A boring tool is movable through the ground. A transmitter supported by the boring tool transmits an electromagnetic homing signal. A portable device monitors the electromagnetic homing signal and receives the electromagnetic homing signal in a homing mode for guiding the boring tool to a target position. A processor generates steering commands for guiding the boring tool based on a bore plan in a steering mode such that at least some positional error is introduced without using the electromagnetic homing signal. Switching from the steering mode to the homing mode is based on monitoring of the electromagnetic homing signal as the boring tool approaches the portable device to then guide the boring tool to the target position location in compensation for the positional error. Intermediate target positions are described as well as guiding the boring tool based on the homing signal so long as the portable device receives the signal.

A boring tool is movable through the ground. A transmitter supported by the boring tool transmits an electromagnetic homing signal. A portable device monitors the electromagnetic homing signal and receives the electromagnetic homing signal in a homing mode for guiding the boring tool to a target position. A processor generates steering commands for guiding the boring tool based on a bore plan in a steering mode such that at least some positional error is introduced without using the electromagnetic homing signal. Switching from the steering mode to the homing mode is based on monitoring of the electromagnetic homing signal as the boring tool approaches the portable device to then guide the boring tool to the target position location in compensation for the positional error. Intermediate target positions are described as well as guiding the boring tool based on the homing signal so long as the portable device receives the signal.

A system for tracking and guiding a downhole tool underground along a desired borepath. GPS measurements are taken by a GPS unit at desired waypoints on the ground surface that overlays the desired borepath. A planned route for the downhole tool to follow underground is generated from the GPS measurements of the waypoints. A tracker is used to track the location of the downhole tool underground while drilling a borepath. GPS measurements of a series of above-ground locations that overlay the borepath created by the moving downhole tool are taken and sent to the processor. The processor checks for deviation between the GPS measurements of the above-ground locations and the planned route and provides directions to correct the borepath of the downhole tool in response to the deviation.

A system for tracking and guiding a downhole tool underground along a desired borepath. GPS measurements are taken by a GPS unit at desired waypoints on the ground surface that overlays the desired borepath. A planned route for the downhole tool to follow underground is generated from the GPS measurements of the waypoints. A tracker is used to track the location of the downhole tool underground while drilling a borepath. GPS measurements of a series of above-ground locations that overlay the borepath created by the moving downhole tool are taken and sent to the processor. The processor checks for deviation between the GPS measurements of the above-ground locations and the planned route and provides directions to correct the borepath of the downhole tool in response to the deviation.

In an embodiment, the present system can primarily determine the pilot bore profile of a horizontal directional drill (HDD) based on the number of rod sections added and the pitch reading from the underground transmitter at the front of the drill string (as communicated to the HDD drill rig via the walk-over locator), with such calculations being able to be made at the HDD drill rig and/or related remote display on the HDD drill rig. That is, since the length of a given rod section is known and the pitch readout is provided by the underground transmitter, the change in the overall depth of the drill string can be calculated, for example, on drill rod to drill rod basis based on rise over run geometry. The walk-over locator can then be used for a secondary confirmation of the actual depth, if conditions permit (e.g., in range of a direct walk-over).

In an embodiment, the present system can primarily determine the pilot bore profile of a horizontal directional drill (HDD) based on the number of rod sections added and the pitch reading from the underground transmitter at the front of the drill string (as communicated to the HDD drill rig via the walk-over locator), with such calculations being able to be made at the HDD drill rig and/or related remote display on the HDD drill rig. That is, since the length of a given rod section is known and the pitch readout is provided by the underground transmitter, the change in the overall depth of the drill string can be calculated, for example, on drill rod to drill rod basis based on rise over run geometry. The walk-over locator can then be used for a secondary confirmation of the actual depth, if conditions permit (e.g., in range of a direct walk-over).

A device rotates at least one static magnetic field about an axis, producing a rotating magnetic dipole field, and is movable in relation to the surface of the ground. The field is periodically sensed using a receiver to produce a receiver output responsive to the field. A positional relationship between the receiver and the device is monitored using the output. In one aspect, changing the positional relationship, by moving the device nearer to a boring tool which supports the receiver, causes an increase in accuracy of depth determination. In another aspect, determination of an actual overhead position of the boring tool, and its application, are described. Use of a plurality of measurements over at least one-half revolution of each magnet is disclosed. Establishing a surface radial direction toward a boring tool and resolution of multi-valued parameters is described. Calibration techniques, as well as a three transmitter configuration are also described.

A device rotates at least one static magnetic field about an axis, producing a rotating magnetic dipole field, and is movable in relation to the surface of the ground. The field is periodically sensed using a receiver to produce a receiver output responsive to the field. A positional relationship between the receiver and the device is monitored using the output. In one aspect, changing the positional relationship, by moving the device nearer to a boring tool which supports the receiver, causes an increase in accuracy of depth determination. In another aspect, determination of an actual overhead position of the boring tool, and its application, are described. Use of a plurality of measurements over at least one-half revolution of each magnet is disclosed. Establishing a surface radial direction toward a boring tool and resolution of multi-valued parameters is described. Calibration techniques, as well as a three transmitter configuration are also described.

A boring tool that is moved by a drill string to form an underground bore. A transmitter transmits a time varying dipole field as a homing field from the boring tool. A pitch sensor detects a pitch orientation of the boring tool. A homing receiver is positionable at a target location for detecting the homing field to produce a set of flux measurements. A processing arrangement uses the pitch orientation and flux measurements with a determined length of the drill string to determine a vertical homing command for use in controlling depth in directing the boring tool to the target location such that the vertical homing command is generated with a particular accuracy at a given range between the transmitter and the homing receiver and which would otherwise be generated with the particular accuracy for a standard range, different from the particular range. An associated system and method are described.

A boring tool that is moved by a drill string to form an underground bore. A transmitter transmits a time varying dipole field as a homing field from the boring tool. A pitch sensor detects a pitch orientation of the boring tool. A homing receiver is positionable at a target location for detecting the homing field to produce a set of flux measurements. A processing arrangement uses the pitch orientation and flux measurements with a determined length of the drill string to determine a vertical homing command for use in controlling depth in directing the boring tool to the target location such that the vertical homing command is generated with a particular accuracy at a given range between the transmitter and the homing receiver and which would otherwise be generated with the particular accuracy for a standard range, different from the particular range. An associated system and method are described.