3-D Imaging Beneath Water-Bottom Channels in the Gippsland Basin: A Case Study

K. T. Jerry Young, William A. Schneider Jr., Becky G. Houston, Roy E. Clark Jr., and John R. Moore

Water-bottom channels in the Gippsland Basin cause nonhyperbolic moveout and time delays resulting in disrupted and distorted structural images on time sections. In 3-D processing, prestack depth migration is the ultimate processing technique for resolving nonhyperbolic moveout and producing correct depth images. But, the high cost and slow turnaround time of 3-D prestack depth migration limits its application. An alternative 3-D processing approach, consisting of prestack 3-D replacement dynamics, stacking, poststack inverse 3-D replacement dynamics, and 3-D poststack depth migration, was applied to a 3-D survey located near the shelf-slope edge of the Gippsland Basin.

Application of 3-D replacement dynamics reduced nonhyperbolic moveout caused by variable water depth and improved the quality of stacked traces. We found that the interval velocity distribution below the sea floor is largely controlled by compaction or depth below the sea floor. Poststack depth migration, with a compaction-based velocity field, removed the structural distortion beneath the channels, resulting in an accurate 3-D depth image.

AAPG Search and Discover Article #91019©1996 AAPG Convention and Exhibition 19-22 May 1996, San Diego, California