Western Geophysical Company of America

David G Shave

Ben B Thigpen

Eldon E Crump

A seismic streamer cable, composed of a plurality of cable sections includes a common transmission line and an internally mounted inductive element in each section. The inductive elements are coupled in parallel to the common transmission line. A plurality of depth transducers, each associated with an inductive pickup, are secured externally to the streamer cable at desired intervals, adjacent to one of the internal inductive elements. A control signal is periodically transmitted through the transmission line and is received, by inductive coupling, at each transducer after a selected delay. In response to the delayed control signal, the transducers inductively launch a depth-proportional signal into the transmission line for reception by a depth readout device.

Depth transducer system for a seismic streamer cable

A survey ship proceeds along a desired track as determined by precision navigational aids. A doppler sonar is programmed to receive returns from various water masses circulating at various depths between the ship and the water bottom. The doppler sonar scans the different depths by changing the signal return-time window. The ship's track resolved with the water-current velocity components to obtain a resolved water current vector. The doppler sonar may be an integral part of the navigation system. In such a case, the doppler sonar will be commanded to lock on the water bottom at selected intervals to determine the true ship's track and at other intervals, the sonar will track one or more water masses. Alternatively, two sonar signal receivers may be used, one to continuously track the water bottom and one to scan the water masses at various depths.

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Houston, TX, United States of America

David G Shave