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Abstract: Seismic Detection of Juvenile Reservoir Character Under Fluid Cushions (Including Mobile Salt and Geopressuring)

N. S. Neidell, R. P. Mullin, M. Smith

Surface layers which can flow or release pressure via fluid leakage, and which support overburden in the subsurface most often represent difficult drilling. The incentive for penetrating such formations is typically high quality reservoirs which lie below them.

We now begin to understand that if the fluid layer can move laterally or "leak" they effectively "shield" deeper units from some measure of the overburden induced compaction process. Of course, we know from the higher conductivity of the fluid layer and temperature profile that thermal maturation of source rocks below this fluid zone would be retarded as well. Hence we can anticipate that target reservoirs may exhibit juvenile reservoir character relative to their actual geologic age and depth.

We may wish to use both well logs as well as seismic data in attempts to develop a method to detect such enhanced reservoir condition in advance of the drill. Emphasis here will focus on this measurement procedure rather than on the physics and mechanics of the flow and deformation process involved. Clearly these are worthy of study as well, but in our view at some later date.

AAPG Search and Discovery Article #90951©1996 AAPG International Conference and Exhibition, Caracas, Venezuela