APPARATUS FOR THE RECOVERY OF OIL

• US 3,642,066 A
• Filed: 11/13/1969
• Issued: 02/15/1972
• Est. Priority Date: 11/13/1969
• Status: Expired due to Term

• Current Assignee: William G. Gill
• Original Assignee: William G. Gill
• Inventors: Gill, William G.
• Primary Examiner(s): Calvert, Ian A.
• Application Number:
  US04/876,462
• Time in Patent Office: 824 Days
• Field of Search: 166/248,302,303,52,60
• US Class Current: 166/248
• CPC Class Codes: E21B 43/16 Enhanced recovery methods for obtaining hydrocarbons
• CPC Class Codes: E21B 43/2401 by means of electricity

Abstract

Two well bores extend from the surface into the oil bearing formation defining a producing well and an electrode well. Electrodes in each well, contacting the formation, are connected to a unidirectional current voltage source at the surface through conductive tubing or pipe in the respective well bores to produce a unidirectional voltage gradient between the electrodes, with the producing well poled to be the cathode. Additionally, an alternating current voltage source is connected between the producing well electrode and another conductive path extending from the surface to the formation, to effect the flow of alternating current through the formation adjacent to the producing well to heat the formation.

Claims

1. Apparatus for the recovery of oil from a subsurface oil bearing formation penetrated by at least two well bores including at least one producing well and at least one electrode well comprising:

a first closed loop electrical system for causing the flow of unidirectional current through the formation; and

a second closed loop electrical system for causing the flow of alternating current through the formation;

said unidirectional current closed loop system comprises;

first and second electrode means, each positioned in said producing and electrode wells respectively in electrical contact with the oil-bearing formation, with the electrode means being spaced from each other;

first and second conductor means connected respectively to said first and second electrode means and extending to the surface through the respective well bores; and

a source of unidirectional voltage connected at the surface between said conductor means to produce a unidirectional potential gradient between said first and second electrode means of said unidirectional system, with the first electrode means poled to be a cathode;

said alternating current closed loop system comprising;

said first electrode means positioned in the well bore of the producing well in electrical contact with the oil-bearing formation;

a source of alternating current voltage; and

means including the first conductor means positioned in the producing well for completing an electrical circuit through the formation between the first electrode means and the source of alternating current voltage.

2. Apparatus as set forth in claim 1 wherein said second electrode means and said second conductor means for said unidirectional current system comprise respectively the second electrode means and conductor means for said alternating current system.

3. Apparatus aS set forth in claim 1 wherein each of said electrode means comprises a mass of conductive particles disposed in the bottom of the respective well bores;

wherein the conductor means for each of the well bores extends into the respective mass of conductive particles to make electrical contact therewith; and

including insulating means for insulating each of said conductor means from the walls of respective well bores;

said insulating means extending into the mass of conductive particles to confine the current flow to a path through said conductive particles.

4. Apparatus as set forth in claim 1 wherein each of said electrode means comprises a mass of conductive particles which maintains contact with the formation and is consumable.

5. Apparatus as set forth in claim 1 wherein each of said electrode means for said unidirectional current system comprises a mass of conductive particles disposed in an annular cavity extending laterally from the respective well bores.

6. Apparatus as set forth in claim 1 wherein said first conductor means of the producing well comprises a string of conductive pipe extending from the surface to said first electrode.

7. Apparatus as set forth in claim 1 wherein said first conductor means of the producing well comprises a string of conductive casing and a string of conductive tubing electrically connected in parallel between said first electrode and the surface;

and insulating means comprising an insulating coating provided on the outer wall of said conductive casing.

8. Apparatus for the recovery of oil from a subsurface oil-bearing formation penetrated by two well bores comprising:

first electrode means positioned in a producing well bore in electrical contact with the oil-bearing formation;

first conductor means in said producing well bore extending from said first electrode means to the surface;

insulating means for insulating said first conductor means from the walls of said producing well bore above said first electrode means;

second electrode means positioned in an electrode well bore in electrical contact with the formation;

second conductor means in said electrode well bore extending from said second electrode means to the surface;

insulating means for insulating said second conductor means from the walls of the well bore above said second electrode means;

third electrode means positioned in spaced relation to said first electrode means;

third conductor means extending from said third electrode means to the surface;

a source of unidirectional voltage connected at the surface between said first and second conductor means to provide a unidirectional potential gradient through the formation between said first and second electrode means, with said first electrode means poled to be a cathode;

a source of alternating current supply voltage connected between said first conductor means and said third conductor means to cause the flow of alternating current between said electrodes and through said formation adjacent to said producing well.

9. Apparatus as set forth in claim 8 wherein said first conductor means comprises a string of conductive tubing;

wherein said third electrode means and third conductor means comprise a string of conductive casing placed in said producing well bore extending from the surface toward said formation;

insulating means insulating said string of conductive casing from said electrode to provide a conductive path of substantial length through said formation between said first and third electrode means; and

wherein said first named insulating means comprises a string of insulating casing disposed between said conductive tubing and said conductive casing.

10. Apparatus as set forth in claim 8 wherein said first conductor means comprises a string of conductive casing extending from the first electrode means to the surface;

wherein said insulating means for said conductive casing comprises a coating of insulating material provided on the exterior surfAce of said conductive casing; and

wherein said third electrode means and said third conductor means comprise a string of conductive surface casing enclosing the upper portion of said coated conductive casing.

11. Apparatus for the recovery of oil from a subsurface oil-bearing formation penetrated by two well bores comprising:

first consumable electrode means positioned in a producing well bore comprising a mass of conductive particles urged into a cavity in the formation extending laterally from the well bore;

a first string of electrically conductive pipe in the producing well bore having its lower end connected to said first electrode and having its upper end extending to the surface;

a first string of conductive casing positioned in said producing well bore and provided with an insulating coating for insulating said first string of conductive pipe and said first string of casing from the walls of the well bore above the first electrode means;

means electrically connecting said first string of conductive pipe and said first string of conductive casing to define parallel electrical conductors in said producing well bore between said electrode and the surface;

second consumable electrode means positioned in an electrode well bore comprising a mass of conductive particles urged into a cavity in the formation extending laterally from the well bore;

a second string of electrically conductive pipe in the electrode well bore, having its lower end contacting said second electrode and having its upper end extending to the surface;

a second string of conductive casing positioned in the electrode well bore and provided with an insulating coating for insulating said second string of conductive pipe and said second string of casing from the walls of the electrode well bore;

means electrically connecting said second conductive pipe and said second string of conductive casing to define parallel electrical conductors in the said electrode well bore between said second electrode and the surface; and

a source of unidirectional voltage connected at the surface between said first and second string of conductive pipe to provide a unidirectional potential gradient between said first and second electrodes, with the first electrode in said producing well bore poled to be a cathode.

12. A method for recovering oil from a subsurface oil-bearing formation comprising the steps:

providing at least two spaced-apart well bores defining a producing well and an electrode well;

establishing first electrode means in the formation at the producing well;

establishing second electrode means in the formation at the electrode well;

placing first conductor means in said producing well bore contacting said first electrode and extending to the surface;

placing second conductor means in said electrode well bore contacting said second electrode and extending to the surface;

connecting a source of unidirectional supply voltage between said first and second conductor means, with said first conductor means poled to be a cathode;

insulating said first and second conductor means from the walls of the well bores to cause the flow of unidirectional current between the first and second electrode means through the earth to originate and terminate in the oil-bearing formation; and

connecting a source of alternating current supply voltage between said first conductor means at the surface and another electrode means spaced apart from said first electrode means to cause the flow of alternating current between said first and said another electrode means through said formation in the area of said producing well to heat said formation.

13. A method as set forth in claim 12 including placing surface casing in said producing well bore to define said another electrode means.

14. A method as set forth in claim 13 wherein the source of alternating current supply voltage is connected between said first conductor means And said second conductor means, and said another electrode means is said second electrode means.

15. A method as set forth in claim 12 including establishing said first and second electrode means to extend laterally from the respective well bores to define electrodes having effective diameters substantially greater than those of the respective well bores.