Abstract: A system that controls a back reaming operation of a drilling rig is provided that includes a hoisting system that moves a drill pipe during a back reaming operation at a hoisting speed and a hoisting torque. The hoisting system comprises at least one back reaming parameter sensor for measuring a corresponding at least one back reaming parameter. An operator control unit allows an operator to input a predetermined value of the at least one back reaming parameter therein. A back reaming parameter sensor obtains the measured value of the at least one back reaming parameter. A control system monitors the at least one back reaming parameter. A braking assembly resists the hoisting torque of the drawworks system when the measured value of the at least one back reaming parameter equals the predetermined value of the at least one back reaming parameter.

Abstract: A system and method for controlling an HDD machine to move a cutting tool along an underground path in accordance with a pre-established bore plan. Cutting tool movement is detected from above-ground. During HDD machine operation, one or more control programs are accessed. Each of the control programs can cause the HDD machine to execute a sequence of pre-defined HDD machine actions. A particular control program of the one or more control programs is executed to augment movement of a drill pipe or the cutting tool.

Abstract: A method and apparatus for remotely controlling a machine. A remote operator controls a tracking device including a signal system for selectively emitting a remote enable signal. The remote enable signal is relayed to a control system for the machine. The control system is proximate to the machine and is adapted to enable at least one action of the machine upon detecting the remote enable signal. The machine is also adapted to disable the same action of the drilling machine upon detecting an absence of the remote enable signal for a predetermined number of intervals, each interval being of a preselected duration.

Abstract: A boring tool moves having a pitch orientation, a yaw orientation and a roll orientation and is steerable underground using the roll orientation. A maximum drill string curvature is established for steering. The boring tool is advanced over a path segment. An averaged roll characteristic is determined for movement of the boring tool along the path segment. A path segment pitch orientation is established based on at least one measured pitch orientation along the path segment. Using the maximum drill string curvature in combination with the averaged roll characteristic and the path segment pitch orientation, the yaw orientation is determined. The averaged roll characteristic is determined based on a series of incremental roll measurements that are spaced across the path segment. A set of coupled ordinary differential equations is used to characterize movement of the boring tool.

Abstract: A large diameter bore—in the range of 30 inches or more—is made through a geologic formation, such as the active surf zone and into the maritime zone. The drill head is provided with a mud powered motor (typically of the Moyno variety) which drives a hydraulic pump connected to a plurality of closed loop hydraulic circuits remotely controlled through electrical connection along the large diameter bore. One hydraulic circuit powers the rotating drill head; a second hydraulic circuit powers a mud and tailings evacuation pump; and a third hydraulic circuit articulates the drill head to provide direction. Mud exhausted from the mud motor is exhausted to the cutting head of the drill and evacuated along with dislodged cuttings through a pump in the drill head. The pump is individually controlled to pump at a rate, which assures a slight negative pressure in the required annulus about the drilled conduit, thus assuring that any leakage is from the surrounding soil into the annulus.

Abstract: A directional borehole drilling system employs a controllable drill bit, which includes one or more conical drilling surfaces. Instrumentation located near the bit measures present position when the bit is static, and dynamic toolface when the bit is rotating. This data is processed to determine the error between the present position and a desired trajectory, and the position of one or more of the bit's leg assemblies is automatically changed as needed to make the bit bore in the direction necessary to reduce the error. The controllable drill bit preferably comprises three leg assemblies mounted about the bit's central axis, each leg having a “toed-out” axle. In response to a command signal, a lower leg translates along the bit axis to cause it to bear more of the bit weight, thus excavating more deeply over the commanded toolface sector and causing the bit to bore in a preferred direction.

Abstract: A method of and system for directional drilling reduces the friction between the drill string and the well bore. A downhole drilling motor is connected to the surface by a drill string. The drilling motor is oriented at a selected tool face angle. The drill string is rotated at said surface location in a first direction until a first torque magnitude without changing the tool face angle. The drill string is then rotated in the opposite direction until a second torque magnitude is reached, again without changing the tool face angle. The drill string is rocked back and forth between the first and second torque magnitudes.

Abstract: A method for improving ROP and reducing hazards in drilling subterranean wells by using an acoustical system 15 to look ahead of the drill bit 14, detects and analyzes geologic features ahead of the bit 14 which may be qualified as drilling hazards 17. Detection of such hazards 17 may facilitate use of more aggressively penetrating bits 14 such as PDC bits as opposed to roller cone bits. In addition, other drilling parameters may be adjusted to improve ROP due to the ability to timely respond to identified hazards 17 before they may be detrimentally encountered by the bit 14. The acoustic system 15 may look ahead of the bit 14 by at least 100 meters, using propagated acoustic waves 19 to locate changes in acoustic impedance which may represent drilling hazards 17. In addition, bulk resistivity ahead of the bit 14 may also be measured and used to locate drilling hazards 17.

Abstract: The present invention generally provides a method for remotely controlling and/or monitoring at least one parameter of well bore equipment. In one aspect, the invention includes a method comprising the steps collecting data corresponding to the parameter with a sensor module; transmitting the collected data to an on-site universal data acquisition and control system; transmitting the data from the universal data acquisition and control system to a remote control/monitoring unit via a communication link; and transmitting control data from the control/monitoring unit back to at least the universal data acquisition and control system for modifying the operation of the well operation equipment.

Abstract: A method of and system for directional drilling reduces the friction between the drill string and the well bore. A downhole drilling motor is connected to the surface by a drill string. The drilling motor is oriented at a selected tool face angle. The drill string is rotated at said surface location in a first direction until a first torque magnitude without changing the tool face angle. The drill string is then rotated in the opposite direction until a second torque magnitude is reached, again without changing the tool face angle. The drill string is rocked back and forth between the first and second torque magnitudes.

Abstract: In a drilling system of the type comprising a rotatable drilling string, a drilling string communication system and a drilling direction control device connected with the drilling string, a method is provided for issuing one or more commands to the drilling direction control device utilizing a changeable first parameter associated with the drilling string and a changeable second parameter associated with the drilling string. The method includes providing at least one first parameter state, providing at least one first parameter event relating to the first parameter state; providing at least one second parameter state, providing at least one second parameter event relating to the second parameter state and issuing at least one command to the drilling direction control device in response to providing at least one of the first parameter event, the second parameter event, the first parameter state and the second parameter state.

Abstract: A method for optimizing drilling fluid hydraulics when drilling a well bore is disclosed. The drilling fluid is supplied by a surface pump through a drill string to a drill bit. The method has the step of adjusting the flow rate of a surface pump and a fluid pressure drop across the drill bit while drilling such that the drilling fluid hydraulics are optimized for a given drilling condition. In order for the flow through all the devices in the drill string to also be optimized, the flow through the devices is adjusted, thereby setting the pressure drop and the fluid flow rate through each device. As required for the overall system, the flow from the surface pump is increased or decreased as necessary.

Abstract: A micro tunnelling machine has a tunnelling head with a boring bit which is forced in a horizontal direction by a hydraulic thruster. The direction of the head is laser guided. The beam strikes a target in the head and a camera relays an image of the target to an operator located at the tunnel entrance. The operator adjusts the direction by admitting water and draining water from a pair of rams inside the head which move the boring bit up and down or left and right.

Abstract: A system and method provide for controlling an HDD machine to move a cutting tool along an underground path in accordance with a pre-established bore plan. Cutting tool movement is detected from above-ground. During HDD machine operation, one or more control programs are accessed. Each of the control programs can cause the HDD machine to execute a sequence of pre-defined HDD machine actions. A particular control program of the one or more control programs is executed to augment movement of a drill pipe or the cutting tool.

Abstract: In a method of regulating the feed force of a drilling device having a hydrostatic bore hole motor at the end of a linkage provided with a rotary and a feed drive, the feed of the linkage is set as a function of the pressure of the drive fluid for the bore hole motor in such a way that the liquid pressure remains in a predefined range or else remains constant. If the bore hole motor is equipped with an eccentricity for directional boring, for example with an angled housing, then, in addition or else independently of the feed control, directional deviations normally resulting from the linkage torsion can be compensated for by the eccentricity or the linkage being set to a corrected path angle.

Abstract: A steering tool for extended-reach directional drilling in three dimensions comprises a mud pulse telemetry section, a rotary section, and a flex section assembled as an integrated system in series along the length of the tool. The flex section comprises a flexible drive shaft and a deflection actuator for applying hydraulic pressure along the length of the shaft for bending the shaft when making inclination angle adjustments during steering. The rotary section comprises a rotator housing coupled to the deflection housing for rotating the deflection housing for making azimuth angle adjustments during steering. The onboard mud pulse telemetry section receives inclination and azimuth angle steering commands together with actual inclination and azimuth angle feedback signals during steering for use in controlling operation of the flex section and rotary section for steering the tool along a desired course.

Abstract: A portable mapping tool for use in a horizontal drilling system and associated methods use a boring tool configured for transmitting a locating signal. The mapping tool also includes at least one electromagnetic field detector which is configured for measuring the locating signal from a fixed position proximate to the surface of the ground in a drilling area. The mapping tool includes a housing and a transmitter arrangement supported by the housing for transmitting a setup locating signal for reception by the detector in the region for use in determining certain initial conditions at least prior to drilling. The associated methods include the step of configuring the mapping tool for transmitting a setup locating signal for reception by the detector in the region and using the received setup locating signal in determining certain initial conditions at least prior to drilling.

Abstract: An electromagnetic method and apparatus for directional drilling guidance of horizontal boreholes for the installation of pipelines and communication cables beneath rivers, highways and other obstacles is disclosed. A solenoid source, with horizontal axes, generates alternating electromagnetic fields which are measured in the borehole by a magnetometer with known orientation with respect to the direction of gravity near the drill bit. A preferred embodiment has a useable range of 150 meters from the source.

Abstract: A directional borehole drilling system employs a controllable drill bit, which includes one or more conical drilling surfaces. Instrumentation located near the bit measures present position when the bit is static, and dynamic toolface when the bit is rotating. This data is processed to determine the error between the present position and a desired trajectory, and the position of one or more of the bit's cones is automatically changed as needed to make the bit bore 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 leg with “toed-out” axle. In response to a command signal, a cone translates along the axle to cause it to bear more of the bit weight, thus excavating more deeply over the commanded toolface sector and causing the bit to bore in a preferred direction.

Abstract: A steerable reamer and method for use in horizontal directional drilling. The reamer includes a carrier frame rotatably coupled to a reaming body, a carrier frame housing slidably coupled to the carrier frame, and an hydraulic cylinder for tilting the carrier frame relative to the carrier frame housing. The reamer may also include sondes for monitoring the position and orientation of the reamer during operation or a laser guidance system for automatically steering the reamer along a pilot bore.

Abstract: A system and method for controlling a horizontal directional drilling (HDD) machine provides for manually controlling the HDD machine to perform a sequence of HDD machine actions. HDD machine parameters associated with the sequence of HDD machine actions are stored during manual control of the HDD machine. Storing of the HDD machine parameters is subsequently terminated, typically by an operator or HDD machine controller, upon completing the sequence of HDD machine actions. The stored HDD machine parameters define all or part of an executable control program associated with the sequence of HDD machine actions. The control programs may be categorized to define libraries and accessed by users. Selected categorized control programs may be transferred to a memory of the HDD machine or other storage resource for subsequent execution by the HDD machine.

Abstract: An apparatus is provided for maintaining control of a machine which produces thrust, rotation or other outputs in response to input signals. The apparatus has two distinct parts, namely the operator input portion and the output portion. The operator input portion consists of the primary thrust, rotation and other output control, and the input signal generation, signal maintenance and signal resume control. Through these controls, the operator enters the desired operation at conditions and levels for rotation, thrust, and other input signals. The output portion consists of an information processing and control portion and the power units for rotation, thrust and other outputs generated from the machine. The information processing and control system interprets all of the desired operational conditions and levels from the input portion and sends commands to the thrust, rotation and other power units to produce the desired outputs in response to the input signals.

Abstract: A radar-plow drillstring steering system comprises a steering plow and a measurements-while-drilling instrument for mounting just behind the drill bit and downhole motor of a drill rod. The instrument includes a radar system connected to upward-looking and downward-looking horn antennas and a dielectric-constant sensor. The steering plow includes four pressure pads radially distributed around the outside surface and their associated servo motors. A coordinated control of the pressure pads allows the steering plow to push the drillstring and drill bit up-down-left-right. The antennas and sensor are embedded in respective ones of the pressure pads and are used to electronically and non-invasively probe a coal seam to locate its upper and lower boundary layers. The dielectric-constant sensor provides corrective data for the up and down distance measurements. Such measurements and data are radio communicated to the surface for tomographic processing and user display.

Abstract: A downhole drilling apparatus suspended by tubing includes a drill bit driven by an electric motor powered by a cable means. The motor is mounted upon a hollow shaft which allows fluid to pass through, so that a fluid circuit along the tube and back along the annulus between the borehole and the tubing via the drill bit is established. The state of the motor, particularly its speed and torque, can be monitored, and the motor may then be regulated as a result of this data. Various sensors may be included in the drilling apparatus, and the data gathered similarly used to regulate the motor. Thrust means are included to urge the drill along the borehole. Supplementary pumps may be provided to assist the fluid flow. Both the thrust means and the pumps may be controlled by the control means.

Abstract: A method is disclosed as part of an overall process in which a boring tool is moved through the ground within a given region along a particular path in an orientation which includes pitch. A locating signal is transmitted from the boring tool which signal exhibits a field defined forward point within a reference surface which field defined forward point is vertically above an inground forward point on the particular path through which the boring tool is likely to pass. The method establishes a predicted depth of the boring tool at the inground forward point by first identifying the field defined forward point. The signal strength of the locating signal is then measured at the field defined forward point as being representative of the depth of the boring tool at an inground upstream point which is the current location of the boring tool. With the boring tool at the upstream inground point, the pitch of the boring tool is determined.

Abstract: A drilling assembly for drilling deviated wellbores includes a drill bit and a drilling motor that provides rotary power to the drill bit. A steering device integrated into drilling motor assembly contains a plurality of force application members. In one embodiment, each force application member is adapted to exert an adjustable amount of force on the wellbore interior. A separate or common power unit at or uphole of the drilling motor provides power to the force application members. A control device and control circuit can cooperate to independently operate each of the force application members. An inductive transmission device can be used to transmit electrical signals and/or power between rotating and non-rotating section of the drilling motor. During drilling of a wellbore, the force application members are operated to adjust the force on the wellbore to drill the wellbore in the desired direction.

Abstract: A down hole motor assembly includes a hydraulic drive portion, a drill bit operatively connected to the drive portion and a disengage mechanism (11) arranged to disengage drive to the drill bit. The disengage mechanism (11) is arranged to be actuated by supplying drilling fluid to the drive portion at a flow rate which is greater than the flow rate at which fluid is supplied to run the drive portion during normal drilling. The disengage mechanism is arranged to be re-set so that drive is reconnected to the drill bit when the fluid supply to the drive portion is shut off.

Abstract: The present invention provides a drilling assembly that includes a mud motor that rotates a drill bit and a set of independently expandable ribs. A stabilizer uphole of the ribs provides stability. A second set of ribs may be disposed on the drilling assembly. Vertical and curved holes are drilled by rotating the drill bit by the mud motor and by independently adjusting the rib forces. The drill string is not rotated. Inclined straight sections and curved sections may be drilled by independent adjustment of the rib forces and by rotating the drill bit with the motor, without rotating the drill string. Inclined sections or curved sections in the vertical plane are drilled by superimposing the drillstring rotation on the mud motor rotation and by setting the rib forces to the same predetermined values. Rib forces are adjusted if the drilling direction differs from the defined inclination. The system is self-adjusting and operates in a closed loop manner.

Abstract: The device provides a method for positioning the drill bit in a drilling operation to achieve small changes in hole angle or azimuth as drilling proceeds. Two different positions are available to the operator. The first is a straight ahead position where the tool essentially becomes a packed hole stabilizer assembly. The second position tilts the bit across a rotating fulcrum to give a calculated offset at the bit-formation interface. The direction that the bit offset is applied in relation to current hole direction is controlled by positioning the orienting pistons prior to each drilling cycle, through the use of current measurement-while-drilling (MWD) technology. Components of the tool comprise a MWD housing, upper steering and drive mandrel, non-rotating position housing, lower drive mandrel splined with the upper mandrel, rotating fulcrum stabilizer and drill bit.

Abstract: Between a drilling motor and the upwardly continuing drill string a housing contains a speed sensor rotationally connected to the motor rotor. Motor speed is sensed and if rotating at a rate less than a selected speed, a cooperating by-pass valve opens to shunt drilling fluid to the well annulus to prevent damage to the stalled motor.

Abstract: A guidance system for a drill tool (1) comprising a primary guidance package and a magnetic solenoid transmitter (9). The primary guidance package contains signal generator. The signal generator produces a signal indicative of the location of the drill tool 1. The magnetic solenoid transmitter both transmits the primary guidance data to a signal processor and emits an electromagnetic field. Using a locator (35), an operator can periodically determine the actual drill tool position by detecting the electromagnetic field. The actual position of the drill tool as determined by the electromagnetic field is used to correct for an integration error that is introduced into the drill tool position by the guidance technique used by the primary guidance package.

Abstract: Systems and methods for sensing at an underground drilling device in communication with an above-ground locator involve transmitting a radar probe signal from the underground drilling device. A radar return signal is received at the underground drilling device. The radar return signal is processed at the underground drilling device to produce sensor data. The sensor data is transmitted in a form suitable for reception by the above-ground locator.

Abstract: The present invention provides a method for drilling, analyzing, and stabilizing subsurface formations. The system is generally formed around a reusable bottomhole assembly (BHA) that provides an anchoring and thrust mechanism, furnishing the necessary downward force needed to provide comminution of geological material in a borehole. The BHA is conveyed into the borehole via a communications link wireline equiped with internal power and data telemetry lines. The BHA permits the use of multiple comminution sampling and analysis tools via a coupling device. The BHA and communications link wireline are mounted so as to couple with different tools. The main drilling mechanism is a torque drive assembly powered coring tool. A borehole televiewer and/or logging analysis tool may follow each coring period. The final step in each coring period is a wellbore consolidation technique. This series of steps is then repeated, each time coring the wellbore to a deeper depth.

Abstract: The present invention provides a drilling assembly that includes a mud motor that rotates a drill bit and a set of independently expandable ribs. A stabilizer uphole of the ribs provides stability. A second set of ribs may be disposed on the drilling assembly. Vertical and curved holes are drilled by rotating the drill bit by the mud motor and by independently adjusting the rib forces. The drill string is not rotated. Inclined straight sections and curved sections may be drilled by independent adjustment of the rib forces and by rotating the drill bit with the motor, without rotating the drill string. Inclined sections or curved sections in the vertical plane are drilled by superimposing the drillstring rotation on the mud motor rotation and by setting the rib forces to the same predetermined values. Rib forces are adjusted if the drilling direction differs from the defined inclination. The system is self-adjusting and operates in a closed loop manner.

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.

Abstract: An apparatus for obtaining resistivity images of a borehole having an oil-based mud includes a rotating measure electrode on a measurement-while-drilling apparatus. A modulated measure current is capacitively coupled to the formation through the non-conducting mud. The electrode may be carried on a stabilizer of the drilling assembly. An extendable arm may be used to maintain a desired distance between the electrode and the formation.

Abstract: A steering tool for extended-reach directional drilling in three dimensions comprises a mud pulse telemetry section, a rotary section, and a flex section assembled as an integrated system in series along the length of the tool. The flex section comprises a flexible drive shaft and a deflection actuator for applying hydraulic pressure along the length of the shaft for bending the shaft when making inclination angle adjustments during steering. The rotary section comprises a rotator housing coupled to the deflection housing for rotating the deflection housing for making azimuth angle adjustments during steering. The onboard mud pulse telemetry section receives inclination and azimuth angle steering commands together with actual inclination and azimuth angle feedback signals during steering for use in controlling operation of the flex section and rotary section for steering the tool along a desired course.

Abstract: An apparatus and method for determining a location and an orientation of an underground boring tool by employment of a radar-like probe and detection technique. The boring tool is provided with a device which generates a specific signature signal in response to a probe signal transmitted from above the ground. Cooperation between the probe signal transmitter at ground level and the signature signal generating device provided at the underground boring tool results in accurate detection of the boring tool location and, if desired, orientation, despite the presence of a large background signal. Precision detection of the boring tool location and orientation enables the operator to accurately locate the boring tool during operation and, if provided with a directional capacity, avoid buried obstacles such as utilities and other hazards. The signature signal produced by the boring tool may be generated either passively or actively, and may be a microwave or an acoustic signal.

Abstract: A method of and system for controlling directional drilling determines a relationship between surface drill string orientation angle and drill bit face angle. The method uses the relationship to determine a predicted drill bit face angle. The method then uses the predicted drill bit face angle to achieve a target drill bit face angle by calculating a surface drill string correction angle. The correction angle may be displayed to a human driller. Alternatively, the correction angle may be provided as an input to an automated drilling machine.

Abstract: A steerable reamer and method for use in horizontal directional drilling. The reamer includes a carrier frame rotatably coupled to a reaming body, a carrier frame housing slidably coupled to the carrier frame, and an hydraulic cylinder for tilting the carrier frame relative to the carrier frame housing. The reamer may also include sondes for monitoring the position and orientation of the reamer during operation or a laser guidance system for automatically steering the reamer along a pilot bore.

Abstract: A method of controlling rock drilling performed by a rock drill provided with a pressure-driven hammer and a rotation motor. In the method, the speed of rotation of the drill rod is defined on the basis of the value of the control signal used to control the control valve that adjusts the flow of the pressure fluid to the rotation motor.

Abstract: A portable mapping tool for use in a horizontal drilling system and associated methods use a boring tool configured for transmitting a locating signal. The mapping tool also includes at least one electromagnetic field detector which is configured for measuring the locating signal from a fixed position proximate to the surface of the ground in a drilling area. The mapping tool includes a housing and a transmitter arrangement supported by the housing for transmitting a setup locating signal for reception by the detector in the region for use in determining certain initial conditions at least prior to drilling. The associated methods include the step of configuring the mapping tool for transmitting a setup locating signal for reception by the detector in the region and using the received setup locating signal in determining certain initial conditions at least prior to drilling.

Abstract: The invention concerns a drilling system having a drilling head (2, 2′) fixed to a drill string (3) which comprises an outer pipe (12, 12′) and a percussion string (13, 13′) inserted therein, wherein the percussion string (13, 13′) comprises a plurality of rods (14, 14′) which bear against each other with their end faces (19, 20; 19′, 20′). Known systems were suitable exclusively for producing straight boreholes. One object of the present invention is to provide a drilling system with an inner percussion string, which permits a greater variation in the drilling direction and which can be used as a directional drilling system. To attain that object the outer pipe (12) is adapted to be deformable along its longitudinal axis and the end faces (19, 20) which bear against each other of two rods (14) are so designed that they bear against each other substantially in surface contact upon inclined positioning of the axes of the two rods (14) relative to each other.

Abstract: An orienter for controlling the drilling direction in a well. A main body 40, 23 is couplable to a drill string, and a nose tubing 50 is movably mounted by a universal joint in the main body. A collar 42 with a bore 43 engages in a cam-like manner with an extension 26 of the nose tubing on the drill string side of the universal joint. The collar is movable longitudinally ‘a’ to control the magnitude ‘b’ of the nose tubing, and circumferentially ‘c’ to control the azimuth ‘d’. The nose tubing is aligned on both sides of the universal joint and the bore of the collar is angled relative to the main axis of the main body. The collar may be hydraulically or electrically controlled.

Abstract: The present invention provides an improved coring motor for use in obtaining a core sample from the side wall of a drilled bore hole. The present invention provides controllable rotation, extension and retraction of the coring bit relative to the side wall without complicated positioning linkages and with conservation of space for use in slim tools for use downhole.

Abstract: An auger drill directional control system includes a positional transmitter mounted on a drillhead at the front of a pipe, the positional transmitter transmitting directional and pitch signals to a positional receiver disposed above the grade at the desired terminal location of the drillhead; the positional receiver transfers the signal information to the positional processor that detects deviations by the drillhead from the desired course of travel and produces a correction signal to compensate for the deviation; the correction signal is transmitted by a control transmitter and is received by a control receiver disposed on the underground boring machine; the control receiver passes the correction signal to the control processor which converts the correction signal into a correction command that is delivered to an adjustment apparatus operatively connected with the drillhead.

Abstract: A guidance system for a drill tool (1) comprising a primary guidance package and a magnetic solenoid transmitter (9). The primary guidance package contains signal generator. The signal generator produces a signal indicative of the location of the drill tool 1. The magnetic solenoid transmitter both transmits the primary guidance data to a signal processor and emits an electromagnetic field. Using a locator (35), an operator can periodically determine the actual drill tool position by detecting the electromagnetic field. The actual position of the drill tool as determined by the electromagnetic field is used to correct for an integration error that is introduced into the drill tool position by the guidance technique used by the primary guidance package.

Abstract: A system and method for controlling an underground boring tool involves the use of one or more of a gyroscope, accelerometer, and magnetometer sensor provided in or proximate the boring tool. The location of the boring tool is detected substantially in real-time. A controller produces a control signal substantially in real-time in response to the detected boring tool location and sensed parameters of a boring tool driving apparatus. The control signal is applied to the driving apparatus to control one or both of a rate and a direction of boring tool movement along the underground path. The gyroscope, accelerometer, and magnetometers may be of a conventional design, but are preferably of a solid-state design. Telemetry data is communicated electromagnetically, optically or capacitively between the navigation sensors at the boring tool and the controller via the drill string or an above-ground tracker unit.

Abstract: There is disclosed a locator/control arrangement for locating and controlling underground movement of a boring tool which is operated from a drill rig. An associated method is also disclosed. The boring tool includes means for emitting a locating signal. The locator/control arrangement includes a portable device for generating certain information about the position of the boring tool in response to and using the locating signal. In addition, the portable device includes means for generating command signals in view of the generated certain information and for transmitting the command signals to the drill rig. Means located at the drill rig then receives the command signals whereby the command signals can be used to control the boring tool. In one feature, the means located at the drill rig for receiving the command signals may include means for indicating the command signals to a drill rig operator.

Abstract: A torque limiting device that allows a drill string to rotate relative to the cutting structure of the bit when a predetermined torque is applied between the cutting structure of the drill bit and the drill string. The torque limiting device utilizes a retaining member which restricts rotational movement of a first component of the torque limiting device relative to a second component. When a sufficient torque load is placed on the cutting structure of the drill bit, the retaining member allows rotational movement of the first component relative to the second component and allows the drill string to continue to rotate relative to the cutting structure of the bit until the torque is sufficiently reduced. The torque limiting device may be an integral part of a drill bit, may be a separate device attached between the drill string and the drill bit or between the drill string and a downhole motor, or may be part of a near-bit sub or incorporated in a downhole motor.