2019 AAPG Annual Convention and Exhibition:

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Probabilistic Assessment of Sand Presence in Continental Rift Settings

Abstract

The interaction of climate, sediment routing, and tectonism controls the distribution and continuity of depositional environments, but these relationships are nonlinear and complex. Conceptual stratigraphic models provide useful insight into facies distribution but are typically qualitative and may not capture the full range of geologically plausible scenarios generated by these interactions. Here, we use a deterministic, nonlinear, diffusion-based forward stratigraphic model of a typical continental rift setting to demonstrate that: 1) key tectonostratigraphic processes are well-represented in the model and 2) model results can be applied to exploration risk assessment when used in a probabilistic manner. This sediment transport model acts upon a simple elastic tectonic model that approximates appropriate distributions of subsidence and uplift associated with a schematic fault architecture typical of early stage continental rifting. The model is subjected to a series of base-level, sediment supply, and water discharge scenarios, and the results of the ensemble of model realizations are synthesized into a sand presence probability map. These maps can then be used to high-grade specific areas and/or timeframes for more focused exploration. This simple sensitivity analysis can be used to better characterize facies distribution and quantify uncertainties associated geologically complex basins.