SYSTEM AND METHOD FOR SAFE WELL CONTROL OPERATIONS

• US 20110214882A1
• Filed: 03/04/2011
• Published: 09/08/2011
• Est. Priority Date: 03/05/2010
• Status: Active Grant

• Current Assignee: Safekick Americas LLC
• Original Assignee: Safekick Americas LLC
• Inventors: SANTOS, HELIO
• Granted Patent: US 8,528,660 B2
• Time in Patent Office: Days
• US Class Current: 166/373
• 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
• CPC Class Codes: E21B 21/10 Valve arrangements in drilling-fluid circulation systems
• CPC Class Codes: E21B 44/00 Automatic control systems specially adapted for drilling operations, i.e. self-operating systems which function to carry out or modify a drilling operation without intervention of a human operator, e.g. computer-controlled drilling systems; Systems specially adapted for monitoring a plurality of drilling variables or conditions

Abstract

A system and method for safely controlling a well being drilled or that has been drilled into a subterranean formation in which a conventional blow-out preventer operates to close the well bore to atmosphere upon the detection of a fluid influx event. Fluid pressures as well as fluid flow rates into and out of the well bore are measured and monitored to more accurately and confidently determine the fracture pressure and pore pressure of the formation and perform well control operations in response to a fluid influx event. During a suspected fluid influx event, one or more of the fluid flow and pressure measurements are used to confirm the fluid influx event and to safely regain well control by circulating the fluid influx out of the well through a choke line while maintaining the pressure inside the well between specified, selected limits, such as between the fracture and pore pressures.

Claims

1. A system (10) for controlling a well being drilled into a subterranean formation (14), said system comprising,

a tubular drill string (20) having a lower end (22) extending into a borehole 2 and an upper end (24), said tubular drill string having a drill bit (26) at its lower end,

a drill string turning device (38) arranged and designed to turn said drill bit in said borehole in which a borehole annulus (18) is defined between an outer diameter of said tubular drill string and an inner diameter of said borehole,

a blow-out preventer (32) arranged and designed to close said borehole from atmosphere only at a time when said drill bit is stationary,

a fluid pump (40) in fluid communication with a surface fluid reservoir (42),

a choke line (56) coupled between said borehole annulus and said surface fluid reservoir and arranged and designed to permit fluid communication therebetween when said blow-out preventer closes said borehole from atmosphere,

a fluid injection line (48) extending between said fluid pump and said upper end of said drill string, said fluid injection line capable of providing fluid communication therebetween,

said fluid injection line, said drill string, said borehole annulus and said choke line defining a fluid pathway when said blow-out preventer closes said borehole from atmosphere,

an outlet flow rate measurement device (50) disposed in said choke line, said outlet flow rate measurement device arranged and designed to measure flow rate through said choke line and to generate a signal F_out(t) representative of actual choke line flow rate as a function of time (t),

an outlet pressure measurement device (64) disposed in said choke line, said outlet pressure measurement device arranged and designed to measure choke line pressure and to generate a signal P_out(t) representative of actual choke line pressure as a function of time (t),

a central control unit (80) arranged and designed, while said borehole is closed from atmosphere by said blow-out preventer,

to receive said signals F_out(t) and P_out(t),

to determine a formation fracture pressure as a function of said signals F_out(t) and P_out(t),

to determine a formation pore pressure as a function of said signals F_out(t) and P_out(t),

to generate a signal P_ann(t) representative of pressure at a desired well bore depth as a function of time (t),

to generate a signal FC(t) representative of choke line flow rate required as a function of time (t) to maintain said signal P_ann(t) below said formation fracture pressure and above said formation pore pressure, and

to transmit said signal FC(t), and

a flow control device (70) disposed in said choke line, said flow control device arranged and designed to control fluid flow therethrough in response to said signal FC(t) transmitted and received from said central control unit, thereby controlling choke line flow ate to maintain said signal P_ann(t) below said formation fracture pressure and above said formation pore pressure.

2. The system of claim 1 further comprising,

an inlet flow rate measurement device (52) disposed in said fluid injection line, said inlet flow rate measurement device arranged and designed to measure fluid flow rate through said fluid injection line and to generate a signal F_in(t) representative of actual fluid injection line flow rate as a function of time (t).

3. The system of claim 2 wherein,

said central control unit is further arranged and designed to receive said signal F_in(t) and to determine said formation pore pressure as a function of said signals F_out(t) and P_out(t) when said flow control device controls fluid flowrate through said choke line such that said signal F_in(t) first becomes consistently less than said signal F_out(t).

4. The system of claim 2 wherein,

said central control unit is further arranged and designed to receive said signal F_in(t) and to determine said formation fracture pressure as a function of said signals F_out(t) and P_out(t) when said flow control device controls fluid flow rate through said choke line such that said signal F_in(t) first becomes consistently greater than said signal F_out(t).

5. The system of claim 1 further comprising,

an inlet pressure measurement device (62) disposed in said fluid injection line, said inlet pressure measurement device arranged and designed to measure fluid injection line pressure and to generate a signal P_in(t) representative of actual fluid injection line pressure as a function of time (t), and wherein,

said central control unit is further arranged and designed to receive said signal P_in(t).

6. The system of claim 1 wherein,

said central control unit is further arranged and designed to calculate an increase in fluid weight to be pumped through said fluid pathway based upon said formation pore pressure.

7. The system of claim 1 further comprising,

a kill line (54) coupled between said fluid pump and said borehole annulus and capable of providing fluid communication therebetween, and wherein,

said kill line, said borehole annulus, and said choke line define said fluid pathway when said blow-out preventer closes said borehole from atmosphere.

8. The system of claim 7 further comprising,

an inlet flow rate measurement device (60) disposed in said kill line, said inlet flow rate measurement device arranged and designed to measure fluid flow rate through said kill line and to generate a signal F_in2(t) representative of actual kill line flow rate as a function of time (t).

9. The system of claim 8 wherein,

said central control unit is further arranged and designed to receive said signal F_in2(t) and to determine said formation pore pressure as a function of said signals F_out(t) and P_out(t) when said flow control device controls fluid flow rate through said choke line such that said signal F_in2(t) first becomes consistently less than said signal F_out(t).

10. The system of claim 8 wherein,

said central control unit is further arranged and designed to receive said signal F_in2(t) and to determine said formation fracture pressure as a function of said signals F_out(t) and P_out(t) when said flow control device controls fluid flow rate through said choke line such that said signal F_in2(t) first becomes consistently greater than said signal F_out(t).

11. The system of claim 7 further comprising,

an inlet pressure measurement device (62) disposed in said kill line, said inlet pressure measurement device arranged and designed to measure kill line pressure and to generate a signal P_in2(t) representative of actual kill line pressure as a function of time (t), and wherein,

said central control unit is further arranged and designed to receive said signal P_in2(t).

12. The system of claim 7 wherein,

said central control unit is further arranged and designed to calculate an increase in fluid weight to be pumped through said fluid pathway based upon said formation pore pressure.

13. The system of claim 1 further comprising,

a communication link (97) between said central control unit and a remote unit (91, 93, 95, 99) to transmit rig data from said central control unit to said remote unit for observation of said rig data by well control experts.

14. The system of claim 1 wherein,

said central control unit is further arranged and designed to simulate a well control event whereby rig personnel respond to said well control event by implementing well control procedures using said system.

15. The system of claim 1 wherein,

said signal FC(t) is representative of choke line pressure required as a function of time (t) to maintain said signal P_ann(t) below said formation fracture pressure and above said formation pore pressure and

said flow control device controls choke line pressure to maintain said signal P_ann(t) below said formation fracture pressure and above said formation pore pressure

16. A well control system comprising,

a blow-out preventer (32) arranged and designed to close a well bore annulus (18) from atmosphere only at a time when drilling is ceased,

a choke line (56) coupled between said well bore annulus and a surface fluid reservoir (42),

an outlet flow rate measurement device (50) disposed in said choke line, said outlet flow rate measurement device arranged and designed to measure flow rate through said choke line and to generate a signal F_out(t) representative of actual choke line flow rate as a function of time (t),

a central control unit arranged and designed, while said blow-out preventer closes said well bore annulus from atmosphere,

to receive said signal F_out(t),

to generate a signal P_ann(t) representative of pressure at a desired well bore depth as a function of time (t) and

to generate and transmit a signal FC(t) representative of choke line pressure required as a function of time (t) to drive said signal P_ann(t) toward a desired value, and

a flow control device (70) disposed in said choke line, said flow control device responsive to said signal FC(t) and arranged and designed to control fluid flow therethrough, thereby controlling choke line pressure to drive said signal P_ann(t) toward said desired value.

17. The well control system of claim 16 further comprising,

an inlet flow rate measurement device (52) disposed in an inlet line (48, 54) coupled between a fluid pump (40) and said well bore annulus, said inlet flow rate measurement device arranged and designed to measure fluid flow rate through said inlet line and to generate a signal F_in(t) representative of actual inlet line flow rate as a function of time (t) and

an outlet pressure measurement device (64) disposed in said choke line, said outlet pressure measurement device arranged and designed to measure choke line pressure and to generate a signal P_out(t) representative of actual choke line pressure as a function of time (t).

18. The well control system of claim 17 wherein,

said central control unit is further arranged and designed to receive said signal F_in(t) and to determine a formation pore pressure as a function of said signals F_out(t) and P_out(t) when said flow control device controls fluid flow rate through said choke line such that said signal F_in(t) first becomes consistently less than said signal F_out(t).

19. The well control system of claim 18 wherein,

said central control unit is further arranged and designed to determine a formation fracture pressure as a function of said signals F_out(t) and P_out(t) when said flow control device controls fluid flow rate through said choke line such that said signal F_in(t) first becomes consistently greater than said signal F_out(t).

20. The well control system of claim 19 wherein,

said desired value of said signal P_ann(t) is between said formation pore pressure and said formation fracture pressure.

21. The well control system of claim 16 further comprising,

a communication link (97) between said central control unit and a remote unit (91, 93, 95, 99) to transmit rig data from said central control unit to said remote unit for observation of said rig data by well control experts.

22. The well control system of claim 16 wherein,

said central control unit is further arranged and designed to simulate a well control event whereby personnel respond to said well control event by implementing well control procedures using said system.

23. The well control system of claim 16 wherein,

said signal FC(t) is representative of choke line flow rate required as a function of time (t) to drive said signal P_ann(t) toward said desired value and

said flow control device controls choke line flow rate to drive said signal P_ann(t) toward said desired value.

24. A method for controlling a well being drilled into a subterranean formation 14, said method comprising the steps of,

turning a tubular drill string (20) that extends into a borehole (12), said tubular drill string having an upper end (24) and a lower end (22) and a drill bit (26) disposed at said lower end,

stopping said turning of said tubular drill string when a fluid influx is detected entering said borehole,

closing a blow-out preventer (32), said blow-out preventer arranged and designed to close said borehole from atmosphere only at a time when said drill bit is stationary,

operating a fluid pump (40) to pump a fluid from a surface fluid reservoir (42) through a fluid injection line (48), into and through said tubular drill string, out said drill bit and into a borehole annulus (18), said borehole annulus created between an outer diameter of said tubular drill string and an inner diameter of said borehole by said turning of said drill string and said drill bit in said borehole,

operating a flow control device (70) disposed in a choke line (56), said choke line coupled between said borehole annulus and said surface fluid reservoir and arranged and designed to permit fluid communication therebetween in cooperation with said flow control device while said blow-out preventer closes said borehole from atmosphere, said fluid injection line, said tubular drill string, said borehole annulus, and said choke line defining a fluid flow path through said borehole,

measuring actual outlet flow rate of fluid flowing through said choke line while said borehole is closed from atmosphere using an outlet flow measurement device (50) disposed in said choke line and arranged and designed to generate a signal F_out(t) representative of actual choke line fluid flow rate as a function of time (t),

measuring actual outlet pressure in said choke line while said borehole is closed from atmosphere using an outlet pressure measurement device (64) disposed in said choke line and arranged and designed to generate a signal P_out(t) representative of actual choke line pressure as a function of time (t),

transmitting said actual outlet flow rate signal F_out(t) and said actual outlet pressure signal P_out(t) to a central control unit (80), said central control unit arranged and designed to receive said signals, to determine a formation fracture pressure, to determine a formation pore pressure, to generate a signal P_ann(t) representative of pressure at a well bore depth as a function of time (t), and to generate a signal FC(t) representative of choke line flow rate required as a function of time (t) to maintain said signal P_ann(t) below said formation fracture pressure and above said formation pore pressure,

receiving said signal F_out(t) and said signal P_out(t) in said central control unit,

using said central control unit to determine said formation fracture pressure as a function of said signals F_out(t) and P_out(t),

using said central control unit to determine said formation pore pressure as a function of said signals F_out(t) and P_out(t),

using said central control unit to generate said signal P_ann(t).

using said central control unit to generate said signal FC(t),

transmitting said signal FC(t) to said flow control device, said flow control device arranged and designed to receive said signal FC(t),

receiving said signal FC(t) in said flow control device, said flow control device further arranged and designed to control fluid flow through said choke line in response to said signal FC(t), and

adjusting said flow control device in response to said signal FC(t) to control choke line fluid flow rate to maintain said signal P_ann(t) below said formation fracture pressure and above said formation pore pressure.

25. The method of claim 24 further comprising the steps of,

measuring actual inlet flow rate of fluid flowing through said fluid injection line using an inlet flow measurement device (52) arranged and designed to generate a signal F_in(t) representative of actual fluid injection line fluid flow rate as a function of time (t), and

transmitting said actual inlet flow rate signal F_in(t) to said central control unit, said central control unit arranged and designed to receive said signal F_in(t).

26. The method of claim 25 wherein,

said central control unit is further arranged and designed to receive said signal F_in(t) and to determine said formation pore pressure as a function of said signals F_out(t) and P_out(t) when said flow control device controls fluid flow rate through said choke line such that said signal F_in(t) first becomes consistently less than said signal F_out(t), and

said method further comprises the step of,

determining said formation pore pressure as a function of said signals F_out(t) and P_out(t).

27. The method of claim 26 wherein,

said central control unit is further arranged and designed to calculate an increase in fluid weight to be circulated through said fluid flow path based upon said formation pore pressure.

28. The method of claim 25 wherein,

said central control unit is further arranged and designed to receive said signal F_in(t) and to determine said formation fracture pressure as a function of said signals F_out(t) and P_out(t) when said flow control device controls fluid flow rate through said choke line such that said signal F_in(t) first becomes consistently greater than said F_out(t), and

said method further comprises the step of,

determining said formation fracture pressure as a function of said signals F_out(t) and P_out(t).

29. The method of claim 24 further comprising the steps of,

measuring actual inlet pressure in said fluid injection line using an inlet pressure measurement device (62) arranged and designed to generate a signal P_in(t) representative of actual fluid injection line pressure as a function of time (t), and

transmitting said actual inlet pressure signal P_in(t) to said central control unit, said central control unit arranged and designed to receive said signal P_in(t).

30. The method of claim 24 further comprising the steps of,

establishing a communication link (97) between said central control unit and a remote unit (91, 93, 95, 99) and

transmitting rig data from said central control unit to said remote unit via said communication link for observation of said rig data by well control experts.

31. The method of claim 24 further comprising the steps of,

simulating a well control event and

training rig personnel to respond to said well control event by performing one or more steps of said method.

32. The method of claim 24 wherein,

said signal FC(t) is representative of choke line pressure required as a function of time (t) to maintain said signal P_ann(t) below said formation fracture pressure and above said formation pore pressure,

said flow control device is arranged and designed to control choke line pressure in response to said signal FC(t), and

said signal FC(t) controls choke line pressure to maintain said signal P_ann(t) below said formation fracture pressure and above said formation pore pressure.

33. In a well control system comprising,

a blow-out preventer (32) arranged and designed to close a well bore annulus (18) of a well 12 from atmosphere only at a time when drilling is ceased,

a choke line (56) coupled between said well bore annulus and a surface fluid reservoir (42),

an outlet flow rate measurement device (50) disposed in said choke line, said outlet flow rate measurement device arranged and designed to measure flow rate through said choke line and to generate a signal F_out(t) representative of actual choke line flow rate as a function of time (t),

an outlet pressure measurement device (64) disposed in said choke line, said outlet pressure measurement device arranged and designed to measure choke line pressure and to generate a signal P_out(t) representative of actual choke line pressure as a function of time (t),

a fluid pump (40) in fluid communication with said surface fluid reservoir (42),

an inlet flow rate measurement device (52) disposed in an inlet line (48, 50) coupled between said fluid pump (40) and said well bore annulus, said inlet flow rate measurement device arranged and designed to measure fluid flow rate through said inlet line and to generate a signal F_in(t) representative of actual inlet line flow rate as a function of time (t), and

a flow control device (70) disposed in said choke line and arranged and designed to control fluid flow rate through said choke line,

a well control method comprising the steps of,

closing said blow-out preventer in response to a fluid influx event,

permitting pressure in said well to stabilize while ceasing fluid circulation via said fluid pump and controlling said flow control device to permit no fluid flow therethrough,

operating said fluid pump to circulate fluid through said inlet line, said well bore annulus and said choke line,

ascertaining a hydrostatic condition of said well by monitoring at least said signal F_out(t) while controlling said flow control device to permit incremental increases in fluid flow rate therethrough,

permitting said well to achieve steady state after each incremental increase, and

confirming said fluid influx event when said signal F_out(t) remains greater than said signal F_in(t) after steady state is achieved following an incremental increase in fluid flow rate.

34. The well control method of claim 33 further comprising the step of,

determining formation pore pressure as a function of said signals F_out(t) and P_out(t) when said flow control device controls fluid flow rate through said choke line such that said signal F_in(t) first becomes consistently less than said signal F_out(t).

35. The well control method of claim 34 further comprising the step of,

calculating an increase in fluid weight of fluid to be circulated through said inlet line, said well bore annulus and said choke line based upon said formation pore pressure.

36. The well control method of claim 35 further comprising the step of,

operating said fluid pump to circulate fluid having said calculated increase in fluid weight through said inlet line, said well bore annulus, and said choke line.

37. The well control method of claim 33 further comprising the steps of,

establishing a communication link (97) between at least one of said measurement devices and a remote unit (91, 93, 95, 99),

transmitting at least one of said signals F_out(t), P_out(t), and F_in(t) to said remote unit via said communication link for observation of at least one of said signals F_out(t), P_out(t), and F_in(t) by well control experts, and

transmitting a control signal from said remote unit to said flow control device via said communication link to control fluid flow rate through said choke line.

38. The well control method of claim 33 wherein,

said fluid influx event is a simulated fluid influx event and

said steps of said well control method are conducted to train rig personnel in proper well control procedures.

39. In a well control system comprising,

a blow-out preventer (32) arranged and designed to close a well bore annulus (18) of a well 12 from atmosphere only at a time when drilling is ceased,

a choke line (56) coupled between said well bore annulus and a surface fluid reservoir (42),

an outlet flow rate measurement device (50) disposed in said choke line, said outlet flow rate measurement device arranged and designed to measure flow rate through said choke line and to generate a signal F_out(t) representative of actual choke line flow rate as a function of time (t),

a fluid pump (40) in fluid communication with said surface fluid reservoir (42), and

a flow control device (70) disposed in said choke line and arranged and designed to control fluid flow rate through said choke line,

a method of simulation comprising the steps of,

implementing simulated well conditions characteristic of a well control event,

permitting rig crew to perform well control procedures upon said well control system, and

reviewing rig data obtained after rig crew performance of said well control procedures.

40. A well control system comprising,

a blow-out preventer (32) arranged and designed to close a well bore annulus (18) of a well 12 from atmosphere only at a time when drilling is ceased,

a choke line (56) coupled between said well bore annulus and a surface fluid reservoir (42),

an outlet flow rate measurement device (50) disposed in said choke line, said outlet flow rate measurement device arranged and designed to measure flow rate through said choke line and to generate a signal F_out(t) representative of actual choke line flow rate as a function of time (t),

a fluid pump (40) in fluid communication with said surface fluid reservoir (42), and

a flow control device (70) disposed in said choke line and arranged and designed to control fluid flow rate through said choke line.