Methods for using a formation tester

• US 20050268709A1
• Filed: 05/19/2005
• Published: 12/08/2005
• Est. Priority Date: 05/21/2004
• Status: Active Grant

• Current Assignee: Halliburton Energy Services Incorporated (Halliburton Company)
• Original Assignee: Halliburton Energy Services Incorporated (Halliburton Company)
• Inventors: Stone, James E., Proett, Mark A., Gilbert, Gregory N., Beique, Jean Michel, Welshans, David, Fogal, James M., Marsh, Laban M., McGregor, Malcolm D., Simeonov, Svetozar, Gray, Glenn C.
• Granted Patent: US 7,216,533 B2
• Time in Patent Office: Days
• US Class Current: 73/152.270
• CPC Class Codes: E21B 33/1216 Anti-extrusion means, e.g. means to prevent cold flow of rubber packing
• 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 49/10 using side-wall fluid samplers or testers

Abstract

A method of testing a downhole formation using a formation tester on a drill string. The formation tester is disposed downhole on a drill string and a formation test is performed by forming a seal between a formation probe assembly and the formation. A drawdown piston then creates a volume within a cylinder to draw formation fluid into the volume through the probe assembly. The pressure of the fluid within the cylinder is monitored. The formation test procedure may then be adjusted. The test procedure may be adjusted to account for the bubble point pressure of the fluid being monitored. The pressure may monitored to verify a proper seal is formed or is being maintained. The test procedure may also be performed by maintaining a substantially constant drawdown rate using a hydraulic threshold or a variable restrictor.

Claims

1. A method of testing a downhole formation comprising:

disposing a formation tester on a drill string in a borehole;

performing a formation test procedure with said formation tester comprising;

forming a seal between a formation probe assembly of said formation tester and the formation;

drawing down a drawdown piston to create a volume within a cylinder in said formation tester;

drawing formation fluid into the volume in said cylinder; and

monitoring the pressure within said cylinder; and

adjusting said formation test procedure while said formation tester is in the borehole.

2. The method of claim 1 wherein adjusting said formation test procedure comprises:

transmitting formation test procedure data from said formation tester to the surface;

transmitting formation test procedure commands from the surface to a controller in said formation tester; and

adjusting said formation test procedure with said controller.

3. The method of claim 1 wherein adjusting said formation test procedure comprises:

transmitting formation test procedure data to a controller in said formation tester;

analyzing said formation test procedure data with said controller; and

adjusting said formation test procedure with said controller.

4. The method of claim 1 wherein monitoring the pressure within said cylinder comprises using a pressure transducer.

5. The method of claim 1 wherein adjusting said formation test procedure comprises:

determining if the pressure within said cylinder is less than the bubble point pressure of the formation fluid drawn into said cylinder;

maintaining the position of said drawdown piston until escaped formation fluid gas recombines into solution with the formation fluid; and

continuing drawing down said drawdown piston.

6. The method of claim 1 wherein adjusting said formation test procedure comprises:

determining if the pressure within said cylinder is less than the bubble point pressure of the formation fluid drawn into said cylinder;

resetting said drawdown piston;

performing said formation test procedure with a decreased draw down rate of said drawdown piston.

7. The method of claim 1 wherein adjusting said formation test procedure comprises:

determining if the pressure within said cylinder is less than the bubble point pressure of the formation fluid drawn into said cylinder;

resetting said drawdown piston;

performing said formation test procedure with a decreased amount of volume created by drawing down said drawdown piston.

8. The method of claim 1 wherein adjusting said formation test procedure comprises:

determining if the pressure within said cylinder is less than the bubble point pressure of the formation fluid drawn into said cylinder;

resetting said drawdown piston;

performing said formation test procedure comprising;

drawing down said drawdown piston to create a volume within said cylinder;

drawing formation fluid into the volume in said cylinder; and

monitoring the pressure within said cylinder;

monitoring the position of said drawdown piston during said formation test procedure;

determining the amount of volume created by drawing down said drawdown piston;

determining the bubble point of the formation fluid;

resetting said drawdown piston; and

performing said formation test procedure comprising maintaining the pressure within said cylinder above the bubble point pressure of the formation fluid while drawing down said drawdown piston.

9. The method of claim 8 wherein maintaining the pressure within said cylinder above the bubble point pressure of the formation fluid comprises decreasing the amount of volume created by said drawdown piston.

10. The method of claim 8 wherein maintaining the pressure within said cylinder above the bubble point pressure of the formation fluid comprises decreasing the draw down rate of said drawdown piston.

11. The method of claim 8 wherein maintaining the pressure within said cylinder above the bubble point pressure of the formation fluid comprises decreasing the amount of volume created by said drawdown piston and decreasing the draw down rate of said drawdown piston

12. The method of claim 8 wherein maintaining the pressure within said cylinder above the bubble point pressure of the formation fluid comprises variably controlling the amount of volume created by said drawdown piston while drawing down said drawdown piston.

13. The method of claim 8 wherein maintaining the pressure within said cylinder above the bubble point pressure of the formation fluid comprises variably controlling the draw down rate of said drawdown piston while drawing down said drawdown piston.

14. The method of claim 8 wherein maintaining the pressure within said cylinder above the bubble point pressure of the formation fluid comprises variably controlling the amount of volume created by said drawdown piston and the draw down rate of said drawdown piston while drawing down said drawdown piston.

15. The method of claim 1 wherein adjusting said formation test procedure comprises:

monitoring the position of said drawdown piston during said formation test procedure;

variably controlling the drawdown of said drawdown piston to maintain a substantially constant drawdown rate of said drawdown piston.

16. The method of claim 15 further comprising:

monitoring the position of said drawdown piston with a controller in said formation tester;

analyzing the position of said drawdown piston with said controller during the drawing down of said drawdown piston; and

controlling said formation test procedure with said controller.

17. The method of claim 1 wherein adjusting said formation test procedure comprises:

resetting said drawdown piston;

creating a pressure drop in said cylinder by isolating said cylinder from the formation fluid and drawing down said drawdown piston to create a volume within said cylinder;

allowing the formation fluid to communicate with the volume in said cylinder; and

drawing formation fluid into the volume in said cylinder.

18. The method of claim 17 wherein isolating said cylinder comprises controlling a flowline valve between said formation probe assembly and said cylinder with a controller.

19. The method of claim 1 wherein adjusting said formation test procedure comprises:

monitoring the pressure in the borehole;

transmitting the borehole and cylinder pressure data from downhole to the surface;

determining if the pressure in said cylinder is substantially equal to the pressure in the borehole;

transmitting formation test procedure commands from the surface to a controller in said formation tester;

aborting said formation test procedure using said controller to retract said formation probe assembly and reset said drawdown piston; and

re-performing said formation test procedure.

20. The method of claim 1 wherein adjusting said formation test procedure comprises:

monitoring the pressure in the borehole;

transmitting the borehole and cylinder pressure data to a controller in said formation tester;

analyzing said data with said controller to determine if the pressure in said cylinder is substantially equal to the pressure in the borehole;

aborting said formation test procedure by using said controller to retract said formation probe assembly and reset said drawdown piston; and

re-performing said formation test procedure.

21. The method of claim 1 wherein adjusting said formation test procedure comprises:

monitoring the pressure in the borehole;

transmitting the borehole and cylinder pressure data from downhole to the surface;

determining if the seal formed by said formation probe assembly is deteriorating;

transmitting formation test procedure commands from the surface to a controller in said formation tester; and

increasing the force of the formation probe assembly against the formation.

22. The method of claim 21 wherein increasing the force of the formation probe assembly against the formation comprises said controller increasing hydraulic pressure in a hydraulic flowline used to extend said formation probe assembly.

23. The method of claim 1 wherein adjusting said formation test procedure comprises:

monitoring the pressure in the borehole;

transmitting the borehole and cylinder pressure data to a controller in said formation tester;

analyzing said data with said controller to determine if the seal formed by said formation probe assembly is deteriorating; and

transmitting commands from said controller to increase the force of the formation probe assembly against the formation.

24. The method of claim 23 wherein increasing the force of the formation probe assembly against the formation comprises increasing the hydraulic pressure in a hydraulic flowline used to extend said formation probe assembly.

25. A method of testing a downhole formation comprising:

disposing a formation tester on a drill string in a borehole;

performing a formation test procedure with said formation tester comprising;

forming a seal between a formation probe assembly of said formation tester and the formation;

operating a hydraulic pump to create hydraulic pressure;

isolating a drawdown piston from the hydraulic pressure;

communicating the hydraulic pressure to said drawdown piston once a minimum hydraulic pressure is produced by said hydraulic pump;

drawing down said drawdown piston at a substantially constant drawdown rate with the hydraulic pressure;

creating a volume within a cylinder within said formation tester by drawing down said drawdown piston;

drawing formation fluid into the volume in said cylinder; and

monitoring the pressure within said cylinder.

26. The method of claim 25 further comprising isolating said drawdown piston from the hydraulic pressure with a sequencing valve.

27. A method of testing a downhole formation comprising:

disposing a formation tester on a drill string in a borehole;

performing a formation test procedure with said formation tester comprising;

forming a seal between a formation probe assembly of said formation tester and the formation;

operating a hydraulic pump to create hydraulic pressure;

controlling the amount of hydraulic pressure communicated to a drawdown piston to be less than the amount of hydraulic pressure produced by said hydraulic pump;

drawing down said drawdown piston at a substantially constant drawdown rate with the hydraulic pressure;

creating a volume within a cylinder within said formation tester by drawing down said drawdown piston;

drawing formation fluid into the volume in said cylinder; and

monitoring the pressure within said cylinder.

28. The method of claim 27 further comprising controlling the amount of hydraulic pressure communicated to said drawdown piston with a choke.