| 摘要 |
<p>Orientation means for determining the orientation of a wedging assembly relative to the dip of a borehole or for sensing borehole inclination. The orientation means comprises four gravity sensitive mercury switches which are coded as a set of position modulated pulses and amplitude modulated at a predetermined frequency. The amplitude modulated signals are transmitted by an ultrasonic transmitter using the water filled drill string as a wave guide and are received by an ultrasonic receiver at the surface. There is also disclosed a retrievable or fixed wedging assembly in which the assembly is locked in position by means of an annular locking means which engages about the wall of the borehole at the desired position.</p> |
