Pgs Geophysical As

Bengt Boberg

Christian Wilhelm Strand

Anders Goran Mattsson

Jon Falkenberg

Sverre Olsen

An apparatus for acquiring survey data including streamer equipment comprising a lead-in cable; and a geophysical streamer with a plurality of geophysical sensors distributed along the geophysical streamer, including a forward geophysical sensor; a depressor coupled to the streamer equipment in front of the forward geophysical sensor; a variable tension control device coupled at a back end of the geophysical streamer; and a plurality of tension control system sensors. A method for acquiring survey data including obtaining data from tension control system sensors of a geophysical streamer system; identifying an adjustment to be made to one or more tension control factors of the geophysical streamer system to reduce or control vibrational behavior of streamer equipment of the geophysical streamer system making the adjustment to the one or more tension control factors; and acquiring survey data with the geophysical streamer system.

Streamer equipment tension control

Techniques are disclosed relating to geophysical surveying. In some embodiments, an added unique fold parameter is determined for one or more bins during a survey of a geophysical formation. In some embodiments, the position of one or more elements of a survey system is adjusted based on the added unique fold. In some embodiments, a ratio of the determined added unique fold to a theoretically obtainable added unique fold is determined, and the adjustment may be based on this ratio. In some embodiments, an acceptability parameter is also considered. In some embodiments, survey elements may be steered to increase added unique fold without leaving coverage holes that violate an acceptability criterion. In some embodiments, the steering is performed automatically. In some embodiments, coverage parameters are graphically displayed to an operator.

Survey coverage parameters

A survey method includes towing one or more sources and one or more streamers behind a vessel to acquire geophysical survey data. Steering signals are determined for at least one of: the one or more sources, the one or more streamers, and the vessel. The steering signals minimize an error function having parameters that include a measure of a cross-line position error and a measure of data quality. The cross-line position error may be measured as an offset of the sources or the receivers from their desired paths, or in some embodiments as an offset between midpoints for base survey traces and subsequent survey traces. Some embodiments may employ a maximum spatial cross-correlation coefficient between a newly acquired trace and one or more base survey traces as a data quality measure, while others may employ a time shift, a phase rotation, or a normalized root mean square error. Data quality may indicate sensor noise levels.

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Singapore, Singapore

Bengt Boberg