Directional drilling system with eccentric mounted motor and biaxial sensor and method
First Claim
1. A directional drilling system of the type which includes a drill string having a plurality of drill stems joined together for drilling a bore through the earth in a prescribed direction comprising:
- a drilling platform disposed at a starting point;
a frame carried by said platform;
a carriage carried by said frame;
a drill string drive motor carried by said carriage for coupling with and rotating said drill string;
carriage advance means for moving said carriage longitudinally along said platform as said drill string drive motor rotates the drill string;
a drilling head carried at an end of said drill string;
a drill bit motor carried by said drilling head;
a drill bit carried by said drill bit motor;
eccentric mounting means for mounting said drill bit eccentrically in said drilling head to define an eccentric position in which said drill bit overcuts relative to a diameter of said drilling head;
indicator means for indicating the rotational angular position of said eccentric position of said drill bit relative to said drill string;
position measuring means for measuring the position of said drilling head and determining deviations in the position of said drilling head with reference to a desired drill string path;
control means for varying the relative speeds of said drill string drive motor and said drill bit motor to control the eccentric position of said drill bit to overcut in a desired direction and control the direction of said drilling head and drill string in response to said drill bit eccentric position to eliminate said deviations in said drilling head position.
2 Assignments
0 Petitions
Accused Products
Abstract
Apparatus and method for a directional drilling system is disclosed wherein a concrete pit is poured at a reference entry angle in the earth so that a drilling platform cartridge inserted into the concrete pit is set at the desired entry angle. A frame, including elongated guide ways extending between ends of the platform cartridge, guides a carriage that advances a drill string through the earth at the reference angle. Preferably, a drilling head at the end of the drill string and the remainder of the drill string are rotated by a drive motor carried on the carriage. A drill bit and drill bit motor are mounted coaxially and eccentric with respect to the drilling head. The center axis of the drill bit and drill bit motor, and the center axis of the rotating drilling head are offset and define a known relationship. The offset relationship between the center axis of the drill bit and drilling head defines an eccentric position in which the drill bit overcuts relative to the outside diameter of the drilling head in an eccentric position. As long as the drilling bit and drilling head rotate simultaneously, movement of the drill string is controlled generally in a straight line. If rotation of the drilling head is stopped, the drill string is steered in the direction of the eccentric position of the drill bit since there is no clearance on the opposing side of the drilling head.
63 Citations
81 Claims
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1. A directional drilling system of the type which includes a drill string having a plurality of drill stems joined together for drilling a bore through the earth in a prescribed direction comprising:
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a drilling platform disposed at a starting point; a frame carried by said platform; a carriage carried by said frame; a drill string drive motor carried by said carriage for coupling with and rotating said drill string; carriage advance means for moving said carriage longitudinally along said platform as said drill string drive motor rotates the drill string; a drilling head carried at an end of said drill string; a drill bit motor carried by said drilling head; a drill bit carried by said drill bit motor; eccentric mounting means for mounting said drill bit eccentrically in said drilling head to define an eccentric position in which said drill bit overcuts relative to a diameter of said drilling head; indicator means for indicating the rotational angular position of said eccentric position of said drill bit relative to said drill string; position measuring means for measuring the position of said drilling head and determining deviations in the position of said drilling head with reference to a desired drill string path; control means for varying the relative speeds of said drill string drive motor and said drill bit motor to control the eccentric position of said drill bit to overcut in a desired direction and control the direction of said drilling head and drill string in response to said drill bit eccentric position to eliminate said deviations in said drilling head position. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15)
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16. A directional drilling system of the type which includes a drill string having a plurality of drill stems joined together for drilling a bore through the earth in a prescribed direction comprising:
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a drilling platform having two spaced apart end walls carried by said platform; a frame carried by said platform; a carriage carried by said frame; a drill string drive motor carried by said carriage for rotating said drill string; coupling mans for coupling one of said drill stems to said drill string drive motor; and carriage advance means for moving said carriage longitudinally along said frame and platform as said drill string drive motor rotates the drill string. - View Dependent Claims (17, 18, 19, 20, 21, 22, 23, 24, 25, 26, 27, 28, 29, 30, 31)
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32. A directional drilling system of the type which includes a drill string having a plurality of drill stems joined together for drilling a bore through the earth in a prescribed direction comprising:
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a drilling head carried at an end of said drill string; a drive motor for causing said drilling head to be rotated; a drill bit motor carried by said drilling head; eccentric mounting means for mounting said drill bit eccentrically in said drilling head to define an eccentric position in which said drill bit overcuts relative to a diameter of said drilling head; control means for varying the relative rotational speeds of said drill string drive motor and said drill bit motor to alter the eccentric position of said drill bit to overcut in a desired direction and control the direction of said drilling head and drill string. - View Dependent Claims (33, 34, 35, 36, 37, 38, 39, 40)
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41. Directional drilling apparatus of the type which includes a drill string having a plurality of drill stems joined together for drilling a bore through the earth in a prescribed direction, a drilling head disposed at an end of said drill string carrying a rotating drill bit for cutting said bore, and a guidance system for controlling the direction of the drill string, wherein said apparatus comprises:
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means for rotating said drilling head; eccentric mounting means for mounting said drill bit eccentrically in said drilling head to define an eccentric position in which said drill bit overcuts said bore relative to a diameter of said drilling head; angle sensor means for measuring a first and second position angle of said drilling head and generating first and second angle signals corresponding to the first and second position angles; distance measuring means for measuring the distance travelled by drill head from a starting point and generating a corresponding distance signal; computer means for processing said first and second angle signals, and distance signal to compute the horizontal and vertical position of said drilling head and deviations of said drilling head from horizontal and vertical positions along a desired drill path; and control means for varying the relative rotational speeds of said drilling head and drill bit to control the eccentric position of said drill bit and steer said drilling head and drill string in a desired direction to eliminate said deviations and steer said drill string along said desired drill path. - View Dependent Claims (42, 43, 44, 45, 46, 47, 48, 49, 50, 51, 52, 53, 54)
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55. A directional drilling system having a drill string with a plurality of drill stems joined together for drilling a bore through the earth in a desired direction comprising:
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drive means for rotating at least a drilling head carried at an end of said drill string having a central axis; a drill bit carried by said drilling head having a center axis displaced from the center axis of said drilling head so that said drill bit is carried at an eccentric position by said drilling head in which said drill bit overcuts said bore relative to an outside diameter of said drilling head; means for rotating said drill bit independently of said drilling head; means for indicating the eccentric position of said drill bit in reference to said drilling head; position measuring means for determining the position of said drilling head relative to a desired drill string direction and path, and determining deviations of said drilling head from said path; and control means for controlling the relative rotational speeds of said drilling head and drill bit relative to each other to control the eccentric position of said drill bit to overcut said bore in a desired direction and steer said drill string in that direction to eliminate said deviations and steer said drill string along said desired drill path. - View Dependent Claims (56, 57, 58, 59)
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60. Directional drilling apparatus of the type which includes a drill string having a plurality of drill stems joined together for drilling a bore through the earth in a prescribed direction, a drilling head carrying a rotating drill bit for cutting said bore;
- and a guidance system for controlling the direction of the drill string;
wherein said apparatus comprises;an angle sensor means carried by said drilling head for measuring horizontal and vertical position angles of said drilling head and generating first and second angle signals corresponding to said horizontal and vertical position angles of said drilling head; distance measuring means for measuring the distance said drilling head has travelled and generating a distance signal; computer means for processing said first and second angle signals and said distance signals for computing deviations of said drilling head and drill string from a desired drill path; said angle sensor means including an angular rate sensor means for measuring changes about two orthogonal axes, means for mounting said angular rate sensor for continuous rotation with said drilling head, and said rotating angular rate sensor means senses changes about said two axes for generating said horizontal and vertical angular rate signals corresponding to changes in direction per unit time about said first and second axes; and encoder means for determining the rotational position and timing of said angular rate sensor and said drilling head while said angular rate sensor and drilling head are rotating together. - View Dependent Claims (61, 62, 63, 64, 65, 66, 67, 68, 69, 70, 71, 72)
- and a guidance system for controlling the direction of the drill string;
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73. A method of guiding a directional drill string of the type which has a plurality of drill stems joined together, a drilling head carried at the end of said drill stem having a central axis, a drill bit carried by said drilling head for cutting a bore in the earth;
- wherein said method comprises;
mounting an angular rate sensor means in said drilling head for measuring angular rate about a first and second sensing axis per unit of time; rotating said single axis angular rate sensor means continuously with said drilling head while cutting said bore about said central axis of said drilling head to measure angular rate about said first and a second sensing axes which intersect said center axis of said drilling head and generating first and second angular rate signals corresponding to horizontal and vertical angular rates; determining the rotational position of said angular rate sensor means as it rotates with said drilling head through four quadrants and generating sensor quadrant position and timing signals corresponding to the quadrant position and timing of said angular rate sensor through said quadrant as said angular rate sensor rotates with said drilling head; integrating said first and second angular rate signals and said sensor quadrant position and timing signals to generate first and second position angle signals corresponding to the horizontal position angle and vertical position angles of said drilling head; determining the distance said drilling head has travelled from a starting point and instantaneously generating a distance travelled signal; processing said horizontal and vertical position angles with said distance signal to compute horizontal and vertical positions; comparing said horizontal and vertical positions to a desired drill path and calculating deviations from said path; and steering said drilling head to eliminate said deviations. - View Dependent Claims (74, 75)
- wherein said method comprises;
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76. A method for steering a directional drilling device of the type which includes a drill string having a drilling head for cutting a bore through the earth in a prescribed direction comprising:
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rotating a drilling head carried at an end of said drill string; mounting a rotating drill bit eccentrically in said drilling head so that a center axis of said drill bit and drilling head have a known relationship; and
said drill bit has an eccentric position in which said drill bit overcuts said bore relative to a diameter of said drilling head; andcontrolling the relative rotational speeds of said drilling head and drill bit to alter the eccentric position of said drill bit to overcut said bore in a desired direction and control the direction of said drilling head and drill string. - View Dependent Claims (77)
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78. A method of drilling a bore through the earth in a desired direction using a directional drilling device having a drill string with a drilling head carried at an outer end comprising:
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excavating a pit in the earth at a starting point of said drill string; placing a form in said earth pit at a prescribed inclination corresponding to a desired reference entry angle of said drilling string and drilling head; pouring concrete in said earth pit between said form and the earth to form a concrete pit having a pit opening corresponding to said form, and thereafter removing said form; placing a drilling platform having a shape generally conforming to the shape of said form in said pit opening of said concrete pit so that said platform is set in said concrete pit at said reference entry angle; and assembling said drilling head and drill string on said platform so that said drilling head is oriented in the direction of said reference entry angle. - View Dependent Claims (79, 80, 81)
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Specification