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Deepwater turbidite reservoirs are a key component to BP’s resource portfolio. The use of detailed field-scale biostratigraphy in conjunction with a broader, regional scale field interpretation can significantly improve our understanding of the depositional history of these turbidite systems. The Miocene reservoir of interest is a 100-150’ thick sand with good hydrocarbon production. Calcareous nannofossils and foraminifera are initially employed within the wells to provide the general chronostratigraphic framework, in addition to identifying and classifying the major maximum flooding surfaces in the area. These wells are then correlated on a field-scale using seismic horizons, well log data, and biostratigraphic interpretations. Palynomorph assemblages allow for further details to be extracted from this distinct sand-prone interval, thus potentially minimizing geological uncertainties in the quality, connectivity, and source ‘provenance’ of the Miocene reservoir. Initial palynological analysis noted differences in the overall palynomorph assemblages from penetrations in the southwest area of the structure compared to the northeast, most notably the absence of estuarine-dominated dinocyst taxa towards the southwest. More recent well penetrations noted variability in both the presence and thickness of these stacked ‘palynofacies’ packages within the Miocene reservoir sand, suggesting a change in sediment source during/after deposition. Additionally, the distinctive ‘estuarine’ palynofacies is noted within the shale above the Miocene reservoir sand at the southernmost extent of the field suggesting diachronous deposition. Fuzzy c-means clustering (FCC) was employed to further establish the degree of mixing documented within the stacked packages. These variations suggest at least two depositional scenarios: 1) separate turbidite sand sources contributed to the Atlantis field at time of deposition and/or 2) sand deposition diachroneity.

palynofacies