Abstract

The GA interval of the Eugene Island Block 330 field is the deposit of a late Pleistocene (approx. 0.8 Ma) shelf-margin lowstand delta complex. We integrated three-dimensional (3-D) seismic, wireline log, core, and cuttings data to examine the delta's internal architecture and to reconstruct its depositional history. This interval displays a complex vertical and lateral interfingering of channel, clinoform, and base-of-slope failure deposits over short distances (a few kilometers), and is the product of delta lobe progradation and switching accompanied by syndepositional structural development (growth faults, rollover anticline) and relative sea level change. We then integrated our sequence stratigraphic interpretation with production data. Hydrocarbon accumulations in the interval are primarily associated with the updip facies (delta mouth bar, delta front) beneath the flooding surface at the top of the interval, and not the sequence boundary at the base of the interval. Maps of seismic amplitudes associated with the top of the GA interval show patchy (mouth bar deposits) and curvilinear (interdistributary delta front) trends that indicate reservoir heterogeneities associated with depositional features. There is a good qualitative relationship between seismic amplitude and production characteristics, with the best production being from high-amplitude areas that sit high on the structure.

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