Sercel Inc.

Pierre Baliguet

Christophe L'Her

Loring Chien

Patrick Cook

Christophe L'her

A method and apparatus are provided for estimating the water speed of a first acoustic node D belonging to a network of acoustic nodes, at least some of the acoustic nodes being arranged along towed acoustic linear antennas (S). The method includes steps of: a) defining a N-dimensional base, the center of which is the first acoustic node and comprising a single axis, when N=1, or N non-collinear axes, when N=2 or N=3, each axis being associated with a base vector extending from the first acoustic node to another acoustic node; and b) estimating an amplitude of the water speed, as a function of: for each given other acoustic node defining the base vector: an acoustic propagation duration of an acoustic signal transmitted from the first acoustic node to the given other acoustic node, and an acoustic propagation duration of an acoustic signal transmitted from the given other acoustic nodes to the first acoustic node; and a value c of the underwater acoustic sound velocity.

Method for estimating the water speed of an acoustic node

A seismic data acquisition unit includes a data acquisition and digital circuit which receives an analog seismic signal and digitizes the signal. The digitized seismic data uses data telemetry and a repeater device to receive the compressed data and transmit the compressed data to a seismic central control unit. The data decompressor takes the data from the data compressor and decompresses the data. The decompressed data is then compared with the original digitized data to determine the amount of noise resulting from the compression process. The compression noise is compared to the ambient noise, and if the compression noise exceeds a predefined criterion, then the compression ratio in the data compressor is adjusted for a lower degree of compression. The process is repeated until the amount of compression noise, relative to ambient noise, is satisfactory.

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Nantes, France

Pierre Baliguet