Abstract: A drill hole logging system (5) incorporates a computing system (58) at the surface and a deployment mechanism (40) for conveying a logging tool (10) configured to measure one or more geophysical parameters into a drill hole (20). A transmission means (57) communicates commands and data representing the geophysical parameters between the surface computing system and the logging tool. A borehole caliper (300) is employed to profile the inside of the borehole.

Abstract: A magnetic susceptibility and conductivity tool (10) which incorporates a transmitter coil (4) energized with a time-varying current from a transmitter coil drive (13). The transmitter coil drive receives a clock signal and induces a data signal (99) including a primary mutual coupling signal and a formation coupling signal. A receiver coil (1) outputs a receiver coil voltage induced by the data signal. A transmitter coil current sense circuit (15) receives current from the transmitter coil and outputs a digital coil current voltage signal. A synthetic null circuit (14) receives the digital current voltage signal and multiplies the digital current voltage signal with a predetermined constant (28) for amplitude of a base primary mutual coupling signal and shifts phase with a predetermined phase offset (27) to output a synthetic null signal (104).

Abstract: A magnetic susceptibility and conductivity tool (10) which incorporates a transmitter coil (4) energized with a time-varying current from a transmitter coil drive (13). The transmitter coil drive receives a clock signal and induces a data signal (99) including a primary mutual coupling signal and a formation coupling signal. A receiver coil (1) outputs a receiver coil voltage induced by the data signal. A transmitter coil current sense circuit (15) receives current from the transmitter coil and outputs a digital coil current voltage signal. A synthetic null circuit (14) receives the digital current voltage signal and multiplies the digital current voltage signal with a predetermined constant (28) for amplitude of a base primary mutual coupling signal and shifts phase with a predetermined phase offset (27) to output a synthetic null signal (104).

Abstract: A drill hole logging system (5) incorporates a computing system (58) at the surface and a deployment mechanism (40) for conveying a logging tool (10) configured to measure one or more geophysical parameters into a drill hole (20). A transmission means (57) communicates commands and data representing the geophysical parameters between the surface computing system and the logging tool. A borehole caliper (300) is employed to profile the inside of the borehole.