4D Seismic Analysis of the LF-sand, El-330 Field, Offshore Louisiana

Tucker Burkhart, Andrew Hoover, Steven E. Nelson, and Peter B. Flemings

We interpret differences in amplitude maps of the 'LF' sand (Eugene Islanc Block 330, offshore Gulf of Mexico) from 3 different seismic surveys to reflect changing acoustic behavior due to drainage with time. Amplitude histograms of the extracted surfaces are log-normally distributed with different means and standard deviations. These data were filtered to have equivalent log-normal distributions. The re-scaled amplitude maps were then differenced to examine changes in amplitude behavior through time. Most zones which are interpreted to have been water swept based on production data, show an amplitude decrease with time. However, several locations in this water swept zone, shod high amplitudes with no decrease in amplitude strength with time. These zones could represent ar eas of low permeability strata which trap by-passed pay. Alternatively, these may represent bright spots due to static effects such depositional fabric, or diagenesis of the reservoir and/or overlying seal. These preserved amplitude highs are particularly pervasive adjacent to a major antithetic fault bounding the region. We are currently constructing maps of saturation, density and velocity to further constrain the temporal signals observed in the seismic reflection data.

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