Akey objective of reservoir description is the early identification of reservoir compartments. Early recognition of compartments requires the integration of structural and stratigraphic data with observations of pressure and fluid contacts. At the exploration and appraisal stage of field life, static compartments may be recognized. In this talk we define static compartments as reservoir compartments defined by boundaries that, over geologic time, represent barriers to fluid flow. Within a static compartment, the contact between two fluids will settle at a single elevation. Analysis of fluid contact and pressure data was done within a rigorous framework, developed at ExxonMobil, called Reservoir Connectivity Analysis (RCA). As the field is depleted, other barriers and baffles may become apparent through observation of pressure depletion and aquifer movement. These dynamic compartments are defined by boundaries that are not effective barriers to fluid flow over geologic time, but impede flow to the extent that they have a significant impact on contact movement or pressure depletion during production.

The Genesis Oil Field is located in Green Canyon Blocks 205, 160 and 161, Gulf of Mexico.We explored the stratigraphic and structural controls on compartmentalization in two Pleistocene-age deepwater reservoirs in Genesis Field (Neb 1 and Neb 3). We interpreted the older of these reservoirs, Neb 3, as an erosionally confined channel complex. Over a geologic timescale, Neb 3 was a single compartment, with a common oil-water contact throughout the field. As the reservoir was produced, Neb 3 development wells showed a common pressure decline trend and moderate aquifer support indicating communication in the oil column and between the oil column and the aquifer. In contrast, Neb 1 showed at least two

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contacts

Top Neb 1 depth structure map showing key wells and Neb 1 oil-water contacts, fault traces and an outline of Neb 1 channel.

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