Abstract: The present invention is concerned with a system for the real time location of deep boreholes while drilling. The system includes a plurality of sensors sensitive to seismic vibrations disposed in an area where a borehole is to he drilled, the sensors being adapted to selectively pick up the vibrations emitted by the drilling bit as it progresses through the rock. The data picked up by the sensors is then processed and the results are displayed in real time, thus allowing the operator to know precisely the location of the drill bit as the hole is being drilled.

Abstract: A borehole deviation monitor comprises a probe body adapted to be lowered in a borehole and including two inclinometers mounted in an orthogonal configuration to provide simultaneous X and Y axis inclination signals indicating the dip angle of the borehole with respect to the vertical and two triaxial magnetometers to provide reference signals indicating the azimuth angle of the borehole. The magnetometers are separated by a predetermined distance along the axis of the probe. A cable takeup winch mechanism is provided to lower the probe body into the borehole by predetermined increments equal to the distance between the two magnetometers. A control and data storage station is connected to the two inclinometers and magnetometers for reading and storing the data collected at each incremental distance and for correcting the azimuth reading given by the top magnetometer by substracting any difference in readings between the two magnetometers at the previous position of the probe.