GEOMORPHOLOGY AND HIGH-RESOLUTION STRATIGRAPHY OF PROGRADATIONAL WAVE-DOMINATED SHORELINE DEPOSITS: IMPACT ON RESERVOIR-SCALE FACIES ARCHITECTURE

Modern and ancient progradational shoreface-shelf deposits contain a complex physical stratigraphy that is below parasequence scale. This stratigraphy is interpreted to reflect a threefold hierarchy of geomorphic elements: (1) beach ridges, approximating to units bounded by minor facies-discontinuity surfaces, (2) beach-ridge sets, bounded by surfaces across which there is a distinct offset in shoreline trajectory, and (3) progradational wave-dominated shoreline systems, which correspond to parasequences and are bounded by flooding surfaces. All three geomorphic elements and their bounding Surfaces are readily reproduced in simple process-response numerical models. A synthesis of modern and ancient datasets and numerical-modeling experiments indicates that the three geomorphic elements and associated stratigraphy can be produced by a number of mechanisms, including changes in wave climate, temporal and spatial variations in sediment Supply, and relative sea-level fluctuations. Models of high-resolution, intra-parasequence stratigraphy can be used to guide correlations in subsurface wireline-log and core datasets, thus improving the definition of reservoir facies architecture and rock-property distributions. The key to robust application of these models is the consistent identification of subtle, high-order stratigraphic surfaces, and their Subsequent correlation asshoreface-shelf clinoforms. Data from the Rannoch Formation, Brent Field, U.K. North Sea, are used to illustrate the application Of Such models, which provide a mechanism to explain anomalous fluid distributions and drainage patterns in the reservoir.