Abstract: Apparatuses are disclosed for providing directional control of bore drilling equipment. In an embodiment, the apparatus includes a hydraulic pump having an input shaft for receiving an input torque from a drill pipe and being connected in use to a drilling head. In addition, the apparatus includes control arrangement for varying the rate of fluid flow through the pump. The control arrangement includes a closed loop oil-filled system including the hydraulic pump and a main valve. Oil from the pump is routed through the main valve before returning to a pump input. In addition, the control arrangement includes an orifice control system which is operable to control the position of the main valve in response to an input signal from a control processor.

Abstract: Apparatuses are disclosed for providing directional control of bore drilling equipment. In an embodiment, the apparatus includes a hydraulic pump having an input shaft for receiving an input torque from a drill pipe and being connected in use to a drilling head. In addition, the apparatus includes control arrangement for varying the rate of fluid flow through the pump. The control arrangement includes a closed loop oil-filled system including the hydraulic pump and a main valve. Oil from the pump is routed through the main valve before returning to a pump input. In addition, the control arrangement includes an orifice control system which is operable to control the position of the main valve in response to an input signal from a control processor.

Abstract: A borehole cutting assembly for directional cutting in a borehole, the assembly comprising an input pipe and a cutting head rotatably mounted on the input pipe such that the orientation of the cutting head relative to the input pipe can be altered to determine the direction of cutting of the borehole. A cutting tool and cutting tool motor are mounted on the cutting head to enable the cutting tool to be rotatably driven relative to the cutting head so that when the cutting tool is loaded in use the cutting head is subject to a tool reaction torque that acts to rotate the cutting head to change the orientation of the cutting head. The cutting head is rotatably mounted on the input pipe by a controlled torque coupling comprising a progressive cavity pump having a rotor and a stator each provided with drive formations arranged to define a fluid flow cavity therebetween. Rotation of the rotor relative to the stator forces fluid flow through the cavity to counteract the tool reaction torque.

Abstract: A borehole cutting assembly for directional cutting in a borehole, the assembly comprising an input pipe and a cutting head rotatably mounted on the input pipe such that the orientation of the cutting head relative to the input pipe can be altered to determine the direction of cutting of the borehole. A cutting tool and cutting tool motor are mounted on the cutting head to enable the cutting tool to be rotatably driven relative to the cutting head so that when the cutting tool is loaded in use the cutting head is subject to a tool reaction torque that acts to rotate the cutting head to change the orientation of the cutting head. The cutting head is rotatably mounted on the input pipe by a controlled torque coupling comprising a progressive cavity pump having a rotor and a stator each provided with drive formations arranged to define a fluid flow cavity therebetween. Rotation of the rotor relative to the stator forces fluid flow through the cavity to counteract the tool reaction torque.

Abstract: Drilling means for directional drilling in a bore hole comprising a drill pipe and a drilling head, including a slippable clutch device linking the drill pipe and said drilling head such that torque due to rotation of said drill pipe can be controllably applied to said drilling head through at least partial engagement of said clutch, and control means operable to sense an actual orientation angle of said drilling head and compare said actual orientation angle with a required orientation angle adjustably set in said control means and to control said slippable clutch such that when the actual orientation angle and the required orientation angle are the same, the slip torque of the slipping clutch equals the motor reaction torque, so maintaining the orientation angle of the drilling tool at said required orientation angle.

Abstract: A down-hole drilling assembly (12, 16) and control system (120) therefor, for directional drilling including a bent housing of a bottom hole assembly (18), utilizing a gearbox (102) to derive a higher speed (about 600 r.p.m.) rotational drive (104) from the drill string (10) to drive a drilling bit (20) via an electromagnetic clutch (110, 112) controlled by the control system (120) such that the clutch balances reaction torque when the orientation angle of the bent housing is correct.

Abstract: A down-hole drilling assembly (12,16) and control system (120) therefor, for directional drilling including a bent housing of a bottom hole assembly (18), utilising a gearbox (102) to derive a higher speed (about 600 r.p.m.) rotational drive (104) from the drill string (10) to drive a drilling bit (20) via an electromagnetic clutch (110, 112) controlled by the control system (120) such that the clutch balances reaction torque when the orientation angle of the bent housing is correct.

Abstract: Drilling means for directional drilling in a bore hole comprising a drill pipe and a drilling head, including a slippable clutch device linking the drill pipe and said drilling head such that torque due to rotation of said drill pipe can be controllably applied to said drilling head through at least partial engagement of said clutch, and control means operable to sense an actual orientation angle of said drilling head and compare said actual orientation angle with a required orientation angle adjustably set in said control means and to control said slippable clutch such that when the actual orientation angle and the required orientation angle are the same, the slip torque of the slipping clutch equals the motor reaction torque, so maintaining the orientation angle of the drilling tool at said required orientation angle.

Abstract: Inclination and high side angle of a borehole is measured by a tool that may be positioned inside a drill string and lowered into the borehole. The tool includes three gravity transducers positioned in a novel array. The transducers are positioned in a case whose axis coincides with that of the borehole and are arranged with their axes angularly displaced from each other around the case axis by approximately 120 degrees and from the case axis by approximately 45 degrees. An array of fluxgate magnetic transducers may be added to the apparatus to provide combination surveying and steering capability.

Abstract: A linear accelerometer comprises a proof mass in the form of a permanent bar magnet located in a tube containing a magnetic fluid such as a liquid with particles of magnetic material suspended therein. A servo circuit responsive to A.C. energized sensing coils is used to energize a D.C. electromagnet to maintain the proof mass in a central position in the tube.

Abstract: The electrical power required to drive downhole drilling tools and/or measuring instruments is obtained using means responsive to turbulence in the mud flow past a unit forming part of the drill string. The responsive means may comprise a piezo-electric disc connected to rectifying and smoothing circuits whereby a D.C. output is obtained.

Abstract: Apparatus is provided for measuring both the angle between the vertical and a particular axis of a body and the azimuth angle of the displacement of such axis from the vertical. The body houses a trasnducer having a bar magnet mounted on the free end of a pendulum beam and confronting four solenoids forming two differential fluxgate pairs disposed symmetrically with respect to the neutral position of the pendulum beam. The two differential fluxgate pairs are preferably so interconnected that the magnetic flux in each fluxgate pair is equal to zero.