Directional borehole drilling system and method

• US 6,484,819 B1
• Filed: 10/04/2000
• Issued: 11/26/2002
• Est. Priority Date: 11/17/1999
• Status: Expired due to Fees

• Current Assignee: William Harrison
• Original Assignee: William Harrison
• Inventors: Harrison, William H.
• Primary Examiner(s): Bagnell, David
• Assistant Examiner(s): GAY, JENNIFER HAWKINS
• Application Number:
  US09/679,180
• Time in Patent Office: 783 Days
• Field of Search: 175/279, 175/331, 175/342, 175/61, 175/73, 175/40, 175/45, 175/273, 175/24, 175/26, 166/250.01, 166/66, 166/50, 166/313
• US Class Current: 175/61
• CPC Class Codes: E21B 10/20 characterised by detachable or adjustable parts, e.g. legs or axles
• CPC Class Codes: E21B 44/005 Below-ground automatic control systems
• CPC Class Codes: E21B 47/022 of the borehole, e.g. using geomagnetism
• CPC Class Codes: E21B 7/064 specially adapted drill bits therefor

Abstract

A directional borehole drilling system employs a controllable drill bit, which includes one or more drilling surfaces which are dynamically positionable in response to respective command signals. Instrumentation located near the bit measures present position when the bit is static, dynamic and drilling surface position information when the bit is rotating, and stores a desired trajectory. This data is processed to determine the error between the present position and the desired trajectory, and the position of one or more of the bit'"'"'s drilling surfaces is automatically changed as needed to make the bit dig in the direction necessary to reduce the error. The controllable drill bit preferably comprises three cone assemblies mounted about the bit'"'"'s central axis, each of which includes a cone and an eccentric cam that rotate about a common axle. In response to a command signal, the cam is locked to the cone to cause concentric rotation of the cone, or locked to the axle to cause eccentric rotation of the cone—which causes the bit to dig in a preferred direction.

Claims

1. A directional borehole drilling system, comprising:

at least one sonde for mounting within a drill string which is coupled to a controllable drill bit that includes one or more drilling surfaces that are dynamically positionable in response to respective command signals, said drill bit having associated present position, toolface angle, and angular position parameters, said at least one sonde comprising;

a storage medium which contains information that represents a desired drill bit trajectory,

instrumentation which determines the present position of said bit when said bit is in a static position,

instrumentation which determines said bit'"'"'s dynamic toolface angle when said bit is rotating, and

instrumentation which determines the dynamic angular positions of said positionable drilling surfaces when said bit is rotating, and

a processor which receives said present position, dynamic toolface, and dynamic angular position information from said instrumentation, determines the error between said present position and said desired trajectory, and provides said command signals to said controllable drill bit such that said drill bit bores in the direction necessary to reduce said error.

2. The borehole drilling system of claim 1, further comprising said controllable drill bit, said drill bit comprising:

a plurality of cone assemblies mounted about a central axis, each of which rotates about a respective axle and thereby drills a borehole when said bit is driven to rotate about said central axis, and

at least one mechanism coupled to respective ones of said cone assemblies which is actuated in response to a respective one of said command signals, said at least one mechanism arranged to force its respective cone assembly to rotate eccentrically about its axle when actuated, and to allow its respective cone assembly to rotate concentrically about its axle when not actuated.

3. The borehole drilling system of claim 2, wherein said controllable drill bit comprises three cone assemblies mounted about said central axis and three of said mechanisms coupled to respective ones of said cone assemblies.

4. The borehole drilling system of claim 2, wherein each of said mechanisms comprises:

an eccentric cam which rotates about the axle of said mechanism'"'"'s respective cone assembly and is positioned between said cone assembly'"'"'s axle and said cone assembly,

a means for locking said cam to said cone assembly such that, when said cam is locked to said cone assembly, said cam and said cone assembly rotate together about said axle concentrically, and

a means for locking said cam to said axle such that, when said cam is locked to said axle, said cone assembly rotates about said axle eccentrically.

5. The borehole drilling system of claim 4, wherein said means for locking said cam to said axle comprises an extendible pawl coupled at one end to said axle, which, when extended, mechanically couples said cam to said axle.

6. The borehole drilling system of claim 5, further comprising a solenoid which extends said pawl to couple said cam to said axle when actuated in response to a respective one of said command signals.

7. The borehole drilling system of claim 6, wherein said means for locking said cam to said cone assembly comprises a spring which rotates with said cone assembly, said spring arranged to force said pawl to retract to uncouple said cam from said axle and to couple said cone assembly to said cam.

8. The borehole drilling system of claim 4, wherein said instrumentation which determines the dynamic bit toolface angle comprises a plurality of flux-gate magnetometers contained within said sonde and said instrumentation which determines the dynamic drilling surface position comprises a plurality of angular position sensors positioned near respective cams.

9. The borehole drilling system of claim 4, wherein said instrumentation which determines the dynamic bit toolface angle comprises a plurality of accelerometers which are filtered with respective rate gyros and said instrumentation which determines the dynamic drilling surface position comprises a plurality of angular position sensors positioned near respective cams.

10. The borehole drilling system of claim 4, wherein said instrumentation which determines the dynamic bit toolface angle comprises a plurality of flux-gate magnetometers and said instrumentation which determines the and dynamic drilling surface position comprises a plurality of optical encoders positioned near respective cams.

11. The borehole drilling system of claim 4, wherein said controllable drill bit and said each of said cone assemblies have respective circumferences, said controllable drill bit and said cone assemblies arranged such that the ratio of said drill bit circumference to the circumference of any of said cone assemblies is or approaches an irrational number.

12. The borehole drilling system of claim 1, wherein said instrumentation which determines present position comprises a plurality of accelerometers, a plurality of magnetometers, and a means for determining the length of pipe which has been added to said drill string since the previous determination of present position.

13. The borehole drilling system of claim 12, further comprising a transmitter located near the surface end of said drill string from which the length of pipe added to said drill string is transmitted to a receiver located near said controllable drill bit.

14. The borehole drilling system of claim 13, wherein said storage medium is coupled to said receiver and said desired drill bit trajectory information is conveyed to said storage medium via said transmitter and receiver.

15. The borehole drilling system of claim 1, wherein said desired drill bit trajectory is preloaded into said storage medium.

16. A directional borehole drilling system, comprising:

at least one sonde for mounting within a drill string which is coupled to a controllable drill bit that includes one or more drilling surfaces that are dynamically positionable in response to respective command signals, said drill bit having associated present position and toolface angle parameters, said at least one sonde comprising;

a storage medium which contains information that represents a desired drill bit trajectory,

instrumentation which determines the present position of said bit when said bit is in a static position, and the bit'"'"'s dynamic toolface angle and the positions of said positionable drilling surfaces when said bit is rotating,

a processor which receives said present position, dynamic toolface, and drilling surface position information from said instrumentation, determines the error between said present position and said desired trajectory, and provides said command signals to said controllable drill bit such that said drill bit bores in the direction necessary to reduce said error,

a controllable drill bit, said drill bit comprising;

a plurality of cone assemblies mounted about a central axis, each of which rotates about a respective axle and thereby drills a borehole when said bit is driven to rotate about said central axis, and

at least one mechanism coupled to respective ones of said cone assemblies which is actuated in response to a respective one of said command signals, said at least one mechanism arranged to force its respective cone assembly to rotate eccentrically about its axle when actuated, and to allow its respective cone assembly to rotate concentrically about its axle when not actuated, wherein each of said mechanisms comprises;

an eccentric cam which rotates about the axle of said mechanism'"'"'s respective cone assembly and is positioned between said cone assembly'"'"'s axle and said cone assembly,

a means for locking said cam to said cone assembly such that, when said cam is locked to said cone assembly, said cam and said cone assembly rotate together about said axle concentrically, and

a means for locking said cam to said axle such that, when said cam is locked to said axle, said cone assembly rotates about said axle eccentrically, wherein each of said mechanisms is arranged to lock its cone assembly to said cam after its cone assembly has completed one revolution about said axle with said cam locked to said axle.

17. A directional borehole drilling system, comprising:

at least one sonde for mounting within a drill string which is coupled to a controllable drill bit that includes one or more drilling surfaces that are dynamically positionable in response to respective command signals, said drill bit having associated present position and toolface angle parameters, said at least one sonde comprising;

a storage medium which contains information that represents a desired drill bit trajectory,

instrumentation which determines the present position of said bit when said bit is in a static position, and the bit'"'"'s dynamic toolface angle and the positions of said positionable drilling surfaces when said bit is rotating,

a processor which receives said present position, dynamic toolface, and drilling surface position information from said instrumentation, determines the error between said present position and said desired trajectory, and provides said command signals to said controllable drill bit such that said drill bit bores in the direction necessary to reduce said error,

a controllable drill bit, said drill bit comprising;

a plurality of cone assemblies mounted about a central axis, each of which rotates about a respective axle and thereby drills a borehole when said bit is driven to rotate about said central axis, and

at least one mechanism coupled to respective ones of said cone assemblies which is actuated in response to a respective one of said command signals, said at least one mechanism arranged to force its respective cone assembly to rotate eccentrically about its axle when actuated, and to allow its respective cone assembly to rotate concentrically about its axle when not actuated, wherein each of said mechanisms comprises;

an eccentric cam which rotates about the axle of said mechanism'"'"'s respective cone assembly and is positioned between said cone assembly'"'"'s axle and said cone assembly,

a means for locking said cam to said cone assembly such that, when said cam is locked to said cone assembly, said cam and said cone assembly rotate together about said axle concentrically,

a means for locking said cam to said axle such that, when said cam is locked to said axle, said cone assembly rotates about said axle eccentrically, said means for locking said cam to said axle comprising an extendible pawl coupled at one end to said axle, which, when extended, mechanically couples said cam to said axle,

a solenoid which extends said pawl to couple said cam to said axle when actuated in response to a respective one of said command signals,

a spring which rotates with said cone assembly, said spring arranged to force said pawl to retract to uncouple said cam from said axle and to couple said cone assembly to said cam, and

a roller affixed to said spring and a plate coupled to said cam, said plate including a semi-circular slot aligned with said roller, said solenoid arranged such that said pawl extends into said slot when said solenoid is actuated and stops said plate and thereby said cam from rotating, said spring and roller arranged such that, when said solenoid is not actuated, said roller forces said pawl out of said slot and catches the edge of said slot to lock said cam to said cone assembly as said roller rotates with said cone.

18. A directional borehole drilling system, comprising:

at least one sonde for mounting within s drill bit that includes one or more drilling surfaces that are dynamically positionable in response to respective command signals, said drill bit having associated present position and toolface angle parameters, said at least one sonde comprising;

a storage medium which contains information that represent a desired drill bit trajectory,

instruments which determines the present position of the said bit when said bit is in a static position, and the bit'"'"'s dynamic toolface angle and the position, of said positionable drilling surfaces when said bit is rotating

a processor which receives said present position, dynamic toolface, and drilling surface position information from said instrumentation, determines the error between said present position and said desired trajectory, and provides said command signals to said controllable drill bit such that said drill bit bores in the direction necessary to reduce said error,

a controllable drill bit, said drill bit comprising;

a plurality of cone assemblies mounted about a central axis, each of which rotates about a respective axle and thereby drills a borehole when said bit is driven to rotate about said central axis, and

at least one mechanism coupled to respective to respective ones of said cone assemblies which is actuated in response to a respective one of said command signals, said at least one mechanism arranged to force its respective cone assembly to rotate eccentrically about its axle when actuated, and to allow its respective cone assembly to rotate concentrically about its axle when not actuated, where each of said mechanisms comprises;

an eccentric cam which rotates about the axle of said mechanism'"'"'s respective cone assembly and is positioned between said cone assembly'"'"'s axle and said cone assembly,

a means for locking said cam to said cone assembly, said cam and said cone assembly rotate together about said axle concentrically, and

a means for locking said cam to said axle such that, when said cam is locked axle, said cone assembly rotates about said axle eccentrically,

wherein said instrumentation which determines dynamic bit toolface angle and drilling surface position comprises a plurality of synchros positioned near respective cams, and a plurality of magnetometers.

19. A directional borehole drilling system, comprising:

a controllable drill bit having associated present position, toolface angle, and angular position parameters, said bit comprising;

a plurality of cone assemblies mounted about a central axis, each of which rotates about a respective axle and thereby drills a borehole when said bit is driven to rotate about said central axis,

at least one mechanism coupled to respective ones of said cone assemblies which is actuated in response to a respective command signal, said at least one mechanism arranged to force its respective cone assembly to rotate eccentrically about its axle when actuated and to allow its respective cone assembly to rotate concentrically about its axle when not actuated,

a drill string coupled to said controllable drill bit,

a driving means coupled to said drill string which drives said bit to rotate about said central axis, and

at least one sonde within said drill string which comprises;

a storage medium which contains information that represents a desired drill bit trajectory,

a first instrumentation package which determines the present position of said bit when said bit is in a static position,

a second instrumentation package which determines the dynamic toolface angle of said bit when said bit is rotating,

a third instrumentation package which determines the dynamic angular positions of the cone assemblies coupled to said mechanisms when said bit is rotating about said central axis, and

a processor which receives said present position, dynamic toolface, and dynamic angular position information from said instrumentation, determines the error between said present position and said desired trajectory, and provides said command signals to said to said controllable drill bit such that said drill bit bores in the direction necessary to reduce said error.

20. A directional borehole drilling system, comprising:

a controllable drill bit, said bit comprising;

a plurality of cone assemblies mounted about a central axis, each of which rotates about a respective axle and thereby drills a borehole when said bit is driven to rotate about said central axis,

at least one mechanism coupled to respective ones of said cone assemblies which is actuated in response to a respective command signal, said at least one mechanism arranged to force its respective cone assembly to rotate eccentrically about its axle when actuated and to allow its respective cone assembly to rotate concentrically about its axle when not actuated,

a drill string coupled to said controllable drill bit,

a driving means coupled to said drill string which drives said bit to rotate about said central axis, and

at least one sonde within said drill string which comprises;

a storage medium which contains information that represents a desired drill bit trajectory,

a first instrumentation package which determines the present position of said bit when said bit is in a static position,

a second instrumentation package which determines the dynamic toolface angle of said bit and the positions of the cone assemblies coupled to said mechanisms when said bit is rotating about said central axis, and

a processor which receives said present position and cone assembly position information from said instrumentation, determines the error between said present position and said desired trajectory, and provides said command signals to said to said controllable drill bit such that said drill bit bores in the direction necessary to reduce said error,

wherein each of said mechanisms comprises;

an eccentric cam mounted on said axle,

a spring and a roller coupled to and rotating with said cone assembly,

a plate coupled to said cam which includes a semicircular slot aligned with said roller, and

a solenoid affixed to said axle and arranged to extend a pawl into said slot when actuated to stop said plate and thereby said cam from rotating, said spring and roller arranged such that, when said solenoid is not actuated, said roller forces said pawl out of said slot and catches the edge of said slot to lock said cam to said cone assembly as said roller rotates with said cone.

21. A method of directional drilling in a bore-hole, comprising the steps of:

providing a controllable drill bit which comprises a plurality of cone assemblies mounted about a central axis, each of which rotates about a respective axle and can be made to rotate either concentrically or eccentrically about said axle, said drill bit having associated present position and toolface angle parameters and said cone assemblies having associated angular positions,

determining a desired trajectory for said drill bit,

determining the present position of said drill bit,

determining the error between said present position and said desired trajectory,

rotating said drill bit about said central axis,

determining the dynamic toolface angle of said bit,

determining the dynamic angular positions of said cone assemblies, and

causing, based on said present position, said dynamic toolface angle, and said angular position data, at least one of said cone assemblies to rotate eccentrically about its axle such that drill bit bores in a direction necessary to reduce said error.

22. The method of claim 21, wherein said controllable drill bit includes respective mechanisms coupled to respective ones of said cone assemblies, each of said mechanisms comprising:

a cam which rotates about the axle of said mechanism'"'"'s respective cone assembly and is positioned between said cone assembly'"'"'s axle and said cone assembly,

a means for locking said cam to said cone assembly such that, when said cam is locked to said cone assembly, said cam and said cone assembly rotate together about said axle concentrically, and

a means for locking said cam to said axle such that, when said cam is locked to said axle, said cone assembly rotates about said axle eccentrically,

each of said cone assemblies made to rotate concentrically by locking its cam to said cone assembly and made to rotate eccentrically by locking its cam to its axle.

23. A controllable drill bit which includes one or more drilling surfaces which are positionable in response to a command signal, said bit comprising:

a plurality of cone assemblies mounted about a central axis, each of said cone assemblies arranged to rotate about a respective axle as said bit is rotated about said central axis,

a plurality of mechanisms coupled to respective ones of said cone assemblies, each of which is actuated in response to a respective command signal, each mechanism arranged to force its respective cone assembly to rotate eccentrically about its axle when actuated and to allow its respective cone assembly to rotate concentrically about its axle when not actuated, each of said mechanisms comprising;

an eccentric cam mounted on said axle,

a spring and a roller coupled to and rotating with said cone assembly,

a circular plate coupled to said cam which includes a semi-circular slot aligned with said roller, and

a solenoid affixed to said axle and arranged to extend a pawl into said slot when said mechanism is actuated to stop said plate and thereby said cam from rotating, said spring and roller arranged such that, when said mechanism is not actuated, said roller forces said pawl out of said slot and catches the edge of said slot to lock said cam to said cone assembly as said roller rotates with said cone.

24. The controllable drill bit of claim 23, wherein said axle is cylindrical and has a longitudinal axis which runs down its center, said solenoid mounted within said axle and aligned along said longitudinal axis, further comprising a lever which is fixed at one end and movable at its other end and arranged to be pushed at its center when said mechanism is actuated, said pawl mounted to said movable end of said lever such that it moves along an axis parallel to but offset from said longitudinal axis when extended.

25. The controllable drill bit of claim 23, wherein the diameter of said plate is greater than that of said cam and said semi-circular slot is located outside the outer diameter of said cam, said solenoid mounted outside the outer diameter of said axle.

26. The controllable drill bit of claim 23, further comprising a plurality of angular position sensors mounted to respective axles, each of said cams having an index notch aligned to rotate past a respective one of said sensors to indicate its angular position.

27. The controllable drill bit of claim 23, further comprising a plurality of optical encoders mounted to respective axles and arranged to indicate the angular positions of respective cams.

28. A controllable drill bit which includes one or more drilling surfaces which are positionable in response to a command signal, said bit comprising:

a plurality of cone assemblies mounted about a central axis, each of said cone assemblies arranged to rotate about a respective cylindrical axle as said bit is rotated about said central axis,

a plurality of mechanisms coupled to respective ones of said cone assemblies, each of which is actuated in response to a respective command signal, each mechanism arranged to force its respective cone assembly to rotate eccentrically about its axle when actuated and to allow its respective cone assembly to rotate concentrically about its axle when not actuated, each of said mechanisms comprising;

an eccentric cam mounted on said axle,

a spring and a roller coupled to and rotating with said cone assembly,

a circular plate coupled to said cam which includes a semi-circular slot near its outer diameter which is aligned with said roller,

a solenoid mounted within said axle and aligned along its longitudinal axis and which is actuated when said mechanism is actuated,

a lever which is fixed at one end and movable at its other end and arranged to be pushed at its center when said solenoid is actuated, and

a pawl which is mounted to said movable end of said lever such that it is extended along an axis parallel to but offset from said longitudinal axis when said solenoid is actuated, said pawl further arranged to extend into said slot when actuated to stop said plate and thereby said cam from rotating, said spring and roller arranged such that, when said solenoid is not actuated, said roller forces said pawl out of said slot and catches the edge of said slot to lock said cam to said cone assembly as said roller rotates with said cone.

29. A controllable drill bit which includes one or more drilling surfaces which are positionable in response to a command signal, said bit comprising:

a plurality of cone assemblies mounted about a central axis, each of said cone assemblies arranged to rotate about a respective cylindrical axle as said bit is rotated about said central axis,

a plurality of mechanisms coupled to respective ones of said cone assemblies, each of which is actuated in response to a respective command signal, each mechanism arranged to force its respective cone assembly to rotate eccentrically about its axle when actuated and to allow its respective cone assembly to rotate concentrically about its axle when not actuated, each of said mechanisms comprising;

an eccentric cam mounted on said axle,

a spring and a roller coupled to and rotating with said cone assembly,

a circular plate coupled to said cam which includes a semi-circular slot near its outer diameter which is aligned with said roller,

a solenoid mounted outside said axle which is actuated when said mechanism is actuated, and

a pawl which is extended into said slot when said solenoid is actuated to stop said plate and thereby said cam from rotating, said spring and roller arranged such that, when said solenoid is not actuated, said roller forces said pawl out of said slot and catches the edge of said slot to lock said cam to said cone assembly as said roller rotates with said cone.