Pressure control in drilling operations with choke position determined by Cv curve

Patent metadata

Field	Value
Publication number	US-10047578-B2
Application number	US-201214412631-A
Country	US
Kind code	B2
Filing date	Jul 2, 2012
Priority date	Jul 2, 2012
Publication date	Aug 14, 2018
Grant date	Aug 14, 2018

Abstract

A method of controlling pressure in a wellbore can include determining a desired position for a choke, the determining being based on a Cv curve for the choke, and adjusting the choke to the desired position, thereby producing a desired backpressure. A wellbore drilling system can include a choke which variably restricts flow of fluid from the wellbore, and a control system which compares actual and desired wellbore pressures and, in response to a difference between the actual and desired wellbore pressures, adjusts the choke to a predetermined position which corresponds to a desired Cv of the choke. A method of controlling pressure in a wellbore can include comparing an actual wellbore pressure to a desired wellbore pressure and, in response to a difference between the actual and desired wellbore pressures, adjusting a choke to a predetermined position, the predetermined position corresponding to a desired Cv of the choke.

First claim

What is claimed is:

1. A method of controlling pressure in a wellbore, the method comprising:
determining a desired position for a choke, the determining being based on a Cv curve for the choke;
adjusting the choke to the desired position, thereby producing a desired backpressure in the wellbore; and
calibrating a second Cv curve of the choke based on changes to a fluid condition through the choke, changes to the choke, or any combination thereof.

2. The method of claim 1 , wherein the Cv curve relates a Cv of the choke to a choke position.

3. The method of claim 1 , wherein the determining is performed in response to there being a difference between an actual wellbore pressure and a desired wellbore pressure.

4. The method of claim 1 , wherein the adjusting is performed automatically in response to there being a predetermined level of difference between an actual wellbore pressure and a desired wellbore pressure.

5. The method of claim 1 , further comprising calibrating the Cv curve.

6. The method of claim 5 , wherein the calibrating is performed during a drilling operation.

7. The method of claim 5 , wherein the calibrating is performed with sensor measurements of flow rate and pressure.

8. The method of claim 5 , wherein the calibrating is performed periodically.

9. The method of claim 1 , wherein the determining further comprises determining the desired backpressure, calculating a desired Cv corresponding to the desired backpressure, and determining the desired position which corresponds to the desired Cv.

10. The method of claim 1 , wherein adjusting the choke further comprises transmitting to a programmable logic controller an indication of the desired position of the choke.

11. A system for drilling a wellbore, the system comprising:
a choke which variably restricts flow of fluid from the wellbore; and
a control system which compares an actual wellbore pressure to a desired wellbore pressure and, in response to a difference between the actual and desired wellbore pressures, adjusts the choke to a predetermined position which corresponds to a desired Cv of the choke, wherein the predetermined position is related to the desired Cv by a Cv curve for the choke, and the control system calibrates the Cv curve and a second Cv curve based on changing conditions within the wellbore.

12. The well drilling system of claim 11 , wherein the Cv curve is calibrated during a drilling operation.

13. The well drilling system of claim 11 , wherein the Cv curve is calibrated with sensor measurements of flow rate and pressure.

14. The well drilling system of claim 11 , wherein the Cv curve is calibrated periodically.

15. The well drilling system of claim 11 , wherein an indication of the predetermined position of the choke is transmitted to a programmable logic controller of the control system.

16. The well drilling system of claim 11 , wherein the control system automatically adjusts the choke in response to there being a predetermined level of the difference between the actual wellbore pressure and the desired wellbore pressure.

17. The well drilling system of claim 11 , wherein the predetermined position of the choke produces a desired backpressure in a line connected to the wellbore.

18. A method of controlling pressure in a wellbore, the method comprising:
comparing an actual wellbore pressure to a desired wellbore pressure; and
in response to a difference between the actual and desired wellbore pressures, adjusting a choke to a predetermined position, the predetermined position corresponding to a desired Cv of the choke, wherein the predetermined position is related to the desired Cv of the choke by a Cv curve
calibrating a second Cv curve of the choke based on changes to a fluid flow through the choke.

19. The method of claim 18 , wherein the adjusting is performed automatically in response to there being a predetermined level of the difference between the actual wellbore pressure and the desired wellbore pressure.

20. The method of claim 18 , wherein the calibrating is performed during a drilling operation.

21. The method of claim 18 , wherein the calibrating is performed with sensor measurements of flow rate and pressure.

22. The method of claim 18 , wherein the calibrating is performed periodically.

23. The method of claim 18 , further comprising determining a desired backpressure to be applied to the wellbore, calculating the desired Cv corresponding to the desired backpressure, and determining a choke position which corresponds to the desired Cv.

24. The method of claim 18 , wherein adjusting the choke further comprises transmitting to a programmable logic controller an indication of the predetermined position of the choke.

25. The method of claim 18 , wherein adjusting the choke produces a desired backpressure in a line connected to the wellbore.

Assignees

• Lovorn James R
• Davis Nancy S
• Butler Cody N
• Halliburton Energy Services Inc

Inventors

• Lovorn James R
• Davis Nancy S
• Butler Cody N

Classifications

• E21B21/10

  Valve arrangements in drilling-fluid circulation systems · CPC title

• E21B47/06

  Measuring temperature or pressure · CPC title

• E21B34/025

  Chokes or valves in wellheads and sub-sea wellheads for variably regulating fluid flow · CPC title

• E21B21/08 Primary

  Controlling or monitoring pressure or flow of drilling fluid, e.g. automatic filling of boreholes, automatic control of bottom pressure (valve arrangements therefor E21B21/10) · CPC title

• E21B34/02

  in well heads · CPC title