Characterization and quantification of Middle Miocene reservoirs of Starfak and Tiger Shoal fields, offshore Louisiana, using genetic sequence stratigraphy and neural-networks

Gulf of Mexico Outer Continental Shelf (GOM-OCS) is one of the most prolific petroleum systems in the world, but because of stratigraphic and structural complexity, Miocene reservoirs on the shelf are not efficiently drained. A new approach to partitioning and imaging of individual reservoirs is developed, and the effective porosity and volume of clay of the reservoirs were estimated in fourth-order scale sequences by neural-network analysis techniques.; In the Middle Miocene, there are 24 fourth-order (∼0.19 my) genetic sequences. These genetic sequences are defined between fourth-order maximum flooding surfaces, which are interpreted on a seismic data volume boosted to improve resolution. Spectral decomposition and balancing of seismic data allows interpretation of these fourth-order maximum-flooding surfaces, and integration of paleontological data confirms the ages and the stratigraphic order during interpretation.; Genetic sequences can be characterized in fourth-order scale by seismic facies classification and interpretation of proportionally sliced genetic sequences. While proportional amplitude slices result in a series of maps of deposition, the trace similarity yields a map of depositional elements of the genetic sequence. Interpretations of these two kinds of maps allow better understanding of reservoir architectures and complexity. A genetic sequence can be quantified in a fourth-order scale by neural-network analysis. Selected seismic attributes derived from the genetic sequences can be linked to, and used to quantify, the petrophysical character of reservoirs.; There are two orders of faults and two different kinds of opportunities in the Middle Miocene; broadly arcuate E-W trending large faults, which create large rollover structures, and N-S trending smaller faults, which create smaller structural traps. Large faults, rooted in the deep halokinetic activity across the region, form a significant topography across which thick, Early Miocene age lowstand deltas are deposited and are later deformed into large rollover structures. Smaller faults cut each other in narrow angles, and usually are cut by a large fault at a high angle. Integration of seismic, log, and production data within a fourth-order scale sequence allows identification of untapped zones, which are readily accessible for production, and bypassed small traps, developed especially among small faults, and between small and large faults.