Seismic geomorphology observations of deep-water channels guiding reservoir prediction in the distal Paleogene Wilcox Formation, GoM

Abstract

Recent production successes with encouragements for the future of the Wilcox Play in deep-water GOM confirmed our 3D understanding of the main architectural elements (e.g. channels and lobes) that dominate the distal Paleogene Wilcox Formation, offshore Gulf of Mexico, USA. Seismic data analysis over most of the prospective area is challenged as the Wilcox succession is situated deep below a thick and vast salt canopy; hence, our reservoir models primarily relied on well-data, conceptual models and analogous datasets. Some sub-salt areas, and several areas outside the salt canopy offer seismic geomorphology observation and interpretation opportunities. Through detailed interpretation of seismic datasets, numerous channel segments from the distal Wilcox Fm. have been visualized and characterized. The results allowed for dimensions, sediment distribution patterns and influence of evolving substrate relief (associated with salt dynamics) on channel directions to be analysed. Seismic geomorphology patterns related to channels show significant variability in sinuosity, bifurcation, and sediment dispersal directions through time. Lobe geometries are hard to characterize from seismic datasets, hence recognition and mapping of channels in the distal basin floor fans of the Wilcox Fm. offers guidance to prediction and calibration of lobe orientation at local to semi-regional scale. Closely spaced wells allow for detailed correlation of sheet-like sub units (interpreted as lobes) and suggest a distal basin-floor setting with a relatively flat seascape during Palaeogene time with large-scale compensational stacking of units. Conventional core data from wells have also provided sedimentological evidence for channelized facies, corresponding to channel-form seismic geomorphology. The observed channels have relatively consistent widths which together with the long correlation lengths and uniform thickness of lobes point towards an organized, repeated pattern in the build-up of the distal Wilcox Formation fans. Positive production experience from these relatively low-permeability reservoirs was aided by recent improvements and implementation of advanced completion technologies. More work on reservoir characterisation and optimized development strategies is being done to maintain encouraging flow rates and ensure continuous growth of the Wilcox Play albeit on-going industrial economic challenges.

AAPG Datapages/Search and Discovery Article #90291 ©2017 AAPG Annual Convention and Exhibition, Houston, Texas, April 2-5, 2017