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Jess B. Kozman1, Fred Hilterman2
(1) Seismic Exchange, Inc, Houston, TX
(2) Geophysical Development Corporation, Houston, TX

Abstract: AVO analysis of long offset 2d data in the western Gulf of Mexico

During early 1999, Fugro-GeoTeam, Seismic Exchange, and Geophysical Development Corporation jointly acquired more than 6000 km of long offset non-proprietary 2d seismic data in the western Gulf of Mexico. The data was acquired using a single, 9000-meter cable, 720 live traces, and 10.5 seconds of recorded data. Line locations and orientations were specifically designed to provide unique exploration data in the Miocene trend in what has been considered to be an area of little or no sand occurrence.

The data provided challenges in processing due to cable noise in shallow operating regions and the extreme sensitivity of velocity picks at the longest offsets. Migration before stack and anisotropic moveout corrections were used to generate gathers, angle stacks, and AVO attribute sections. Gathers in the vicinity of drilled sands were analyzed and showed good agreement with full elastic models generated from digitized well logs and fluid substitution data.

Preliminary evaluation of the long offset data indicates that many Miocene sand occurrences may have been missed by 2d and 3d data with maximum offsets of 5000 to 8000 meters. The AVO response of several potentially productive sands has now been shown to become detectable only at offsets greater than two times equal to depth.

AAPG Search and Discovery Article #90914©2000 AAPG Annual Convention, New Orleans, Louisiana