Drilling system and method for controlling equivalent circulating density during drilling of wellbores

• US 20030066650A1
• Filed: 07/09/2002
• Published: 04/10/2003
• Est. Priority Date: 07/15/1998
• Status: Active Grant

• Current Assignee: Baker Hughes Incorporated (Baker Hughes Company)
• Original Assignee: Baker Hughes Incorporated (Baker Hughes Company)
• Inventors: Aronstam, Peter, Watkins, Larry, Fontana, Peter
• Granted Patent: US 7,270,185 B2
• Time in Patent Office: Days
• US Class Current: 166/358
• CPC Class Codes: E21B 21/001 specially adapted for underwater drilling dual gradient drilling E21B21/082
• CPC Class Codes: E21B 21/085 Underbalanced techniques, i.e. where borehole fluid pressure is below formation pressure
• CPC Class Codes: E21B 33/076 specially adapted for underwater installations
• CPC Class Codes: E21B 43/12 Methods or apparatus for controlling the flow of the obtained fluid to or in wells E21B43/25 takes precedence; valve arrangements E21B34/00
• CPC Class Codes: E21B 47/001 for underwater installation
• CPC Class Codes: E21B 7/12 Underwater drilling using heave compensators E21B19/09

Abstract

A drilling system for drilling subsea wellbores includes a tubing-conveyed drill bit that passes through a subsea wellhead. Surface supplied drilling fluid flows through the tubing, discharges at the drill bit, returns to the wellhead through a wellbore annulus, and flows to the surface via a riser extending from the wellhead. A flow restriction device positioned in the riser restricts the flow of the returning fluid while an active fluid device controllably discharges fluid from a location below to just above the flow restriction device in the riser, thereby controlling bottomhole pressure and equivalent circulating density (“ECD”). Alternatively, the fluid is discharged into a separate return line thereby providing dual gradient drilling while controlling bottomhole pressure and ECD. A controller controls the energy and thus the speed of the pump in response to downhole measurement(s) to maintain the ECD at a predetermined value or within a predetermined range.

Claims

19. A method for supporting subsea wellbore operations, comprising:

(a) providing drilling fluid into a wellbore via a supply conduit;

(b) conveying the drilling fluid from the wellbore to a predetermined location via a return conduit including a riser, the supply conduit and return conduit forming a fluid circuit; and

(c) conveying the drilling fluid from a first selected location on the riser to a second selected location with an active pressure differential device (“

APD device”

).

20. The method according to claim 19 further comprising selectively diverting the drilling fluid from the riser to the APD device with a flow restriction device positioned in the return conduit.

21. The method according to claim 19 wherein the second selected location is one of (i) a section of the riser uphole of the first selected location;

and (ii) a separate line to a surface location.

22. The method according to claim 19 wherein the second selected location is a separate line to a surface location;

and a section of the riser uphole of the first selected location is at least partially filled with a fluid having a density different from that of the drilling fluid.

23. The method according to claim 19, further comprising positioning the APD device between 1000 ft. below the sea level and the sea bottom.

24. The method of claim 19, wherein the APD device is one of:

(i) at least one centrifugal pump;

(ii) a turbine;

(iii) a jet pump and (iv) a positive displacement pump.

25. The method of claim 19 further comprising controlling the APD device to control the equivalent circulating density in at least a portion of the fluid circuit.

26. The method of claim 25, wherein the APD device is controlled in response to pressure.

27. The method of claim 26, wherein the pressure is one of:

(i) bottomhole pressure;

(ii) measured at a location in the supply conduit;

(iii) measured at well control equipment associated with the wellbore;

(iv) measured in the return conduit;

(v) measured in a bottomhole assembly;

(vi) measured at the surface;

(vii) stored in a memory associated with the controller; and

(viii) measured near an inlet to the APD device.

28. The method of claim 19, further comprising controlling the APD device to provide a differential pressure to control a bottomhole pressure to one of:

(i) maintain the bottomhole pressure at a predetermined value;

(ii) maintain the bottomhole pressure within a range;

(iii) maintain the pressure in the wellbore at at-balance condition;

(iv) maintain the pressure in the wellbore at under-balance condition; and

(v) reduce the bottomhole pressure by a selected amount.

29. The method according to claim 19, wherein the controller controls the fluid flow device to maintain the equivalent circulating density at one of (i) a predetermined value, and (ii) within a predetermined range.

30. The method according to claim 19 further comprising drill string disposed in the wellbore;

and a drilling assembly connected to the drill string.

60. The method of claim 19, wherein controlling the APD Device includes one of:

(i) maintaining bottomhole pressure at a certain value;

(ii) maintaining bottomhole pressure within a range;

(iii) maintaining wellbore at at-balance condition; and

(iv) maintaining wellbore at underbalance condition.

31. A wellbore system for performing subsea downhole wellbore operations comprising:

(a) a tubing receiving fluid from a source adjacent an upper end of the tubing;

(b) a subsea wellhead assembly above a wellbore receiving the tubing, said wellhead assembly adapted to receive said fluid after it has passed down through said tubing and back up through an annulus between the tubing and the wellbore;

(c) a riser extending up from the wellhead assembly to the sea level for conveying returning fluid from the wellhead to the sea level, with the tubing, annulus, wellhead and the riser forming a subsea fluid circulation system;

(d) a flow restriction device adapted to restrict flow of the fluid returning to the sea level; and

(e) a fluid flow device for diverting returning fluid about the flow restriction device to control equivalent circulating density of fluid circulating in the fluid circulation system.

1. A system for supporting subsea wellbore operations, comprising:

(a) a supply conduit for providing drilling fluid into a wellbore;

(b) a return conduit including a riser for conveying the drilling fluid from the wellbore to a predetermined location, the supply conduit and return conduit forming a fluid circuit; and

(c) an active pressure differential device (“

APD device”

) adapted to selectively receive the drilling fluid from a first selected location on the riser and convey the drilling fluid to a second selected location.

2. The system according to claim 1 further comprising a flow restriction device positioned in the return conduit for selectively diverting the drilling fluid from the riser to the APD device.

3. The system according to claim 1 wherein the second selected location is one of (i) a section of the riser uphole of the first selected location;

and (ii) a separate line to a surface location.

4. The system according to claim 1 wherein the second selected location is a separate line to a surface location;

and a section of the riser uphole of the first selected location is at least partially filled with a fluid having a density different from that of the drilling fluid.

5. The system of claim 1, wherein the APD device is located at one of (i) in the riser, (ii) outside the riser, and (iii) in an annulus of the wellbore.

6. The system of claim 1, wherein the APD device is between 1000 ft. below the sea level and the sea bottom.

7. The system of claim 1, wherein the APD device is one of:

(i) at least one centrifugal pump;

(ii) a turbine;

(iii) jet pump; and

(iv) a positive displacement pump.

8. The system according to claim 1 wherein the APD device is configured to control equivalent circulating density of the drilling fluid in at least a portion of the fluid circuit.

9. The system of claim 1 further comprising a controller that controls the APD device to control the equivalent circulating density in at least a portion of the fluid circuit.

10. The system of claim 9, wherein the controller controls the APD device in response to pressure.

11. The system of claim 10, wherein the pressure is one of:

(i) bottomhole pressure;

(ii) measured at a location in the supply conduit;

(iii) measured at well control equipment associated with the wellbore;

(iv) measured in the return conduit;

(v) measured in a bottomhole assembly;

(vi) measured at the surface;

(vii) stored in a memory associated with the controller; and

(viii) measured near an inlet to the APD device.

12. The system of claim 9, wherein the controller controls the differential pressure to one of:

(i) maintain the bottomhole pressure at a predetermined value;

(ii) maintain the bottomhole pressure within a range;

(iii) maintain the pressure in the wellbore at at-balance condition;

(iv) maintain the pressure in the wellbore at under-balance condition; and

(v) reduce the bottomhole pressure by a selected amount.

13. The system of claim 9, wherein the controller controls the APD device to maintain the equivalent circulating density at one of (i) a predetermined value, and (ii) within a predetermined range.

14. The system of claim 9 further comprising at least one sensor providing pressure measurements of the drilling fluid in the fluid circuit.

15. The system of claim 14, wherein the controller controls the APD device in response to the pressure measurement and according to programmed instructions provided thereto.

16. The system of claim 1 further comprising drill string disposed in the wellbore;

and a drilling assembly connected to the drill string for forming the wellbore.

17. The system of claim 1 wherein a controller operably coupled to the APD device controls the APD device in response to a parameter of interest.

18. The system of claim 17, wherein the parameter of interest is one of:

(i) pressure;

(ii) flow rate;

(iii) characteristic of fluid in the wellbore; and

(iv) a formation characteristic.

32. The wellbore system of claim 31, wherein the active fluid flow device is located at one of (i) in the riser, (ii) outside the riser, and (iii) in the annulus.

33. The wellbore system of claim 31, wherein the active fluid flow device is one of:

(i) at least one centrifugal pump;

(ii) a turbine;

(iii) and (iv) a positive displacement pump.

34. The wellbore system of claim 31 further comprising a controller that controls the fluid flow device to control the equivalent circulating density.

35. The wellbore system of claim 34, wherein the controller controls the active flow fluid device in response to pressure, the pressure being one of:

(i) bottomhole pressure;

(ii) measured at a location in the drill string;

(iii) measured at the well control equipment;

(iv) measured in the riser;

(v) measured in a bottomhole assembly carrying the drill bit;

(vi) measured at the surface;

(vii) stored in a memory; and

(viii) measured near the inlet to the active fluid flow device.

36. The wellbore system of claim 34, wherein the controller controls the differential pressure to control the bottomhole pressure to one of:

(i) maintain the bottomhole pressure at a predetermined value;

(ii) maintain the bottomhole pressure within a range;

(iii) maintain the pressure in the wellbore at at-balance condition;

(iv) maintain the pressure in the wellbore at under-balance condition; and

(v) reduce the bottomhole pressure by a selected amount.

37. The wellbore system of claim 34, wherein the controller controls the fluid flow device to maintain the equivalent circulating density at one of (i) a predetermined value, and (ii) within a predetermined range.

38. The wellbore system of claim 34, wherein the controller controls the fluid flow device in response to pressure measurement provided by a sensor positioned in the drilling fluid and according to programmed instructions provided thereto.

40. The wellbore system of claim 31 further comprising a drilling assembly connected to the tubing for forming a wellbore.

59. The method of claim 14 further comprising providing at least one pressure sensor to provide signals indicative of pressure in the wellbore, the at least one pressure sensor location being selected from a group consisting of:

(i) the annulus of the wellbore;

(ii) a location in the drill string;

(iii) well control equipment;

(iv) the riser;

(v) a bottomhole assembly carrying the drill bit;

(vi) the surface;

(vii) a memory; and

(viii) near the inlet of the APD device.

38-1. The wellbore system of claim 31, wherein the active fluid flow device returns the returning fluid to the surface via the riser.

41. A method for drilling a subsea wellbore wherein a riser extends from a well control equipment at the sea bed to the surface, comprising:

(a) providing a drill string having a drill bit at a bottom end thereof extending from the surface into the wellbore through the riser;

b) supplying drilling fluid to the drill string, said drilling fluid discharging at the bottom of the drill bit and returning to the surface via an annulus between the drill string and the riser, the annulus defining a portion of the return fluid path;

(c) restricting the return fluid path in the riser at a preselected depth; and

(d) diverting returning fluid about the restriction to control equivalent circulating density of fluid at least downhole of the restriction.

42. The method of claim 41, wherein pumping is performed by an active fluid flow device.

43. The method of claim 41 further comprising returning the return fluid to the surface via a portion of the riser above the restriction.

44. The method of claim 41 further comprising controlling the diverting of the fluid with an active fluid flow device to create a selected pressure differential across the active fluid flow device.

45. The method of claim 44 further comprising providing at least one pressure sensor to provide signals indicative of pressure in the wellbore.

46. The method of claim 45 further comprising locating the at least one pressure sensor at one of:

(i) the annulus of the wellbore;

(ii) a location in the drill string;

(iii) well control equipment;

(iv) the riser;

(v) a bottomhole assembly carrying the drill bit;

(vi) the surface;

(vii) a memory; and

(viii) near the inlet of the active fluid flow device.

47. The method of claim 41, further comprising controlling the active fluid flow device to one of:

(i) maintain bottomhole pressure at a certain value;

(ii) maintain bottomhole pressure within a range;

(iii) maintain wellbore at at-balance condition; and

(iv) maintain wellbore at underbalance condition.

48. A dual gradient drilling system for drilling a subsea wellbore, the system having a riser extending from a well control equipment at the sea bed over the wellbore to the surface, comprising:

(a) a drill string having a drill bit at a bottom end thereof extending from the surface into the wellbore through the riser and the well control equipment for drilling the wellbore;

(b) a source of drilling fluid supplying drilling fluid into the drill string, said drilling fluid discharging at the bottom of the drill bit and returning to the surface in part via an annulus between the drill string and the riser, said annulus defining the return fluid path;

(c) a restriction device at a predetermined depth in the riser restricting the flow of the returning fluid through the riser uphole of the restriction device;

(d) an active pressure differential device (“

APD Device”

) on the riser pumping fluid from a location downhole of the restriction device to the surface by bypassing the riser section uphole of the restriction device; and

(e) a fluid with density less than that of the returning fluid (“

lower density fluid”

) in the riser uphole of the restriction device.

49. The system of claim 48, wherein the APD Device is one of:

(i) at least one centrifugal pump;

(ii) a turbine;

(iii) and (iv) a positive displacement pump.

50. The system of claim 48 further comprising a separate return line outside the riser extending from the APD Device to the surface to carry the returning fluid to the surface by bypassing the riser.

51. The system of claim 48 further comprising a controller for controlling the APD Device to create a pressure differential across the APD Device to reduce a selected pressure associated with the drilling fluid.

52. The system of claim 48, further comprising a controller associated with the APD device to control the differential pressure to one of:

(i) maintain the bottomhole pressure at a predetermined value;

(ii) maintain the bottomhole pressure within a range;

(iii) maintain the pressure in the wellbore at at-balance condition;

(iv) maintain the pressure in the wellbore at under-balance condition; and

(v) reduce the bottomhole pressure by a selected amount.

53. The system of claim 48, further comprising a controller for controlling the APD Device in response to one of:

(i) a parameter of interest;

(ii) programmed instruction stored for use by the controller; and

(iii) signals transmitted to the controller from a remote device.

54. A dual gradient drilling method for drilling a subsea wellbore wherein a riser extends from a well control equipment at the sea bed to the surface, comprising:

(a) providing a drill string having a drill bit at a bottom end thereof extending from the surface into the wellbore through the riser;

b) supplying drilling fluid to the drill string, said drilling fluid discharging at the bottom of the drill bit and returning to the surface in part via an annulus between the drill string and the riser, said annulus defining a portion of the return fluid path;

(c) restricting the return fluid path in the riser at a preselected depth;

(d) pumping fluid from the riser at a location downhole of the restriction to the surface by bypassing the riser uphole of the restriction; and

(e) filling the riser uphole of the restriction with a lighter fluid than the returning fluid to provide a fluid pressure gradient to the wellbore that is less than the pressure gradient formed by the fluid downhole of the restriction.

55. The method of claim 54, wherein pumping the fluid includes pumping with an active pressure differential device (“

APD Device”

).

56. The method of claim 55, wherein the APD Device is one of:

(i) at least one centrifugal pump;

(ii) a turbine;

(iii) and (iv) a positive displacement pump.

57. The method of claim 54 further comprising providing a separate return line outside the riser and extending to the surface to carry the returning fluid to the surface while bypassing the riser.

58. The method of claim 54 further comprising controlling the APD Device to create a selected pressure differential across the APD Device.