Abstract: A method of apparatus for controlling in a wellbore the force applied to a rotating drill bit of the type having fluid circulating through an opening in the lower end thereof. One aspect of the method comprises sensing the torque in the drill bit and varying the flow of the circulating fluid through the drill bit responsive to the torque. Apparatus is provided for maintaining constant torque in the drill bit by varying the fluid flow through the bit, which varies in turn the weight applied to the bit and therefore bit torque.

Abstract: A technique for providing a continuous underground tunnel is disclosed herein. This technique utilizes an elongated boring device including a forward facing, off-axis high pressure fluid jet which is rotated about the elongated axis of the device while the latter is urged forward through the soil, whereby to cause the device to bore a tunnel through the soil as it moves forward. In accordance with one feature of this technique, the boring device is steered by modulating the speed and/or the direction of rotation of its off-axis fluid jet in a way which depends upon the desired direction to be taken by the boring device within the soil. In accordance with another feature of the overall technique, the pitch angle of the boring device, as defined by its elongation axis, is monitored relative to a horizontal ground plane, independent of the roll position of the device.

Abstract: A method and apparatus for controlling the rotational torque of a drill bit powered by a downhole motor. The downhole motor is suspended from a hydraulic ram at the lower end of a string of drill pipe. A torque sensor detects the reactive torque in the downhole motor during drilling. In response to the detected torque level, pressurized drilling fluid from the downhole motor is provided to the hydraulic ram thereby varying the weight applied to the drill bit in order to maintain a constant torque level.

Abstract: A control system guides a boring tool in a borehole. The tool has a longitudinal tool axis and includes a driver for advancing the tool axially through the earth and steering mechanism for directing the motion of the tool relative to the tool axis in response to control signals. The control system includes an axial electromagnetic source for generating an axial alternating magnetic field directed along an axial source axis. A sensing assembly remote from the source means includes first and second pickup coils for sensing the alternating magnetic field. Each of the first and second pickup coils has a respective coil axis and is rigidly mounted in respect to the other with their respective axes at a substantial angle with respect to each other, defining a sensing assembly axis substantially normal to both coil axes. Each coil generates a respective null electrical signal when the lines of magnetic flux at the respective coil are normal to the respective coil axis.

Abstract: In the representative embodiments of the present invention described herein, a new and improved directional drilling tool carrying a rotable drilling bit is dependently coupled to a rotatable drill string for excavating a borehole along one or more selected courses of excavation. Passage means on the directional drilling tool are communicated with the several fluid-discharge passages in the drill bit. A rotating flow obstructing member is arranged in the directional drilling tool for selectively communicating the drilling fluid with the bit passages as the drill bit is rotated. A selectively operable driver is arranged for rotating the flow-obstructing member at one rotational speed when it is desired to sequentially discharge drilling fluid into most, if not all, adjacent sectors of the borehole as the drill bit rotates so as to advance the drill bit along a generally linear course of excavation.

Abstract: A steering system is disclosed for percussion boring tools for boring in the earth at an angle or in a generally horizontal direction. The steering mechanism comprises a slanted-face nose member attached to the anvil of the tool to produce a turning force on the tool and movable tail fins incorporated into the trailing end of the tool which are adapted to be selectively positioned relative to the body of the tool to negate the turning force. The fins are constructed to assume a neutral position relative to the housing of the tool when the tool is allowed to turn and to assume a spin inducing position relative to the housing of the tool to cause it to rotate when the tool is to move in a straight direction. Turning force may also be imparted to the tool by an eccentric hammer which delivers an off-axis impact to the tool anvil. For straight boring, the tail fins are fixed to induce spin of the tool about its longitudinal axis to compensate for the turning effect of the slanted nose member or eccentric hammer.

Abstract: A boring head for forming a horizontal hole for a pipe installation in the subsoil beneath a roadway and the like is provided with an electrical operable guide extending forwardly from its leading end that can be selectively elevated or lowered to change the plane of forward movement of the head through the subsoil so that the location of the hole at the end of the bore can be accurately predicted. The respective movements of the guide, upwardly and downwardly, are automatically effected in response to a battery operated electronic control system designed to sense and maintain a horizontal position and to convert any sensed deviations therefrom into appropriate signals for activating and deactivating movement of the guide. The boring head is provided with a motion detecting component operably connected to the guide so that in the absence of motion in the head, the guide is rendered immobile.

Abstract: This invention relates to a process of automatic drilling with an in-hole motor particularly of the turbine type. The invention relates to apparatus and process by which the draw works responsive to a signal generated by an in-hole tachometer in the form of a train of pulses of period responsive to the rpm of the motor is sensed by a pressure transducer which generates a signal which is responsive to the rpm of the motor telemetrically in the form of the train of pulses. The signal is converted into a pressure applied to the brake of the draw works driven to hold the tension on the drilling lines and thus holds the rpm of the motor substantially consistant. In the best mode disclosed, this is accomplished by producing an electrical signal responsive to the train of pulses and storing said signal between pulses and generating a pneumatic pressure responsive to the stored signal and applying a force to said driver responsive to said last named pressure.

Abstract: An apparatus operable on a wireline logging cable for drilling a hole in the sidewall of a drill hole which comprises a hydraulically operated backup shoe for wedging the apparatus at a selected location in the drill hole, a hydraulic motor with a drilling bit connected thereto for rotation by the hydraulic motor and hydraulic means connected to the hydraulic motor for moving the bit into drilling engagement with the sidewall of the drill hole. In the improvement of this invention, the hydraulic means for moving the bit into drilling engagement comprises a new flow restrictor valve. This flow restrictor valve has an orifice and a slender pointed rod for restricting the flow of fluid through the orifice. Opposing spring means and control fluid means engage the rod for controlling its movement toward and away from the orifice.

Abstract: A fluid pressure actuated by-pass and relief valve are positioned between a source of fluid under pressure and the hollow interior of a rotor in a fluid pressure actuated downhole drilling motor. The valve includes a hollow mandrel with an inlet opening at one end and an outlet opening at the other end connected to the rotor interior and slidably received in a movable sleeve. Fluid pressure at a first predetermined value moves the mandrel into the sleeve to block the inlet opening such that the fluid by-passes the valve and flows between the stator and the rotor to rotate a bit. Fluid pressure at a higher second predetermined value moves the sleeve relative to the mandrel to expose the inlet opening and relieve the fluid pressure on the rotor and the stator. The movement of the sleeve exposes a greater surface area thereof to the fluid pressure such that a spring moves the sleeve back to block the inlet opening only at an intermediate third predetermined fluid pressure value.

Abstract: A downhole weight control device is described for connecting to the upper end of a downhole, pneumatically-operated, impact rock drilling tool for applying a downward force on the tool sufficient to maintain the drill bit in the closed working position. The weight control device has a piston member that has an effective area related to the surface area of the hammer piston in the drilling tool to effectively counterbalance an upward force of the tool tending to lift the tool. The control device also prevents exerting excessive weight on the drill bit. The control device has means for automatically decreasing the working pressure should the drill string be fed for a period of time at a rate greater than the penetration rate of the tool.

Abstract: The winning tool carried for universal movement by the frame of a tunneling machine is controlled by a system and method to limit tool movement in a manner to form a tunnel with a desired cross section. Positioning of the winning tool is determined in relation to a laser beam projecting along the length of the tunnel while the range of universal movement by the winning tool is limited by a set of tool coordinate values determined by scanning a pattern, template or the like defining an outline that is geometrically similar to the desired cross section of the tunnel. The tunneling machine carries a receiver for the laser beam that irradiates front and rear detectors each including an array of photodetectors. Servomotors respond to an output signal from the front detector to align the receiver by a translating motion so that the laser beam passes through a single passageway in the front detector to irradiate the rear detector.

Abstract: The device disclosed includes a housing which can be moved through the bore hole and anchored in the desired location for drilling a lateral hole. Located in the housing is a drill string guide or conductor having a bendable lower end. The conductor is movable to a position where its lower end is either inherently or forceably bent so that it provides a curved path leading toward the side wall of the bore hole. The conductor guides a drill string extending through the conductor to cause the drill string to drill a lateral hole in the side wall of the well bore. The drill string and conductor can be retracted into the housing when the lateral hole has been drilled, or a portion of the drill string may be left in the lateral hole as a drain pipe.