MUD CAKE PROBE EXTENSION

• US 20100186951A1
• Filed: 01/19/2010
• Published: 07/29/2010
• Est. Priority Date: 01/23/2009
• Status: Active Grant

• Current Assignee: Schlumberger Technology Corporation (SLB)
• Original Assignee: Schlumberger Technology Corporation (SLB)
• Inventors: Church, Nathan
• Granted Patent: US 8,499,831 B2
• Time in Patent Office: Days
• US Class Current: 166/264
• CPC Class Codes: E21B 49/10 using side-wall fluid samplers or testers

Abstract

In a formation pressure tester tool, an elongated filter piston possibly having a tapered or sharp edge configured to penetrate mud cake while the probe is being set. At the end of the setting sequence, the filter piston is retracted, thus opening a flowpath from the formation, through the mudcake, to the probe.

Claims

1. An apparatus, comprising:

a downhole tool configured for conveyance within a wellbore extending into a subterranean formation, the downhole tool comprising;

a probe assembly comprising an inlet, a packer comprising an elastomeric material surrounding the inlet, and a filter piston actuatable between an extended position and a retracted position and having an external end, wherein;

the inlet is open when the filter piston is in the retracted position;

the external end substantially closes the inlet when the filter piston is in the extended position; and

the filter piston protrudes from the inlet when the filter piston is in its extended position.

2. The apparatus of claim 1 wherein the external end of the filter piston has a tapered profile.

3. The apparatus of claim 2 wherein the tapered profile has a taper angle ranging between about 30°

and about 120°

.

4. The apparatus of claim 2 wherein the tapered profile has a taper angle ranging between about 70°

and about 100°

.

5. The apparatus of claim 2 wherein the tapered profile has a taper angle of about 90°

.

6. The apparatus of claim 2 wherein the tapered profile tapers to a point.

7. The apparatus of claim 2 wherein the tapered profile tapers to a rounded end.

8. The apparatus of claim 2 wherein the tapered profile tapers to a blunt end.

9. The apparatus of claim 1 wherein the external end of the filter piston is configured to expel filtered particulate from the inlet when translating from the retracted position to the extended position.

10. The apparatus of claim 1 wherein the probe assembly further comprises an actuator configured to translate the filter piston within the inlet between the extended position and the retracted position.

11. The apparatus of claim 1 wherein the probe assembly is configured to measure pressure of the formation surrounding the wellbore when the probe assembly is positioned in engagement with a wall of the wellbore.

12. The apparatus of claim 1 wherein the probe assembly is extendable from the downhole tool for sealing engagement with a mudcake or wall of the wellbore.

13. The apparatus of claim 12 wherein the probe assembly is extendable from the downhole tool via hydraulic, mechanical, electrical, or electromechanical actuation.

14. The apparatus of claim 1 wherein the downhole tool further comprises a controller and circuitry coupling pressure-representative signals from the probe assembly to the controller.

15. The apparatus of claim 1 wherein the downhole tool is configured for conveyance within the wellbore via wireline or drill string.

16. A method, comprising:

positioning a downhole tool within a wellbore extending into a subterranean formation, wherein the downhole tool comprises;

a probe assembly comprising an inlet, a packer comprising an elastomeric material surrounding the inlet, and a filter piston actuatable between an extended position and a retracted position and having an external end, wherein;

the inlet is open when the filter piston is in the retracted position;

the external end substantially closes the inlet when the filter piston is in the extended position; and

the filter piston protrudes from the inlet when the filter piston is in its extended position;

engaging the probe assembly with a wall of the wellbore, such that the inlet is positioned proximate a mudcake lining the wellbore wall;

translating the filter piston from the retracted position towards the extended position, such that the external end of the filter piston extends beyond the inlet to a point embedded within the mudcake.

17. The method of claim 16 wherein engaging the probe assembly with the wall of the wellbore causes the inlet to protrude into the mudcake.

18. The method of claim 16 wherein translating the filter piston causes the external end of the filter piston to extend beyond the mudcake and into the formation.

19. The method of claim 16 further comprising retracting the filter piston to within the probe assembly, thus exposing the inlet to the formation through an opening created by translation of the filter piston, wherein the opening comprises a flowpath from the formation through the mudcake and to the probe assembly.

20. The method of claim 16 further comprising conveying the downhole tool within the wellbore via wireline or drill string.