Well-Log Seismic Sequence Biostratigraphic Analysis In The Subsalt Trend

Walter W. Wornardt

Sediments in offshore Louisiana, Gulf of Mexico, were analyzed in non-subsalt wells away from the subsalt and non subsalt sediment interface using high resolution biostratigraphy, well-logs and seismic profiles. The Maximum Flooding Surfaces and Sequence Boundaries, lowstand prograding, slope fan and basin floor fan complexes were identified using first downhole occurrence of important tops, paleobathymetry, abundance and diversity histograms well-log signatures and seismic profiles. The reservoir sands identified in the non-subsalt wells, the bottom-set turbidites, slope fan and basin floor fan complexes, could be present in the subsalt well. The paleobathymetry, stratigraphic position within the lowstand systems tract, slope fan condensed sections (sf cs) and basin floo fan condensed sections (bf cs), fauna and flora abundances were used to help identify these reservoir sands in the subsalt and non-subsalt wells. Well-Log Sequence Biostratigraphy, the identification of the Maximum Flooding Surfaces and Sequence Boundaries, lowstand prograding, slope fan and basin floor fan complexes, first occurrence downhole of important tops, sample by paleowater depth, species abundance and diversity while the well was being drilled. After logging, the systems tract surfaces were further refined on the well-log, and seismic profile and correlated with the seismic profile in non-subsalt wells previously analyzed. This methodology combined with 3-D seismic will result in a substantial reduction in risk in the subsalt trend.

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