Computer Simulations of Shallow- and Deep-Water Depositional Systems

Tao Sun, Dachang Li, Neal L. Adair, and John C. Van Wagoner
ExxonMobil Upstream Research Company, Houston, TX

ExxonMobil has developed a process-based forward numerical model for simulation of shallow- and deep-water depositional systems. The model is fully based on the physics of fluid flow and sediment transport, and is capable of modeling physically important, but computationally challenging processes such as flow avulsion, knickpoint formation and migration, and flow channelization. Carefully measured tank experiments have also been conducted in order to compare the results with those obtained from numerical models. For jet deposits, good agreement has been found.

Physics-based forward numerical models have wide variety of applications in both stratigraphic and geologic modeling research. Here, the numerical model has been used to study the autogenic processes in the evolution of both deltaic and submarine-fan systems. Simulation results show the evolution of deltaic and submarine-fan systems follow a common pathway from jet deposits to leaf, leaf complex, and eventually to tree deposits. This pathway is also scale invariant, where similar processes are observed in all length scales within a depositional system, as well as in different systems with different sizes, suggesting a fractal distribution of sedimentary bodies in deltaic and submarine-fan systems.

Significant insights into the origin of channels in depositional systems have also been obtained. Our results suggest that avulsion and the upstream knickpoint migration cause channels to initiate and extend by intermittently adding new channel segments connecting scours of current and previous leaf deposits.