A 3D forward stratigraphic model of aeolian dune evolution for prediction of lithofacies heterogeneity

Abstract

Within aeolian systems, complex dune morphologies can develop due to the interplay of a variety of allogenic and autogenic controls. As a result, the preserved sedimentary record of aeolian dune deposits is highly varied, exhibiting an array of sedimentary architectures and facies heterogeneities. However, reconstructions of such aeolian sedimentary architectures are usually based on limited information from one-dimensional borehole data or two-dimensional outcropping successions; as such, it is challenging to predict three-dimensional architectures and the distribution of small-scale facies heterogeneities of aeolian sedimentary successions. To address this, a novel rule-based forward stratigraphic model, the Dune Architecture and Sediment Heterogeneity model (DASH), has been developed to reproduce three-dimensional sedimentary bodies, bounding surfaces and associated facies distributions formed by a wide range of dune morphologies and morphodynamic behaviours. The model generates architectural frameworks produced by dune and interdune migration and aggradation, based on a long-established modelling approach; it then applies a series of rules that reflect geological understanding or observations from geological analogues to populate the three-dimensional space with facies domains. The model has been applied to simulate the stratal architectures and facies organization of (i) three idealized examples of successions produced by different dune morphologies, and (ii) a real-world case example from the Triassic Helsby Sandstone Formation, Cheshire Basin, UK. The results demonstrate how the model can be used to predict likely facies distributions in three dimensions, which themselves can be used to constrain models of petrophysical properties constructed with geostatistical techniques. The model can therefore be applied to assist reconstructions of subsurface architectures and petrophysical heterogeneity.