Industry has a considerable knowledge base from the central Gulf of Mexico (GOM) slope, yet to what extent can this database provide valid analogues for other slope systems? The GOM is viewed as an end-member above-grade ponded slope system in many conceptual models. This end-member status leads to both a de-emphasis of the value of applying knowledge derived from the GOM elsewhere and the value of applying knowledge from other slope systems to the GOM. But, the GOM slope contains examples of both a) ponded reservoirs (where receiving basin topography trapped entire flow volumes transported by variable flow sizes) and b) cases where flows of variable size and volume were far less affected by confining topography and hence have potential as partial analogues for comparable (dimensions, grain size) systems in less topographically confined settings.

The Brazos-Trinity depositional system consists of four linked intraslope basins (I – IV) located on the upper slope, offshore Texas and represents a type locality for understanding general aspects of stepped above-grade slopes and specific aspects ponded above-grade slopes. Conceptual understanding of the fill history in these basins include ‘fill and spill’ models where basins fill sequentially in the seaward direction, to models which invoke coeval basin filling with the coarse fraction retained preferentially in the up-dip basins and synchronous early bypass of the fine fraction to downdip basins. Integration of recent coring results with nearly complete 3d seismic coverage has improved age dating and reconstruction of infill history. Initially flows bypassed the upper basins, forming the basal deposits in Basin IV. Deposition of high net/gross sands in Basin II resulted from stripping of muds suspended high within the flows entering the basin. These mud-prone flows exited Basin II through a tributary-like flow gathering zone near the basin exit point and ponded in the lower part of Basin IV. The upper fill in Basin IV comprises a submarine apron that is sourced by a continuous channel system directly from a lowstand delta located in Basin I. Within this apron, the observed seaward tapering is controlled by lower-efficiency sandy sediment gravity flows of relatively low volume with respect to basin size. Although high amplitude sea level fluctuations during the last glacial-interglacial cycle have modified the accumulation of sediment in Basin IV, the newly acquired data from Basins IV and II show that basin tectonics and flow dynamics also exerted a strong influence in sediment fill distribution through space and time.

The slope geometry and stratigraphic architecture for the upper fill of a typical GOM intraslope basin is similar to that observed across stepped-slope profiles documented from many continental margins including the Niger delta, NW Borneo, SE Brazil, Lower Congo and Tanzania. Because a primary control on reservoir distribution and architecture across varied slope profiles is the interaction between local gradient change and flow/grain size, analogous stratigraphic architectures may be developed at different absolute slope positions. Therefore there is potential to use the quantitative data from the GOM, after careful selection of appropriate analogues, to help constrain, a) net/gross distributions for use in STOIIP estimates from calibrated seismic facies and b) expectations of reservoir performance and reserves estimates in other basins.

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