A method for obtaining accuracy gravity coefficients out of three orthogonally oriented accelerometer devices and a thermometer by computing, using a pre-programmed micro-control unit processor, temperature errors, bias error coefficients, sensitivity error coefficients, and orthogonality error coefficients during measurement while drilling operations. Particularly, the method uses voltage data values of the three orthogonally oriented accelerometers to compute said error coefficients which provides for zero-error positioning of the MWD tool during long-term downhole surveying as well as while facing high-shock, vibrations, and high temperatures.

A ranging system and method to determine a relative distance and direction of a target borehole relative to a second borehole using a ranging tool that can make ranging measurements while the ranging tool is not rotating. An array of button electrodes included in the ranging tool can be fired in a sequential fashion so as to simulate rotation of one or more button electrodes, without the ranging tool rotating. The array of button electrodes can also be fired in a sequential fashion so as to simulate rotational and/or longitudinal movement of the ranging tool.

A ranging system and method to determine a relative distance and direction of a target borehole relative to a second borehole using a ranging tool that can make ranging measurements while the ranging tool is not rotating. An array of button electrodes included in the ranging tool can be fired in a sequential fashion so as to simulate rotation of one or more button electrodes, without the ranging tool rotating. The array of button electrodes can also be fired in a sequential fashion so as to simulate rotational and/or longitudinal movement of the ranging tool.

The present invention is aimed to reduce power consumption of a measuring apparatus. A measuring apparatus according to the present invention is to be disposed in an excavation section of an underground excavator. The measuring apparatus according to the present invention includes a first measurement module, a second measurement module, and an information processor. The first measurement module includes a triaxial first accelerometer and a triaxial first magnetometer for performing highly-accurate measurement. The second measurement module includes a triaxial second accelerometer and a triaxial second magnetometer for performing measurement during excavation. The information processor controls the first measurement module and the second measurement module and obtains a position and an attitude of the excavation section based on output data of the first measurement module or the second measurement module. Further, the second accelerometer and the second magnetometer are MEMS sensors.

The present invention is aimed to reduce power consumption of a measuring apparatus. A measuring apparatus according to the present invention is to be disposed in an excavation section of an underground excavator. The measuring apparatus according to the present invention includes a first measurement module, a second measurement module, and an information processor. The first measurement module includes a triaxial first accelerometer and a triaxial first magnetometer for performing highly-accurate measurement. The second measurement module includes a triaxial second accelerometer and a triaxial second magnetometer for performing measurement during excavation. The information processor controls the first measurement module and the second measurement module and obtains a position and an attitude of the excavation section based on output data of the first measurement module or the second measurement module. Further, the second accelerometer and the second magnetometer are MEMS sensors.

A drilling system, comprising a drill string; and a ranging tool mounted on the drill string, the ranging tool comprising a magnetic sensor pair comprising a first magnetic sensor and a second magnetic sensor mounted radially opposite one another on the ranging tool, wherein each of the magnetic sensors is structured and configured to detect at least a radial component and a tangential component of a magnetic field; a rotatable assembly, comprising a motor structured and arranged to actuate rotation of the magnetic sensor pair around the drill string; and an electronics package connected to at least one of the magnetic sensor pair, and the motor, wherein the electronics package comprises a controller and a wireless telemetry device.

A drilling system, comprising a drill string; and a ranging tool mounted on the drill string, the ranging tool comprising a magnetic sensor pair comprising a first magnetic sensor and a second magnetic sensor mounted radially opposite one another on the ranging tool, wherein each of the magnetic sensors is structured and configured to detect at least a radial component and a tangential component of a magnetic field; a rotatable assembly, comprising a motor structured and arranged to actuate rotation of the magnetic sensor pair around the drill string; and an electronics package connected to at least one of the magnetic sensor pair, and the motor, wherein the electronics package comprises a controller and a wireless telemetry device.

A method for determining gravity toolface azimuth that can include rotating a logging tool about a center axis; positioning an accelerometer sensor within the logging tool at a first radial distance from the center axis; positioning an angular gyroscope sensor within the logging tool at a second radial distance from the center axis; receiving, at a controller, accelerometer sensor data from the accelerometer sensor and angular gyroscope sensor data from the angular gyroscope sensor as the logging tool rotates; determining, via the controller, a radial acceleration component of the accelerometer sensor from the accelerometer sensor data; determining, via the controller, a gain and an offset of the angular gyroscope sensor based on the radial acceleration component; and determining, via the controller, the gravity toolface azimuth of the logging tool as a function of time based on the gain, the offset, and the angular gyroscope sensor data.

A method for determining gravity toolface azimuth that can include rotating a logging tool about a center axis; positioning an accelerometer sensor within the logging tool at a first radial distance from the center axis; positioning an angular gyroscope sensor within the logging tool at a second radial distance from the center axis; receiving, at a controller, accelerometer sensor data from the accelerometer sensor and angular gyroscope sensor data from the angular gyroscope sensor as the logging tool rotates; determining, via the controller, a radial acceleration component of the accelerometer sensor from the accelerometer sensor data; determining, via the controller, a gain and an offset of the angular gyroscope sensor based on the radial acceleration component; and determining, via the controller, the gravity toolface azimuth of the logging tool as a function of time based on the gain, the offset, and the angular gyroscope sensor data.

A transmitter for inground use controls a depth signal transmit power in relation to a data signal transmit power such that one reception range of the depth signal at least approximately matches another, different reception range of the data signal. A portable device can form a system with the transmitter in which the portable device scans a plurality of frequencies within at least one low frequency depth signal range to measure the electromagnetic noise at each one of the plurality of frequencies and identify at least one of the frequencies as a potential depth frequency for the transmitter. The portable device can include a dual mode filter having a rebar mode and a normal mode filter. The depth signal frequency is dynamically positionable in relation to low frequency noise.