Ultralyd avstandsmåler

摘要

The ultrasonic stand-off gauge has a transducer mounted on the drill collar sends and receives ultrasonic pulses between the drill collar and the bore-hole wall. A reference transducer mounted on the pressure barrel within the drill collar measures the sound speed of the drilling fluid. The reference transducer transmits a pulse through the drilling fluid in the conduit. The pulse is reflected off an internal reflector mounted in the drill collar. Since the distance between the reference transducer and the reflector is known and constant, the sound speed of the drilling fluid is determined accurately. The sound speed measurements are use to calculate values of stand-off distance. The electronic circuitry also compensates for the variations of pressure and temp.