Formation pressure testing apparatus with flexible member and method of formation pressure testing

• US 20050011644A1
• Filed: 06/18/2004
• Published: 01/20/2005
• Est. Priority Date: 03/18/2002
• Status: Active Grant

• Current Assignee: Baker Hughes Incorporated (Baker Hughes Company)
• Original Assignee: Baker Hughes Incorporated (Baker Hughes Company)
• Inventors: Krueger, Volker, Bothmann, Gunnar, Krueger, Sven, Meister, Matthias, Herberg, Wolfgang
• Granted Patent: US 7,416,023 B2
• Time in Patent Office: Days
• US Class Current: 166/250.70
• CPC Class Codes: E21B 47/01 Devices for supporting measuring instruments on drill bits, pipes, rods or wirelines; Protecting measuring instruments in boreholes against heat, shock, pressure or the like
• CPC Class Codes: E21B 49/10 using side-wall fluid samplers or testers
• CPC Class Codes: E21B 7/06 Deflecting the direction of boreholes

Abstract

An apparatus and method for use in determining pressure at a formation of interest in-situ. A carrier carrying a tool is conveyed in a borehole. The tool includes a sealing member and a port exposable to the formation of interest. A formation fluid sampling chamber is separated from a hydraulic fluid chamber by a flexible member that allows pressure communication from the fluid sampling chamber to the hydraulic fluid chamber. A sensor senses pressure in the hydraulic fluid for determining pressure in the sampling chamber.

Claims

1. An apparatus for determining in-situ a formation fluid pressure comprising:

a) a sealing member sealing a portion of a borehole wall adjacent a formation;

b) a port exposable to the sealed portion to allow fluid communication between the formation and the port;

c) a first chamber accepting a first fluid communicated from the formation;

d) a second chamber containing a second fluid;

e) a flexible member between the first chamber and the second chamber, the flexible member providing pressure communication between the first chamber and the second chamber, the flexible member preventing fluid communication between the first chamber and the second chamber; and

f) a sensor in communication with the second chamber, the sensor sensing a characteristic of the second fluid, the characteristic being representative of a pressure in the first chamber and the formation fluid pressure.

2. An apparatus according to claim 1, wherein the flexible member comprises an elastomeric sheet including a polymer.

3. An apparatus according to claim 2, wherein the polymer is selected from a synthetic polymer and a natural polymer.

4. An apparatus according to claim 1 further comprising a pump acting on the second fluid in the second chamber, the pump pumping to reduce a pressure in the second chamber below a formation pressure, the reduced pressure in the second chamber being communicated to the first chamber to draw the first fluid into the first chamber.

5. An apparatus according to claim 1, wherein the flexible member flexes from a first position to a second position, the first position resulting in a portion of the flexible member being substantially juxtaposed to the port providing a substantially zero volume in the first chamber.

6. An apparatus according to claim 5, wherein the flexible member flexes from the second position to the first position expelling the first fluid from the first chamber through the port.

7. An apparatus according to claim 1 further comprising a reversible pump operating on the second fluid.

8. An apparatus according to claim 1, wherein the sealing member and the port are on an extendable probe having a probe body and an inner bore for accepting fluid from the formation through the port.

9. An apparatus according to claim 1 further comprising a pump operating on the second fluid and a controller coupled to the pump and to the sensor, the controller controlling the pump in a closed-loop manner based in part on an output signal received from the sensor.

10. An apparatus according to claim 9, wherein the controller controls the pump to reduce a pressurization effect at the port as the seal is pressed against the borehole wall.

11. A method of determining in-situ a formation fluid pressure comprising:

a) conveying a tool to a borehole location adjacent a formation of interest;

b) sealing a portion of the borehole wall at the location;

c) communicating a first fluid from the formation into a first chamber in the tool through a port exposed to the sealed portion of the borehole wall;

d) using a flexible member to separate the first chamber from a second chamber containing a second fluid;

e) communicating pressure from the first chamber to the second chamber through the flexible member; and

f) sensing a characteristic of the second chamber using a sensor in communication with the second chamber, the sensed characteristic being representative of a pressure in the first chamber and the formation fluid pressure.

12. A method according to claim 11, wherein the flexible member comprises an elastomeric sheet including a polymer.

13. A method according to claim 12, wherein the polymer is selected from a synthetic polymer and a natural polymer.

14. A method according to claim 11 further comprising using a pump to act on the second fluid in the second chamber and reducing a pressure in the second chamber below the formation fluid pressure using the pump, the reduced pressure being communicated to the first chamber to draw the first fluid into the first chamber.

15. A method according to claim 11 further comprising flexing the flexible member from a first position to a second position, the first position resulting in a portion of the flexible member being substantially juxtaposed to the port providing a substantially zero volume in the first chamber.

16. A method according to claim 15 further comprising expelling the first fluid from the first chamber through the port by flexing the flexible member from the second position to the first position.

17. A method according to claim 11 further comprising using a controller coupled to the sensor to control a pump in a closed-loop manner based in part on an output signal received from the sensor to operate on the second fluid.

18. A method according to claim 17 further comprising controlling the pump with the controller to reduce a pressurization effect at the port as the seal is pressed against the borehole wall.

19. A system for use in conducting a drilling operation, the drilling operation including determining in-situ a formation fluid pressure, the system comprising:

a) a carrier carrying a tool into a well borehole, the tool including;

i) a sealing member sealing a portion of a borehole wall adjacent a formation;

ii) a port exposable to the sealed portion to allow fluid communication between the formation and the port;

iii) a first chamber accepting a first fluid communicated from the formation;

iv) a second chamber containing a second fluid;

v) a flexible member between the first chamber and the second chamber, the flexible member providing pressure communication between the first chamber and the second chamber, the flexible member preventing fluid communication between the first chamber and the second chamber; and

vi) a sensor in communication with the second chamber, the sensor sensing a characteristic of the second fluid;

b) a pump within the carrier operating on the fluid in the second chamber; and

c) a controller including a processor processing an output of the sensor, the processed output being representative of pressure in the first chamber and the flrmation fluid pressure.

20. A system according to claim 19, wherein the flexible member comprises an elastomeric sheet comprising a polymer.

21. A system according to claim 20, wherein the polymer is selected from a synthetic polymer and a natural polymer.

22. A system according to claim 19, wherein the pump operates to reduce a pressure in the second chamber below the formation fluid pressure, the reduced pressure being communicated to the first chamber to draw the first fluid into the first chamber.

23. A system according to claim 19, wherein the flexible member flexes from a first position to a second position, the first position resulting in a portion of the flexible member being substantially juxtaposed to the port providing a substantially zero volume in the first chamber.

24. A system according to claim 23, wherein the flexible member flexes from the second position to the first position expelling the first fluid from the first chamber through the port.

25. A system according to claim 19, wherein the pump is a reversible pump.

26. A system according to claim 19, wherein the sealing member and the port are on an extendable probe having a probe body and an inner bore for accepting the first fluid from the formation through the port.

27. A system according to claim 19, wherein the controller controls the pump in a closed-loop manner based in part on the processed output.

28. A system according to claim 27, wherein the controller controls the pump to reduce a pressurization effect at the port as the seal is pressed against the borehole wall.