Method and system for increasing oil production from an oil well producing a mixture of oil and gas

• US 6,032,737 A
• Filed: 04/07/1998
• Issued: 03/07/2000
• Est. Priority Date: 04/07/1998
• Status: Expired due to Term

• Current Assignee: Conocophillips Company (ConocoPhillips)
• Original Assignee: Atlantic Richfield Company (BP PLC)
• Inventors: Klein, John M., Hearn, David D., Stevenson, Mark D., Brady, Jerry L., Cawvey, James L.
• Primary Examiner(s): NEUDER, WILLIAM P
• Application Number:
  US09/056,272
• Time in Patent Office: 700 Days
• Field of Search: 166/265, 166/266, 166/267, 166/268, 166/169, 166/306, 166/106
• US Class Current: 166/265
• CPC Class Codes: E21B 43/385 by reinjecting the separated materials into an earth formation in the same well

Abstract

A method and system for increasing oil production from an oil well producing a mixture of oil and gas at an elevated pressure through a wellbore penetrating an oil-bearing formation containing an oil-bearing zone and an injection zone, by separating at least a portion of the gas from the mixture of oil and gas to produce a separated gas and an oil-enriched mixture; utilizing energy from at least a portion of the mixture of oil and gas to compress at a surface at least a portion of the separated gas to produce a compressed gas having sufficient pressure to be injected into the injection zone; injecting the compressed gas into the injection zone; and recovering at least a major portion of the oil-enriched mixture.

Claims

1. A method for increasing oil production from an oil well producing a mixture of oil and gas at an elevated pressure through a wellbore penetrating an oil-bearing formation containing an oil-bearing zone and an injection zone, the method comprising:

a) separating at least a portion of the gas from the mixture of oil and gas in an auger separator to produce a separated gas and an oil-enriched mixture;

b) utilizing energy from at least a portion of the mixture of oil and gas to compress at a surface at least a portion of the separated gas to produce a compressed gas having sufficient pressure to be injected into the injection zone;

c) injecting the compressed gas into the injection zone; and

d) recovering at least a major portion of the oil-enriched mixture.

2. The method of claim 1 wherein the wellbore is a first wellbore and the step of injecting comprises injecting the compressed gas through a second wellbore into the injection zone.

3. The method of claim 1 further comprising the step of porting the separated gas into an annulus in the oil well for recovery of the separated gas at the surface.

4. The method of claim 1 wherein the step of injecting comprises injecting the compressed gas through the oil well into the injection zone.

5. The method of claim 1 wherein the at least a portion of the mixture of oil and gas is the oil-enriched mixture, and the step of utilizing energy further comprises:

driving a turbine with at least a portion of the oil-enriched mixture;

driving a compressor with the turbine; and

compressing with the compressor the at least a portion of the separated gas to produce the compressed gas.

6. The method of claim 1 wherein the at least a portion of the mixture of oil and gas is the separated gas, and the step of utilizing energy further comprises:

driving a turbine with a first portion of the separated gas;

driving a compressor with the turbine; and

compressing with the compressor a second portion of the separated gas to produce the compressed gas.

7. The method of claim 1 wherein the at least a portion of the mixture of oil and gas is the oil-enriched mixture, the separated gas is a first separated gas, and the step of utilizing energy further comprises:

separating gas from the oil-enriched mixture to produce a second separated gas;

driving a turbine with the second separated gas;

driving a compressor with the turbine; and

compressing with the compressor at least a portion of the first separated gas to produce the compressed gas.

8. The method of claim 1 wherein the at least a portion of the mixture of oil and gas is the oil-enriched mixture, the separated gas is a first separated gas, and the step of utilizing energy further comprises:

separating gas from the oil-enriched mixture to produce a second separated gas;

heating the second separated gas to produce a heated second separated gas;

driving a turbine with the heated second separated gas;

driving a compressor with the turbine; and

compressing with the compressor at least a portion of the first separated gas to produce the compressed gas.

9. The method of claim 1 wherein the at least a portion of the mixture of oil and gas is the oil-enriched mixture, the separated gas is a first separated gas, and the step of utilizing energy further comprises:

separating gas from the oil-enriched mixture to produce a second separated gas;

passing the second separated gas through a heat exchange relation with the compressed gas to produce a heated second separated gas;

driving a turbine with the heated second separated gas;

driving a compressor with the turbine; and

compressing with the compressor at least a portion of the first separated gas to produce the compressed gas.

10. The method of claim 1 wherein the at least a portion of the mixture of oil and gas is the oil-enriched mixture, the separated gas is a first separated gas, and the step of utilizing energy further comprises:

separating gas from the oil-enriched mixture to produce a second separated gas;

driving a turbine with the second separated gas;

driving a first stage compressor with the turbine; and

compressing at least a portion of the first separated gas with the first stage compressor and a second stage compressor to produce the compressed gas.

11. The method of claim 1 wherein the at least a portion of the mixture of oil and gas is the oil-enriched mixture, the separated gas is a first separated gas, and the step of utilizing energy further comprises:

separating gas from the oil-enriched mixture to produce a second separated gas;

passing the second separated gas through a heat exchange relation with the compressed gas to produce a heated second separated gas;

driving a turbine with the heated second separated gas;

driving a first stage compressor with the turbine; and

compressing at least a portion of the first separated gas with the first stage compressor and a second stage compressor to produce the compressed gas.

12. The method of claim 1 wherein the at least a portion of the first mixture of oil and gas is the separated gas, and the step of utilizing energy further comprises:

driving a turbine with the separated gas and discharging from the turbine a product mixture of oil and gas;

driving a compressor with the turbine;

separating at least a portion of the gas from the product mixture of oil and gas to produce a product separated gas;

compressing the product separated gas with the compressor to produce the compressed gas.

13. The method of claim 1 wherein the at least a portion of the first mixture of oil and gas is the separated gas, and the step of utilizing energy further comprises:

driving a turbine with the separated gas and discharging from the turbine a product mixture of oil and gas;

driving a first stage compressor with the turbine;

separating at least a portion of the gas from the product mixture of oil and gas to produce a product separated gas; and

compressing the product separated gas with the first stage compressor and a second stage compressor to produce the compressed gas.

14. The method of claim 1 wherein the at least a portion of the first mixture of oil and gas is the separated gas, and the step of utilizing energy further comprises:

driving a turbine with the separated gas and discharging from the turbine a product mixture of oil and gas;

driving a first stage compressor with the turbine;

separating at least a portion of the gas from the product mixture of oil and gas to produce a product separated gas;

compressing the product separated gas with the first stage compressor and a second stage compressor to produce the compressed gas; and

heating the separated gas by passing the separated gas through a heat exchange relation with the compressed gas.

15. The method of claim 1 wherein the at least a portion of the first mixture of oil and gas is the separated gas, and the step of utilizing energy further comprises:

driving a turbine with the separated gas and discharging from the turbine a product mixture of oil and gas;

driving a compressor with the turbine;

separating at least a portion of the gas from the product mixture of oil and gas to produce a product separated gas;

compressing the product separated gas with the compressor to produce the compressed gas; and

heating the product separated gas by passing the product separated gas through a heat exchange relation with the compressed gas.

16. A system for increasing the production of oil from an oil well producing a mixture of oil and gas at an elevated pressure through a wellbore penetrating a formation containing an oil-bearing zone and an injection zone, the system comprising:

an auger separator in fluid communication with the oil-bearing zone;

a turbine positioned at a surface of the earth and having an inlet in fluid communication with the separator for receiving fluids from the separator for driving the turbine; and

a compressor drivingly connected to the turbine and positioned on the surface, the compressor having a gas inlet in fluid communication with a separated gas discharge outlet on the separator, the compressor further having a compressed gas discharge outlet in fluid communication through a passageway with the injection zone.

17. The system of claim 16 wherein the wellbore is a first wellbore and the passageway is a second wellbore.

18. The system of claim 16 wherein the wellbore is a first wellbore, the passageway is a second wellbore, and the separator is positioned in a tubing string in the first wellbore and is in fluid communication with an annulus formed between the tubing string and the first wellbore, which annulus is in fluid communication with the surface.

19. The system of claim 16 wherein the wellbore is a first wellbore, the passageway is a second wellbore, and the separator is positioned in a tubing string in the first wellbore and is in fluid communication with an annulus formed between the tubing string and the first wellbore, which annulus is in fluid communication with the surface, and the system further comprises a tubular member positioned in the tubing string, a first check valve positioned in the tubular member for permitting fluid flow from the tabular member to the injection zone, and a second check valve positioned in the tubular member for permitting fluid flow from the oil-bearing zone to the tubular member.

20. The system of claim 16 wherein the passageway extends through the wellbore.

21. The system of claim 16 further comprising:

a first tubing string positioned in the wellbore and having a lower tubing string portion in fluid communication with the injection zone and an upper tubing string portion in fluid communication with the surface;

a tubular member positioned in the first tubing string such that a first annulus is formed between the tubular member and the first tubing string, the separator being positioned within the tubular member in fluid communication through the tubular member with the oil-bearing zone;

a second tubing string positioned in the wellbore in fluid communication with the separated gas discharge outlet on the separator and a gas inlet of the compressor;

a first annulus defined between the first and second tubing strings, the first annulus being in fluid communication with an oil-enriched discharge outlet on the separator and with the surface;

a second annulus defined between the first tubing string and the casing, the second annulus being in fluid communication with the compressed gas discharge outlet;

a third annulus defined between first tubing string and the tubular member, the third annulus being in fluid communicator with the injection zone; and

a hole formed in the first tubing string below the separator to permit fluid communication between the second annulus and the third annulus, such that the passageway extends from the compressed gas discharge outlet through the second passageway, through the hole, through the third annulus, and into the injection zone.

22. The system of claim 16 further comprising:

a tubing string positioned in the wellbore and having a lower tubing string portion in fluid communication with the injection zone and an upper tubing string portion in fluid communication with the separator;

a tubular member positioned in the tubing string with a first packer positioned between the tubular member and the tubing string and between the upper and lower tubing string portions, and with a second packer positioned between the tubular member and the wellbore, to provide fluid communication between the oil-bearing zone and the upper tubing portion; and

a hole formed in a wall of the lower tubing string portion, the hole being in fluid communication with a first annulus defined between the tubing string and the wellbore and with a second annulus defined between the tubing string and the tubular member.

23. The system of claim 16 wherein the fluids received from the separator to drive the turbine comprise at least a portion of an oil-enriched mixture.

24. The system of claim 16 wherein the fluids received from the separator to drive the turbine comprise at least a portion of a separated gas.

25. The system of claim 16 wherein the fluids received from the separator to drive the turbine comprise a gaseous portion of an oil-enriched mixture.

26. The system of claim 16 wherein the separator is a first separator, the system further comprising:

a second separator having an inlet connected to receive an oil-enriched mixture from the first separator;

a heater having an inlet connected to receive from the second separator a gaseous portion of the oil-enriched mixture; and

an inlet to the turbine connected to receive from the heater a heated gaseous portion of the oil-enriched mixture for driving the turbine.

27. The system of claim 16 wherein the separator is a first separator, the system further comprising:

a second separator having an inlet connected to receive an oil-enriched mixture produced from the first separator;

a heat exchanger having a first inlet connected to receive from the second separator a gaseous portion of the oil-enriched mixture, and a second inlet connected to receive a compressed gas from the compressor; and

an inlet to the turbine connected to receive from the heat exchanger a heated gaseous portion of the oil-enriched mixture for driving the turbine.

28. The system of claim 16 wherein the separator is a first separator, the compressor is a first stage compressor, and the system further comprising:

a second separator having an inlet connected to receive an oil-enriched mixture from the first separator;

a second stage compressor connected to receive a first compressed gas from the first stage compressor; and

an inlet to the turbine connected to receive from the second separator a gaseous portion of the oil-enriched mixture for driving the turbine.

29. The system of claim 16 wherein the separator is a first separator, the compressor is a first stage compressor, and the system further comprising:

a second separator having an inlet connected to receive an oil-enriched mixture from the first separator;

a second stage compressor connected to receive a first compressed gas from the first stage compressor;

a heat exchanger having a first inlet connected to receive from the second separator a gaseous portion of the oil-enriched mixture, and a second inlet connected to receive a compressed gas from the second stage compressor; and

an inlet to the turbine connected to receive from the heat exchanger a heated gaseous portion of the oil-enriched mixture for driving the turbine.

30. The system of claim 16 wherein the separator is a first separator, the compressor is a first stage compressor, and the system further comprises:

a second stage compressor connected to receive a first compressed gas from the first stage compressor;

a heat exchanger having a first inlet connected to the separated gas discharge outlet on the first separator to receive the separated gas from the first separator, and a second inlet connected to receive a second compressed gas from the second stage compressor;

an inlet to the turbine connected to receive from the heat exchanger a heated separated gas for driving the turbine; and

a second separator having an inlet connected to receive gas and liquids from the turbine and having a gas outlet in fluid communication with an inlet to the first compressor.

31. The system of claim 16 wherein the separator is a first separator and the compressor is a first stage compressor, the system further comprising:

a second stage compressor connected to receive a first compressed gas from the first stage compressor;

an inlet to the turbine connected to receive the separated gas from the first separator for driving the turbine; and

a second separator having an inlet connected to receive gas from the turbine and having a gas outlet in fluid communication with an inlet to the first compressor.

32. The system of claim 16 wherein the separator is a first separator, the system further comprising:

a heat exchanger having a first inlet connected to the separated gas discharge outlet on the first separator to receive the separated gas from the first separator, and a second inlet connected to receive compressed gas from the compressor;

an inlet to the turbine connected to receive from the heat exchanger a heated separated gas for driving the turbine; and

a second separator having an inlet connected to receive gas from the turbine and having a gas outlet in fluid communication with an inlet to the first compressor.

33. The system of claim 16 wherein the separator is a first separator, the system further comprising:

an inlet to the turbine connected to the separated gas discharge outlet on the first separator to receive the separated gas from the first separator for driving the turbine; and

a second separator having an inlet connected to receive gas from the turbine and having a gas outlet in fluid communication with an inlet to the first compressor.