2019 AAPG Annual Convention and Exhibition:

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Predicting Reservoir Connectivity Within Ancient Coastal Plain Systems During Exploration, Appraisal and Development—Pitfalls and Best Practices

Abstract

Coastal plain and marginal marine depositional systems (meander belts, coastal lakes and bays) pose an exceptional challenge for earth scientists and engineers because they deposit reservoir bodies with (a) complex geometries, (b) resolve well below seismic resolution and (c) terminate via lateral facies transitions that are not always covered by wireline logs. In this presentation, we demonstrate how the combination of wireline log pattern analyses, geostatistics, and production/injection data, especially from the fine-grained fraction, significantly improves reservoir connectivity prediction and aids in upscaling of critical rock properties for static reservoir modeling. Reservoir connectivity predictions, in particular, are improved when the latest process sedimentologic advances in the (a) evolution of fluvial point bar and counter point bars (b) offshore-directed hyperpycnal sediment transport and (c) grain size partitioning during levee breach are implemented into reservoir modeling workflows. We utilize world-class analogs from the southern Gulf of Mexico and the Alberta foreland basin as well as modern coastal plain analogs in the southern United States, Canada, East Africa, and Southeast Asia. Well-resolvable units (i.e., “megabeds”) have a clear expression and are mappable with both, seismic and wireline logs. The high-fidelity correlation and interpretation of thinner, sub-seismic units, however, remains critical for geologists and production engineers, since these thin units often control hydrocarbon migration, the degree of production compartmentalization and connectivity during enhanced oil recovery.