Formation evaluation system and method

• US 20060000603A1
• Filed: 09/02/2005
• Published: 01/05/2006
• Est. Priority Date: 06/28/2002
• Status: Active Grant

• Current Assignee: Schlumberger Technology Corporation (Schlumberger NV)
• Original Assignee: Schlumberger Technology Corporation (Schlumberger NV)
• Inventors: Vasques, Ricardo, Zazovsky, Alexander F., Campo, Christopher S. Del
• Granted Patent: US 7,484,563 B2
• Time in Patent Office: Days
• US Class Current: 166/244.100
• CPC Class Codes: E21B 49/10 using side-wall fluid samplers or testers

Abstract

A method of evaluating a fluid from a subterranean formation drawn into a downhole tool positioned in a wellbore penetrating the subterranean formation is provided. The method involves drawing fluid from a formation into an evaluation flowline, drawing fluid from a formation into a cleanup flowline, measuring a property of the fluid in the evaluation flowline and detecting stabilization of the property of the fluid in the evaluation flowline. Fluid properties in a combined flowline may be generated from the evaluation and cleanup flowlines. The fluid properties of the combined flowline may be used to project future evaluation flowline fluid properties. Contamination levels for a given fluid property of a given flowline may also be determined.

Claims

1. A method of evaluating a fluid from a subterranean formation drawn into a downhole tool positioned in a wellbore penetrating the subterranean formation, comprising:

drawing fluid from a formation into an evaluation flowline;

drawing fluid from a formation into a cleanup flowline;

measuring a property of the fluid in the evaluation flowline; and

detecting stabilization of the property of the fluid in the evaluation flowline.

2. The method of claim 1 further comprising measuring a property of the fluid in the cleanup flowline.

3. The method of claim 2 further comprising verifying stabilization by detecting an increase in the fluid property in the cleanup flowline during stabilization.

4. The method of claim 1 further comprising establishing a combined flowline from the evaluation and cleanup flowlines and measuring a property of the combined flowline.

5. The method of claim 4 further comprising detecting an increase in the fluid property in the combined flowline.

6. The method of claim 1 wherein the fluid property is optical density.

7. The method of claim 1 further comprising converting the fluid property to a contamination level.

8. The method of claim 1 further comprising taking at least one derivative of the measured property of the evaluation flowline.

9. The method of claim 1, wherein stabilization occurs when the property of the evaluation flowline at two successive points is substantially the same.

10. The method of claim 1, wherein stabilization occurs when a derivative of the property of the evaluation flowline at two successive points is equal to zero.

11. The method of claim 1, further comprising calibrating at least one sensor of the downhole tool, the at least one sensor adapted to measure the property of the flowlines.

12. The method of claim 1, further establishing a combined flowline from the evaluation and cleanup flowlines and estimating at least one future fluid property for the combined flowline.

13. The method of claim 12, further comprising estimating at least one future fluid property of an evaluation flowline from the at least one future fluid property of the combined flowline.

14. The method of claim 13, further comprising determining a time when the at least one future fluid property of the evaluation flowline reaches a target property level.

15. The method of claim 12, further comprising determining a fluid property of one of the evaluation flowline, the cleanup flowline, the combined flowline and combinations thereof.

16. The method of claim 15, further comprising determining a contamination level corresponding to the determined fluid property.

17. A method of evaluating a fluid from a subsurface formation drawn into a downhole tool positioned in a wellbore penetrating the subterranean formation, comprising:

drawing fluid from the formation into an evaluation flowline;

drawing fluid from a formation into a cleanup flowline;

generating a combined flowline from the evaluation and cleanup flowlines;

determining a virgin fluid break through property (Pmf) and a virgin fluid property (Pvf) for the combined flowline;

measuring at least one fluid property of one of the evaluation flowline, the cleanup flowline, the combined flowline and combinations thereof; and

determining a contamination level for the at least one fluid property from the virgin fluid breakthrough parameter (Pmf), the virgin fluid property (Pvf) and the measured fluid property (Pd).

18. The method of claim 17, wherein Pmf is determined by measuring at least one property of the fluid prior to the break through of virgin fluid.

19. The method of claim 17, wherein Pvf is determined based on combined fluid models.

20. The method of claim 17, wherein the combined flowline is generated by combining fluid in the evaluation and cleanup flowlines.

21. The method of claim 17, wherein the combined flowline is generated by mathematically determining combined flowline from the evaluation and cleanup flowlines.

22. The method of claim 17, further comprising estimating at least one future fluid property of the combined flowline.

23. The method of claim 22, further comprising estimating at least one future fluid property of an evaluation flowline from the at least one future fluid property of the combined flowline.

24. The method of claim 23, further comprising determining a time when the at least one future fluid property of the evaluation flowline reaches a target property level.

25. The method of claim 17, further comprising calibrating at least one sensor of the downhole tool, the at east one sensor adapted to measure the property of the flowlines.

26. The method of claim 17, further comprising determining the stabilization of the property of the fluid in the evaluation flowline.

28. The method of claim 17, wherein the combined flowline is generated by combining fluid in the evaluation and cleanup flowlines.

29. The method of claim 17, wherein the combined flowline is generated by mathematically determining combined fluid properties from the evaluation and cleanup flowlines.

30. The method of claim 17, further comprising detecting stabilization of the property of the fluid in the evaluation flowline.

31. The method of claim 30 further comprising measuring at least one property of the fluid in the cleanup flowline.

32. The method of claim 31 further comprising verifying stabilization by detecting an increase in the fluid property in the cleanup flowline.

33. The method of claim 30 further comprising establishing a combined flowline from the evaluation and cleanup flowlines and measuring a property of the combined flowline.

34. The method of claim 33 further comprising detecting an increase in the fluid property in the combined flowline.

35. The method of claim 30 wherein the fluid property is optical density.

36. The method of claim 30 further comprising converting the fluid property to a contamination level.

37. The method of claim 30 further comprising taking at least one derivative of the measured property of the evaluation flowline.

38. The method of claim 30, wherein stabilization occurs when the property of the evaluation flowline at two successive points is substantially the same.

39. The method of claim 30, wherein stabilization occurs when a derivative of the property of the evaluation flowline at two successive points is equal to zero.

40. The method of claim 30, further comprising calibrating at least one sensor of the downhole tool, the at least one sensor adapted to measure the property of the flowlines.

27. A method of evaluating a fluid from a subsurface formation drawn into a downhole tool positioned in a wellbore penetrating the subterranean formation, comprising:

drawing fluid from the formation into an evaluation flowline;

drawing fluid from a formation into a cleanup flowline;

generating a combined flowline from the evaluation and cleanup flowlines;

determining at least one initial fluid property of the fluid in the combined flowline for an initial period of time;

estimating at least one projected combined parameter of the fluid for a future period of time for the combined flowline;

estimating at least one projected evaluation parameter of the fluid for the evaluation flowline for the future period of time based on the estimated projected combined parameter; and

determining the time when the projected evaluation parameter reaches a target contamination level.