Acoustic Well Logging Tool

摘要

1,176,293. Acoustic well-logging. MOBIL OIL CORP. 28 May, 1968 [29 May, 1967], No. 25523/68. Heading H4D. An acoustic well-logging tool 10 (Fig. 1) comprises a transceiver support 30 (Fig. 3) having a chamber 52 formed therein, a plate 54 bridging the chamber, and a transceiver 32 mounted on the plate, there being several staggered chambers 56 formed in the plate to provide intorted paths which attenuate acoustic energy travelling between transceiver 32 and support 30 so that the transceiver and support are effectively isolated from each other acoustically. Transceiver mounting.-The chambers 56 may extend partially or wholly through the plate 54 and may be filled with acoustically attenuating material, e.g. neoprene. In preferred embodiments epoxy resin bonds a lead zirconate titanate transceiver disc to metal plate 54, an aperture 60 behind the transceiver is filled with epoxy resin or natural rubber or neoprene, and chamber 52 is filled with an acoustically attenuating material (e.g. P.T.F.E. or compressed neoprene or natural rubber). Support 30 is mounted for rotation about shaft 26 in an oilfilled compartment defined by a rubber acoustic " window " 28. Well-logging.-For detecting anomalies in the wall of the well by a pulse-echo method, 1-2 MHz pulses are emitted at. a repetition rate of 2000 per second while support 30 is rotated at 100-400 r.p.m. and the logging tool is moved along the well. Angular position signals transmitted uphole control the horizontal sweep of oscilloscope 18: depth signals from measuring sheave 37 control the vertical sweep: echo signals intensity modulate the oscilloscope beam. For investigating earth formations surrounding the well the transmitted frequency is lowered to 50-100 kHz, the pulse repetition rate is 50 per second and the transceiver rotation rate is 1 r.p.m.