Formation testing apparatus and method for optimizing draw down

• US 20040026125A1
• Filed: 04/25/2003
• Published: 02/12/2004
• Est. Priority Date: 07/20/2001
• Status: Active Grant

• Current Assignee: Baker Hughes Incorporated (Baker Hughes Company)
• Original Assignee: Baker Hughes Incorporated (Baker Hughes Company)
• Inventors: Niemeyer, Eick, Lee, Jaedong, Krueger, Sven, Meister, Matthias
• Granted Patent: US 7,011,155 B2
• Time in Patent Office: Days
• US Class Current: 175/50
• CPC Class Codes: E21B 49/008 by injection test; by analysing pressure variations in an injection or production test, e.g. for estimating the skin factor measuring pressure E21B47/06
• CPC Class Codes: E21B 49/08 Obtaining fluid samples or testing fluids, in boreholes or wells
• CPC Class Codes: E21B 49/0875 determining specific fluid parameters

Abstract

A method and apparatus for of determining a formation parameter of interest. The method includes placing a tool into communication with the formation to test the formation, determining a first formation characteristic during a first test portion, initiating a second test portion, the second test portion having test parameters determined at least in part by the determinations made during the first test portion, determining a second formation characteristic during the second test portion, and determining the formation parameter from one of the first formation characteristic and the second formation characteristic. The apparatus includes a draw down unit and a control system for closed loop control of the draw down unit. A microprocessor in the control system processes signals from a sensor in the draw down unit to determine formation characteristics and to determine test parameters for subsequent test portions.

Claims

1. A method of determining in situ a desired formation parameter of interest comprising:

a) conveying a tool into a well borehole traversing a formation;

b) placing the tool into communication with the formation to test the formation, the test including a first test portion and a second test portion;

c) determining a first characteristic during the first test portion;

d) initiating the second test portion, the second test portion having test parameters determined at least in part by the determinations made during the first test portion;

e) determining a second characteristic during the second test portion; and

f) determining the desired formation parameter from one or more of the first characteristic and the characteristic.

2. The method of claim 1, wherein the first test portion includes increasing a test volume in the tool at a first rate for a predetermined time interval.

3. The method of claim 2, wherein the first test portion includes a multi-rate draw down.

4. The method of claim 3, wherein the multi-rate draw down includes a step-wise draw down.

5. The method of claim 2, wherein the first test portion includes drawing the test volume pressure below the formation pressure and controlling the draw rate to create substantial equilibrium between the draw rate and flow rate into the tool

6. The method of claim 1, wherein the first test portion includes determining one or more of i) formation mobility;

ii) formation pressure;

iii) fluid compressibility; and

iv) a quality indicator.

7. The method of claim 1, wherein the second test portion includes increasing a test volume in the tool at a second rate for a predetermined time interval.

8. The method of claim 7, wherein the second test portion includes a multi-rate draw down.

9. The method of claim 8, wherein the multi-rate draw down includes a step-wise draw down.

10. The method of claim 7, wherein the second test portion includes drawing the test volume pressure below the formation pressure and controlling the draw rate to create substantial equilibrium between the draw rate and flow rate into the tool.

11. The method of claim 1, wherein the second test portion includes determining one or more of i) formation mobility;

ii) formation pressure;

iii) fluid compressibility; and

iv) a quality indicator.

12. The method of claim 1, wherein the first test portion includes increasing a test volume in the tool at a first rate for a predetermined time period, holding the test volume at a constant volume to allow a test volume pressure to stabilize, the test parameters for the second test portion including a second rate for increasing the test volume, the second rate not equaling the first draw rate.

13. The method of claim 1, wherein the second test portion includes aborting the test, wherein the desired formation parameter is determined based in part on the determined characteristic.

14. The method of claim 1, wherein formation rate analysis is used in determining the first characteristic.

15. The method of claim 1, wherein formation rate analysis is used in determining the second characteristic.

16. A method of determining in situ a desired formation parameter of interest comprising:

a) conveying a tool into a well borehole traversing a formation;

b) determining a formation characteristic with the tool;

c) determining a quality indicator by analyzing the determined formation characteristic; and

d) using the quality indicator to verify the determined formation characteristic, wherein the verified formation characteristic is indicative of the desired formation parameter.

17. The method of claim 16, wherein determining the formation characteristic includes at least one draw down test that includes increasing a test volume at a first rate for a predetermined time interval.

18. The method of claim 17, wherein the draw down test includes a multi-rate draw down.

19. The method of claim 18, wherein the multi-rate draw down includes a step-wise draw down.

20. The method of claim 16, wherein determining the formation characteristic includes determining one or more of i) formation mobility;

ii) formation pressure; and

iii) fluid compressibility.

21. The method of claim 16 further comprising using formation rate analysis for determining the formation characteristic.

22. A method of controlling a down hole test tool apparatus, comprising:

a) conveying the tool into a well borehole traversing a formation;

b) placing the tool into communication with the formation to test the formation;

c) determining one or more characteristics of the tool during a first test portion; and

d) controlling a second test portion by establishing one or more test parameters based at least in part on the characteristics of the tool determined during the first test portion.

23. The method of claim 22, wherein the tool includes a draw down unit having a variable test volume and a member for varying the variable test volume and determining the one or more characteristics of the tool including one or more of i) determining position of the member;

ii) determining speed of the member; and

iii) determining pressure in the variable test volume.

24. The method of claim 22, wherein the tool includes a draw down unit having a variable test volume and a member for varying the variable test volume and controlling a second test portion includes one or more of i) controlling position of the member;

ii) controlling speed of the member; and

iii) controlling pressure in the variable test volume.

25. The method of claim 22, wherein testing the formation includes determining one or more of i) formation mobility;

ii) formation pressure; and

iii) fluid compressibility.

26. The method of claim 25 further comprising using formation rate analysis in testing the formation.

27. An apparatus for determining in situ a desired formation parameter of interest comprising:

a) a tool conveyable into a well borehole traversing a formation;

b) a test unit in the tool, the test unit being adapted for communication with the formation to test the formation, the test including a first test portion and a second test portion;

c) a controller associated with the test unit for controlling test parameters used by the test unit;

d) a device for determining a formation characteristic during the first test portion, wherein the second test portion is conducted using test parameters based in part on the determined formation characteristic, the device further determining a second characteristic during the second test portion; and

e) a processor for determining the desired formation parameter from one or more of the first formation characteristic and the second characteristic.

28. The apparatus of claim 27, wherein the controller controls first test portion by increasing a test volume in the test unit at a first rate for a predetermined time interval.

29. The apparatus of claim 27, wherein the controller controls the first test portion by increasing a test volume in the test unit using a multi-rate draw down.

30. The apparatus of claim 29, wherein the multi-rate draw down includes a step-wise draw down.

31. The apparatus of claim 27, wherein the test unit includes a test volume for receiving fluid from the formation, the controller controlling the first test portion by drawing the test volume pressure below the formation pressure and controlling a draw rate to create substantial equilibrium between the draw rate and a flow rate into the tool.

32. The apparatus of claim 27, wherein the processor is used to determine during the first test portion one or more of i) formation mobility;

ii) formation pressure;

iii) fluid compressibility; and

iv) a quality indicator.

33. The apparatus of claim 28, wherein the controller controls the second test portion by increasing the test volume at a second rate for a predetermined time interval.

34. The apparatus of claim 27, wherein the controller controls the second the test portion by increasing a test volume in the test unit using a multi-rate draw down.

35. The apparatus of claim 34, wherein the multi-rate draw down includes a step-wise draw down.

36. The apparatus of claim 27, wherein the test unit includes a test volume for receiving fluid from the formation, the controller controlling the second test portion by drawing the test volume pressure below the formation pressure and controlling a draw rate to create substantial equilibrium between the draw rate and a flow rate into the tool.

37. The apparatus of claim 27, wherein the processor is used to determine during the second test portion one or more of i) formation mobility;

ii) formation pressure;

iii) fluid compressibility; and

iv) a quality indicator.

38. The apparatus of claim 27, wherein the controller controls the second test portion by increasing a test volume in the test unit at a first draw rate for a predetermined time period and holding the test volume at a constant volume to allow a test volume pressure to stabilize, the test parameters for the second test portion including a second draw rate for increasing the test volume, the second draw rate not equaling the first draw rate.

39. A closed-loop controlled test tool for autonomous down hole testing, comprising:

a) a work string for conveying the tool into a well borehole traversing a formation, the tool being adapted for communication with the formation to test the formation;

c) a sensor for determining a characteristic during a first test portion;

d) a controller receiving an output signal from the senor, the controller operating according to one or more programmed instructions to process the received signals to establish one or more test parameters based at least in part on the determined characteristic; and

e) a circuit associated with the controller and the tool for applying the test parameters to a second test portion.

40. The test tool of claim 39, wherein the tool includes a draw down unit having a variable test volume and a member for varying the variable test volume, the determined characteristic being one or more of i) position of the member;

ii) speed of the member; and

iii) pressure in the variable test volume.

41. The test tool of claim 39, wherein the tool includes a draw down unit having a variable test volume and a member for varying the variable test volume, the controller controlling one or more of i) position of the member;

ii) speed of the member; and

iii) pressure in the variable test volume.

42. The test tool of claim 39, wherein the determined characteristic includes one or more of i) formation mobility;

ii) formation pressure;

iii) fluid compressibility; and

iv) a quality indicator.

43. The test tool of claim 39, wherein the controller uses formation rate analysis to test the formation.

44. A system for determining in situ a desired formation parameter of interest comprising:

a) a work string for conveying a tool into a well borehole traversing a formation;

b) a test unit in the tool, the test unit being adapted for communication with the formation to test the formation, the test including a first test portion and a second test portion;

c) a sensor in the tool for determining a first characteristic during the first test portion;

d) a controller receiving an output signal from the senor, the controller operating according to one or more programmed instructions to process the received signals to establish one or more test parameters based at least in part on the determined characteristic;

e) a circuit associated with the controller and the tool for applying the test parameters to a second test portion, the sensor determining a second characteristic during the second test portion; and

f) a processor for processing the first characteristic and the second characteristic to provide processed information, the processed information being indicative of the formation parameter of interest.

45. The system of claim 44, wherein at least one of the first characteristic and the second characteristic is indicative of one or more of i) formation mobility;

ii) formation pressure;

iii) fluid compressibility; and

iv) a quality indicator.

46. The system of claim 44, wherein the tool includes a draw down unit having a variable test volume and a member for varying the variable test volume, at least one of the first characteristic and the second characteristic being indicative of one or more of i) position of the member;

ii) speed of the member; and

iii) pressure in the variable test volume.

47. The system of claim 44, wherein the tool includes a draw down unit having a variable test volume and a member for varying the variable test volume, the controller controlling one or more of i) position of the member;

ii) speed of the member; and

iii) pressure in the variable test volume.