海外海上地震探査収録作業における同時船上記録処理の効用と限界

抄録

INPEX Corporation has performed six cases of onboard processing during seismic data acquisition. These were conducted in tight time schedules of contract or operations.
Another necessity of the onboard processing comes from geologist's view; hoping to perform seismic acquisition and its data analyses as same as geological surveys in front of outcrops, cuttings samples, wireline logs, etc., to look at subsurface to locate a prospect to drill timely, and to carry out simultaneous corrections and additions of survey routes and samples.
The first case was in 1994 for North Sumatra, Indonesia. It aimed at performing 2D seismic data quality control and quick-look examination of tentative location of the second wildcat drilling, which was urgently planned as a back-to-back well with the first one.
The latest one was in 2001 for Masela PSC Block, West Arafura Sea, Indonesia. The onboard processing was performed to depict 3D image of First Track Cube (700km∧2) covering the area of Abadi-1 gas discovery. INPEX was successful in this partial onboard seismic processing, and in timely depicting the main structural feature of the gas discovery. It was very much helpful in fixing the appraisal drilling location in a tight time schedule. The tight schedule was due to contractual (e. g., short period to decide PSC transfer from the first three years' period to the fourth year) and other operational constraints (e. g., limited reliable man-power).
Further progress in computer processing speed is desired to simultaneously analyze acquired seismic data onboard, and to optimize exploration and development schemes by adding or revising the survey lines and cubes. Contractual environment for seismic service-contractor should be well prepared in order not to stress them to perform their services too quickly but to well prepare, tune up all equipment and man-power for their services and be on site in time to start the survey. Too severe penalty clause could cause quick but bad services.