Using Differential GPS With Navigation and Data Management Systems for Conducting Ocean Bottom Cable Marine Seismic Surveys

Mohamed Abousalem, Phil Howells, Colin Acheson, Charles Mitchell, Zamtir Pop

Abstract:	Differential GPS positioning, data management and quality control are the key elements of the Seismic Management System (SMS-4000TM) and the Separation Vector System (SVS-5012TM) developed by RACAL-NCS for marine seismic operations. The SMS-4000 is used during Ocean Bottom Cable (OBC) laying operations for data management and navigation guidance in conjunction with a differential (DGPS) GPS system. During the seismic gun shooting phase which follows cable laying, the SVS-5012 is used to determine the real-time differential positions of the tail-buoys situated on the seismic gun arrays. The SMS is also used during this phase to provide shot control via management of various real-time positioning data received from the SVS system and other sensors such as rate gyros, laser ranging, gun controllers and radio telemetry. The SMS and the SVS utilize Kalman filters for position and velocity determination for the vessel and each tail- buoy. In the SVS, the UK Offshore Operators Association (UKOOA) guidelines for DGPS quality control measures are implemented with extensive textual and graphical user display. Detection and identification of measurement blunders are performed along with the computation of statistical confidence regions. Reliability measures are also computed in real-time giving a measure for the strength of the solution. Described in this paper are the various software and hardware components of the SMS and the SVS systems together with their method of operation. Description of the software features and display screens is given with indications on current and future system developments and enhancements. Also presented are some illustrative performance test results portraying the accuracy and repeatability of the integrated systems.
Published in:	Proceedings of the 1997 National Technical Meeting of The Institute of Navigation January 14 - 16, 1997 Loews Santa Monica Hotel Santa Monica, CA
Pages:	607 - 615
Cite this article:	Abousalem, Mohamed, Howells, Phil, Acheson, Colin, Mitchell, Charles, Pop, Zamtir, "Using Differential GPS With Navigation and Data Management Systems for Conducting Ocean Bottom Cable Marine Seismic Surveys," Proceedings of the 1997 National Technical Meeting of The Institute of Navigation, Santa Monica, CA, January 1997, pp. 607-615.
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