Directional drilling apparatus

Abstract

A pendulum is mounted in the drill pipe close to the drill bit to assume a vertical position in the azimuthal plane of the drill pipe. When the position of the pendulum is such that the inclination of the drill pipe is not a preselected amount or the azimuthal direction of the pipe is not the preselected direction, a lateral force is imposed on the drill bit urging it to drill in a direction that will return the drill pipe to said preselected inclination or azimuthal direction. The pendulum and its associated apparatus is rotated in the direction opposite the direction that the drill pipe is rotated and at the same speed, so that the pendulum is substantially nonrotative relative to the earth.

The invention having been described, what is claimed is: 
     
       1. Apparatus for urging a drill bit connected to a drill string to drill through the earth in a preselected azimuthal direction comprising azimuthal direction sensing means located in the drill string, means responsive to the azimuthal direction sensing means when the azimuthal direction of the pipe string varies from the preselected direction for exerting a lateral force on the drill bit to urge the drill bit to drill in a direction that will return the drill string to the preselected azimuthal direction, and means for rotating the azimuthal direction sensing means relative to the drill string at approximately the speed of rotation of the drill string and in the opposite direction to hold the sensing means substantially non-rotative relative to the earth. 
     
     
       2. The apparatus of claim 1 in which the azimuthal direction sensing means includes a north seeking element. 
     
     
       3. The apparatus of claim 1 .[.further.]. in which the azimuthal direction sensing means includes means for sensing the inclination from the vertical of the drill string and means responsive to said inclination sensing means for exerting a lateral force on the drill bit, when the inclination of the pipe string varies from a preselected angle to urge the drill bit to drill in a direction that will return the drill string to the preselected angle. 
     
     
       4. The apparatus of claim 3 in which the inclination sensing means includes a vertical seeking member that makes an angle with the drill string substantially equal to the angle the drill string makes with the vertical. 
     
     
       5. The apparatus of claim 4 in which the azimuth sensing means includes a north seeking element and said inclination sensing means include a pendulum, means providing a universal connection between the north seeking element and the pendulum to permit the pendulum to seek a vertical position and energize the lateral force producing means when the inclination of the drill pipe and its azimuthal direction vary from said preselected values. 
     
     
       6. The apparatus of claim 5 in which said lateral force producing means for urging the drill bit to drill in the desired direction includes means for providing correction signals in response to the position of the pendulum to energize lateral force producing means to urge the bit either upward, or downward, and to the left or to the right as required to direct the bit through the earth at the preselected inclination and azimuthal direction. 
     
     
       7. The apparatus of claim 5 in which the lateral force producing means urges the bit to move out of axial alignment with the drill string to cause the bit to drill in the desired direction. 
     
     
       8. The apparatus of claim 1 further provided with means providing a continuous lateral force adjacent the drill bit urging the drill bit to change its inclination as it bores through the earth. 
     
     
       9. Apparatus for urging a drill bit connected to a drill string to follow a given angle from the vertical comprising, inclination sensing means located in the drill string to sense the angle the drill string makes with the vertical, means responsive to the inclination of the drill string to exert a lateral force on the drill bit, when the inclination is different from a preselected angle, to urge the bit to drill in a direction that will return the drill string to the preselected angle, and means for rotating the inclination sensing means at approximately the speed of rotation of the drill string and in the opposite direction to keep the sensing means substantially non-rotative relative to the earth. 
     
     
       10. Apparatus for urging a drill bit connected to a drill string to follow a given angle from the vertical comprising, inclination sensing means located in the drill string having a vertical seeking member that makes an angle with the drill string substantially equal to the angle the drill string makes with the vertical, means responsive to the angle the drill string makes with the vertical seeking member for exerting a lateral force on the drill bit, when the angle is different from a preselected angle, to urge the bit to drill in a direction that will return the drill string to the preselected angle, and means for rotating the inclination sensing means at approximately the speed of rotation of the drill string and in the opposite direction to keep the sensing means substantially non-rotative relative to the earth. 
     
     
       11. The apparatus of claim 10 in which the inclination sensing means also includes means for sensing the azimuthal direction the well bore is taking as it is being drilled and in which said force applying means applies a lateral force on the drill bit in response to said azimuthal sensing means to urge the drill bit to maintain a prescribed azimuth as it drills through the earth. 
     
     
       12. The apparatus of claim 10 in which the means for rotating the sensing means includes a fluid motor having a stator and a rotor, the rotor being attached to the drill string for rotation therewith, a source of pressure fluid for rotating the stator relative to the rotor in a direction opposite to the direction of rotation of the drill string, means responsive to rotation controlling the supply of pressurized fluid to the motor to rotate the stator at approximately the speed of rotation of the drill string to cause the stator to be substantially non-rotative relative to the earth, and means connecting the sensing means to the stator. 
     
     
       13. The apparatus of claim 12 in which the pressure fluid controlling means includes a gyroscope connected to the stator and valve means responsive to forces exerted by the gyroscope, when rotated, to control the flow of pressure fluid to the fluid motor. 
     
     
       14. The apparatus of claim 13 in which the wheel of the gyroscope is rotated by a stream of the pressure fluid directed against the wheel. 
     
     
       15. The apparatus of claim 12 in which the azimuth sensing means includes a magnetic compass having a magnetic north seeking element. 
     
     
       16. The apparatus of claim 15 further provided with a second fluid motor having a stator and a rotor, said second motor being mounted with its rotor connected to the stator of the first motor and its stator connected to the north seeking element of the compass, means supplying said second motor with pressure fluid to rotate its stator in a direction opposite the direction of rotation of its rotor and means, responsive to relative movement between the stator and the magnetic north seeking element, controlling the flow of pressure fluid to said second motor to cause the stator to rotate at approximately the same speed as the rotor is rotated by the stator of the first motor and in the opposite direction so the stator is substantially non-rotative relative to the earth and the magnetic north seeking element. 
     
     
       17. The apparatus of claim 10 in which the vertical seeking member of the inclination sensing means comprises a pendulum pivotally mounted to freely seek a vertical hanging position. 
     
     
       18. The apparatus of claim 11 in which the azimuth and angle sensing means includes a magnetic compass having a magnetic north seeking element, a pendulum, means mounting the pendulum for pivotal movement in all directions, means responsive to the position of the pendulum to provide a corrective force when the pendulum is not positioned in a preselected azimuth plane and to provide a corrective force when the pendulum is not at a preselected angle of inclination from the vertical and to provide a zero corrective force when the pendulum is positioned in said preselected azimuthal plane and at said preselected angle of inclination, and means connecting the pendulum mounting means to the north seeking element including means permitting the mounting means to be adjusted to position the pendulum to provide said corrective forces. 
     
     
       19. The apparatus of claim 10 in which the means providing said lateral force on the drill bit includes a tubular sleeve, means mounting the sleeve on the drill string above the drill bit for limited lateral movement relative to the drill pipe, a plurality of fluid operated force transmitting members positioned circumferentially around the drill string between the sleeve and the drill string and means for sequentially supplying said members with pressure fluid to cause said members to exert a lateral force on the drill string to urge the drill bit to drill through the earth in the desired direction. 
     
     
       20. The apparatus of claim 19 in which the force transmitting members are inflatable bladders of flexible material. 
     
     
       21. The apparatus of claim 19 in which said force providing means includes pressure signal passageways, valve means responsive to inclination of said sensing means for controlling the flow of pressure fluid to said pressure signal passageways, said passageways having outlet ports the same radial distance from the longitudinal axis of the drill pipe, a signal distributor member attached to the drill pipe for rotation therewith, said member having conduits therein with inlet ports the same radial distance from the axis of the drill pipe as the outlet ports of the first mentioned passageways, said member being positioned so the inlet ports of the conduits will move past the outlet ports each revolution of the drill pipe to pressurize each of said conduits as its port passes by the outlet ports of the pressure signal passageways that are being supplied with pressure fluid by said valve means, and means responsive to fluid pressure in said conduits for actuating the fluid operated force transmitting members. 
     
     
       22. The apparatus of claim 18 in which said means of providing a corrective force includes pressure signal passageways, valve means actuated by the pendulum to pressurize the proper pressure signal passageways, and means responsive to the pressure signal in said passageways to exert the desired corrective lateral force on said drill bit. 
     
     
       23. The apparatus of claim 22 in which said lateral force exerting means includes a bit sub connecting the drill bit to the drill string, means providing a universal connection between the bit sub and the drill string and means for urging the bit sub to pivot in one direction to move the axis of rotation of the bit out of alignment with the axis of rotation of the drill pipe to urge the bit to drill in a direction that will return the drill string to the desired azimuthal direction and inclination. 
     
     
       24. The apparatus of claim 23 in which the lateral force exerting means includes a plurality of orienting cylinders each connected to one of said pressure signal passgeways, a piston in each cylinder with a rod attached thereto and extending out of said cylinder, a shaft mounted for rotation with a swash plate attached to the shaft at an angle and positioned to be engaged by each rod for downward movement of a rod to cause the swash plate to rotate to position its low side under the downwardly moving rod and thereby rotate the shaft to the desired orientation, a power cylinder having a piston therein slidably connected to the shaft for rotation thereby as the swash plate orients the shaft, means supplying said cylinder with fluid pressure to move said piston downwardly, means actuated by the downwardly moving piston for exerting a lateral force on the bit sub to move the drill bit out of axial alignment with the drill string in the direction to cause the bit to tend to drill in a direction that will return the drill string to the desired preselected inclination and azimuthal direction. 
     
     
       25. The apparatus of claim 10 further provided with means providing a continuous lateral force adjacent the drill bit urging the drill bit to change its azimuthal direction as it bores through the earth. .Iadd. 26. Apparatus for directionally drilling a well bore comprising a drill string extending into the well bore, a drill bit, means connecting the drill bit to the drill string to transmit rotation of the drill string to the drill bit and to allow limited universal pivotal movement of the bit around an axis perpendicular to the longitudinal axis of the drill string, including a bit sub having an upper portion extending above the universal connection into the drill string, means for sensing the inclination of the drill string adjacent the bit, and means responsive to the sensing means for urging the bit to pivot in the desired direction around said axis to change the direction of the well bore, said urging means including a piston mounted in the drill string adjacent the upper portion of the bit sub for rotation relative to the drill string and for axial movement along the longitudinal axis of the drill string toward and away from said upper portion for rotation relative thereto, a cam follower connected to the swivel member, a cam surface on the piston engaging the cam follower to pivot the sub and bit around said axis when the piston is moved axially along the longitudinal axis of the drill string, and means responsive to the sensing means to position the piston to pivot the sub and bit in the desired direction and to move the piston to so pivot the sub and bit. .Iaddend.