Method and system for controlling well fluid circulation rate

• US 6,755,261 B2
• Filed: 03/07/2002
• Issued: 06/29/2004
• Est. Priority Date: 03/07/2002
• Status: Expired due to Fees

• Current Assignee: Varco I/P Incorporated (NOV, Inc.)
• Original Assignee: Varco I/P Incorporated (NOV, Inc.)
• Inventors: Koederitz, William L.
• Primary Examiner(s): Bagnell, David
• Assistant Examiner(s): Smith, Matthew J
• Application Number:
  US10/113,631
• Publication Number:
  US 20030168258A1
• Time in Patent Office: 845 Days
• Field of Search: 175/25, 175/38, 175/48, 175/24, 175/40
• US Class Current: 175/25
• CPC Class Codes: E21B 21/08 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

Abstract

Methods and systems are provided for varying fluid pressure in a circulation system while circulating a kick out of a well bore 30 drilled through a subterranean formation using a drilling rig 25 and a drill string 50. The kick may be automatically circulated out of the well bore and/or a kill fluid may be circulated into the well bore. A controller 100 reduces the circulation rate by automatically controlling the rate of the pump 90 and the position of well bore choke 70. Various sensors interconnected with the controller may be used to maintain circulation system operation. The controller may control various components utilized in the circulation procedure to maintain a substantially constant bottom hole pressure on the formation while circulating the kick out of the well.

Claims

1. A method of varying fluid pressure in a circulation system while circulating a kick out of a well, the circulation system including a well bore drilled through a subterranean formation using a drilling rig, a drill string having a through bore and positioned at least partially within the well bore, a fluid pump for pumping a fluid through the drill string and into the well bore, and a drilling fluid choke in fluid communication with an annulus of the well bore, the method comprising:

pumping the fluid through the drill string, then through the well bore annulus and substantially back to the drilling rig, the fluid being pumped at a desired high fluid circulation rate;

monitoring a plurality of sensors for monitoring conditions of the circulation system while pumping the fluid; and

automatically reducing the fluid circulation rate to a predetermined reduced circulation rate in response to the monitored conditions, and the predetermined reduced circulation rate is the lowest reduced circulation rate for any of the monitored conditions.

2. The method as defined in claim 1, wherein a flow rate from the fluid pump and the position of the drilling fluid choke are automatically controlled when reducing the fluid circulation rate.

3. The method as defined in claim 2, wherein the position of the choke is adjusted to hold the pressure constant, then the measured pressure is compared with existing pressure data at that choke position and pump rate.

4. The method as defined in claim 1, further comprising:

detecting possible problems in the circulation system while maintaining fluid circulation at the predetermined reduced circulation rate.

5. The method as defined in claim 1, further comprising:

after reducing the fluid circulation rate to the predetermined reduced circulation rate, increasing fluid circulation rate to the desired high fluid circulation rate in response to the monitored conditions.

6. The method as defined in claim 1, wherein the monitored conditions include two or more of an alarm condition, fluid circulation rate change, lost circulation, plugging of the bit nozzles, mud-gas separation system operation, sensor failure, choke control operation, and fluid temperature or pressure conditions in the circulation system.

7. The method as defined in claim 1, wherein various fluid circulation rates and the fluid pump rate and choke position at various circulation rates are automatically compared to the monitored conditions.

8. The method as defined in claim 1, wherein the predetermined reduced circulation rate is a function of the number of unacceptable monitored conditions.

9. A method of varying fluid pressure in a circulation system while circulating a kick out of a well, the circulation system including a well bore drilled through a subterranean formation using a drilling rig, a drill string having a through bore and positioned at least partially within the well bore, a fluid pump for pumping a fluid through the drill string and into the well bore, and a drilling fluid choke in fluid communication with an annulus of the well bore, the method comprising:

pumping the fluid through the drill string, then through the well bore annulus and substantially back to the drilling rig, the fluid being pumped at a desired high fluid circulation rate;

monitoring a plurality of sensors for monitoring conditions of the circulation system while pumping the fluid;

automatically comparing monitored conditions to various fluid circulation rates and the fluid pump rate and choke position at various circulation rates;

automatically controlling a flow rate of fluid from the pump and the position of the drilling choke to reduce the fluid circulation rate to a predetermined reduced circulation rate in response to the monitored conditions; and

wherein the predetermined reduced circulation rate is a function of the number of unacceptable monitored conditions, and is the lowest reduced circulation rate for any of the monitored conditions.

10. The method as defined in claim 9, wherein the position of the choke is adjusted to hold the pressure constant, then the measured pressure is compared with existing pressure data at that choke position and pump rate.

11. The method as defined in claim 9 wherein the monitored conditions include two or more of an alarm condition, fluid circulation rate change, lost circulation, plugging of the bit nozzles, mud-gas separation system operation, sensor failure, choke control operation, and fluid temperature or pressure conditions in the circulation system.

12. The method as defined in claim 9, further comprising:

after reducing the fluid circulation rate to the predetermined reduced circulation rate, increasing fluid circulation rate to the desired high fluid circulation rate in response to the monitored conditions.

13. The method as defined in claim 9, further comprising:

detecting possible problems in the circulation system while maintaining fluid circulation at the predetermined reduced circulation rate.