Reduced contamination sampling

• US 6,668,924 B2
• Filed: 11/01/2002
• Issued: 12/30/2003
• Est. Priority Date: 11/14/2000
• Status: Expired due to Term

• Current Assignee: Schlumberger Technology Corporation (Schlumberger NV)
• Original Assignee: Schlumberger Technology Corporation (Schlumberger NV)
• Inventors: Brown, Jonathan W., Bolze, Victor M.
• Primary Examiner(s): Bagnell, David
• Assistant Examiner(s): Gay, Jennifer Hawkins
• Application Number:
  US10/065,603
• Publication Number:
  US 20030042021A1
• Time in Patent Office: 424 Days
• Field of Search: 166/264, 166/163, 166/165, 166/167, 175/20, 175/58, 175/59
• US Class Current: 166/264
• CPC Class Codes: E21B 49/0815 Sampling valve actuated by tubing pressure changes
• CPC Class Codes: E21B 49/082 Wire-line fluid samplers E21B49/083 takes precedence

Abstract

A downhole sampling tool and related method are provided. The tool is provided with a main flowline for communicating fluid from the formation through the tool. A main valve is positioned in the main flowline and defines a first portion and a second portion of the main flowline. At least one sample chamber with a slidable piston therein defining a sample cavity and a buffer cavity is also provided. The sample cavity is in selective fluid communication with the first portion of the main flowline via a first flowline and with the second portion of the main flowline via a second flowline. Fluid communication is selectively established between the sample cavity and the first and/or second portions of the main flowline for selectively flushing fluid through the sample cavity and/or collecting samples of the fluid therein. Fluid may also be discharged from the buffer cavity via a third flowline.

Claims

1. A downhole sampling tool positionable in a wellbore penetrating a subterranean formation, comprising:

a main flowline extending through the downhole tool for conunonicating fluid obtained from the formation through the downhole tool;

a main valve in the main flowline movable betwecn a closed and an open position, the valve defining a first portion and a second portion of the main flowline;

at least one sample chamber have a slidable piston therein defining a sample cavity and a buffer cavity, the sample cavity in selective fluid communication with the first portion of the main flowline via a first flowline and in selective fluid communication with the second portion of the main flowline via a second flowline;

wherein when the main valve is in the closed position, fluid communication is selectively established between the sample cavity and one of the first portion of the main flowline, the second portion of the main flowline and combinations thereof.

2. The downhole sampling tool of claim 1 further comprising a first valve in the first flowline, the valve movable between a closed position and an open position for selectively allowing fluid communication between the first portion of the main flowline and the sample cavity.

3. The downhole sampling tool of claim 2 further comprising a second valve in the second flowline, the valve movable between a closed position and an open position for selectively allowing fluid communication between the second portion of the main flowline and the sample cavity.

4. The downhole sampling tool of claim 3 wherein when the main valve is in the closed position, the first valve is in the open position and the second valve is in the closed position, fluid flows from the first portion of the main flowline into the sample cavity whereby a sample is collected.

5. The downhole sampling tool of claim 3 wherein when the main valve is in the closed position, the first valve is in the closed position and the second valve is in the open position, fluid flows from the second portion of the main flowline into the sample cavity whereby a sample is collected.

6. The downhole sampling tool of claim 3 wherein when the main valve is closed and the first and second valves are open, fluid flows through the first portion of the main flowline, the first flowline, the sample cavity, the second flowline and the second portion of the main flowline whereby fluid is flushed therefrom.

7. The downhole sampling tool of claim 3 wherein when the main valve is closed and the first and second valves are open, fluid flows through the second portion of the main flowline, the second flowline, the sample cavity, the first flowline and the first portion of the main flowline whereby fluid is flushed therefrom.

8. The downhole sampling tool of claim 3 wherein when the main valve is open and the first and second valves are closed, fluid flows through the first and second portions of the main flowline whereby the fluid bypasses the at least one sample chamber.

9. The downhole sampling tool of claim 1 wherein the buffer cavity is in fluid communication with the borehole via a third flowline.

10. The downhole sampling tool of claim 9 wherein the third flowline is in fluid communication with one of the first and second portion of the main flowline via the third flowline.

11. The downhole sampling tool of claim 9 wherein the third flowline is in selective fluid communication with one of the first and second portion of the main flowline via the third flowline.

12. The downhole sampling tool of claim 11 further comprising a third valve in the third flowline, the valve movable between a closed position and an open position for selectively allowing fluid communication between the main flowline and the buffer cavity.

13. The downhole sampling tool of claim 1 wherein the at least one sample chamber comprises a plurality of sample chambers.

14. The downhole sampling tool of claim 13 wherein the at least one sample chambers are fluidly connected in series.

15. The downhole sampling tool of claim 13 wherein the at least one sample chambers are fluidly connected in parallel.

16. The downhole sampling tool of claim 1 wherein the downhole tool is modular.

17. The downhole sampling tool of claim 1 further comprising a pump assembly for drawing fluid from the formation into the main flowline.

18. The downhole sampling tool of claim 1 further comprising a pressurization system for charging the buffer cavity to control the pressure of the collected sample fluid in the sample cavity via the floating piston.

19. The downhole sampling tool of claim 1 further comprising a probe assembly for establishing fluid communication between the apparatus and the formation when the apparatus is positioned in the wellbore.

20. A method for obtaining fluid from a subsurface formation penetrated by a wellbore, comprising:

positioning a formation testing apparatus within the wellbore, the testing apparatus comprising a sample chamber having a floating piston slidably positioned therein so as to define a sample cavity and a buffer cavity;

establishing fluid communication between the apparatus and the formation;

inducing movement of fluid from the formation through a main flowline in the apparatus;

diverting fluid from the main flowline into the sample cavity via a first flowline;

discharging fluid from the sample cavity via a second flowline whereby fluid is flushed from the sample cavity; and

terminating the discharge of fluid from the sample cavity whereby a sample is collected in the sample cavity.

21. The method of claim 20, further comprising terminating the flow of fluid from the main flowline into the sample cavity whereby the fluid bypasses the sample chamber.

22. The method of claim 20 wherein a valve is positioned in the main flowline defining a first and second portion of the main flowline, the valve movable between an open and closed position.

23. The method of claim 22 wherein the step of diverting comprises diverting fluid from the first portion of the main flowline into the sample cavity via the first flowline.

24. The method of claim 23 wherein the step of discharging fluid comprises discharging fluid from the sample cavity into the second portion of the main flowline via a second flowline whereby fluid is flushed from the sample cavity.

25. The method of claim 22, further comprising discharging fluid from the buffer cavity into the second portion or the main flowline via a third flowline.

26. The method of claim 20, further comprising discharging fluid from the buffer cavity into the borehole.

27. The method of claim 22 wherein the step of diverting comprises sclectively establishing fluid communication between the sample cavity and the first portion of the main flowline via the first flowline.

28. The method of claim 27 wherein the step of discharging comprises selectively establishing fluid communication between the sample cavity and the second portion of the main flowline via the second flowline whereby fluid is flushed from the sample cavity.

29. A downhole sampling tool positionable in a wellbore penetrating a subterranean formation, comprising:

a probe assembly for establishing fluid communication between the apparatus and the formation when the apparatus is positioned in the wellbore;

a pump assembly for drawing fluid from the formation into the apparatus via said probe assembly;

a main flowline extending through the downhole tool for communicating fluid obtained from the formation through the downhole tool;

a main valve in the main flowline movable between a closed and an open position, the valve defining a first portion and a second portion of the main flowline; and

a sample module for collecting a sample of the formation fluid drawn from the formation by said pumping assembly, said sample module comprising;

at least one sample chamber have a slidable piston therein defining a sample cavity and a buffer cavity, the sample cavity in selective fluid communication with the first portion of the main flowline via a first flowline and in selective fluid communication with the second portion of the main flowline via a second flowline;

wherein when the main valve is in the closed position, fluid communication is selectively established between the sample cavity and one of the first portion of the main flowline, the second portion of the main flowline and combinations thereof.

30. The downhole sampling tool of claim 29, further comprising a pressurization system for charging the pressurization cavity to control the pressure of the collected sample fluid in the sample cavity via the piston.