3D AVO as a Primary Tool for Reservoir Characterization in the Deep Water Gulf of Mexico

Francis O. Rollins, Charles M. Skidmore

The deep water Gulf of Mexico offers a potential resource of several billions of barrels of oil equivalent. This is an attractive target for exploration, although risky because of the high costs of deep water operation. Amoco is currently exploring in water depths exceeding 6000^prime, and 3D AVO is a key technology that will assist in both exploration and the optimization of development.

Deep water 3D AVO volumes reveal reservoir details not found on conventional slack data. The high degree of variability in lithology type and thickness in these areas can have an impact on the AVO response found in the reservoir. These changes, while present in the unstacked data, are often stacked out of the data or smeared beyond recognition in the post-stack volume. By using AVO, we have been able to identify channel and levee/overbank complexes that were not previously apparent from the stacked volume. This new information can be essential in determining the placement of future wells as well as influencing potential production scenarios.

Seismic amplitudes reflected from the highly porous and permeable sands of the deep water Gulf of Mexico often do not conform to structure. This may be due to the stratigraphic nature of deep water sands, or to seismically differentiable variations in reservoir quality. AVO responses in these areas may be more sensitive to the fluid and therefore conform to the structure present. 3D AVO can further define a prospect which was previously defined only on a stacked amplitude.

AAPG Search and Discovery Article #91020©1995 AAPG Annual Convention, Houston, Texas, May 5-8, 1995