Early Miocene sedimentary processes and their hydrocarbon implications in the Baiyun Sag of Pearl River Mouth Basin, northern south China sea

Abstract

Abstract The shelf-slope zone has received considerable attention for hydrocarbon exploration due to its unique location, where the sediments are delivered to deep-water environment and deposited as hydrocarbon reservoirs that have been discovered around the world. However, it is realized that the sedimentary processes are very complex, and various depositional bodies develop in the shelf-slope zone. Constrained by 3D seismic, core and well log data, numerical simulations can be applied to better understand the sedimentary processes, and predict the distribution and characteristics of deposits as hydrocarbon reservoirs. Based on core-log-seismic integration, the Early Miocene shelf-margin delta and channelized submarine fan systems along the northern slope of Baiyun Sag in the Pearl River Mouth Basin are distinguished and they are mainly composed of debris, turbidites and slumps. The numerical model is built based on Early Miocene topography acquired by back-stripped well-tied seismic profiles, and the initial boundary conditions, including sediment concentration, velocity and, grain size, and so on, behaviors and structures of slope system are set according to the results of marine surveys around the world. The Computational Fluid Dynamic software ANSYS-FLUENT was applied for the modelling. As a results, the distributions and geometries of the simulated deposits are compared with the depositional bodies interpreted from seismic data. The hydrodynamic simulations of the two sedimentary systems indicate that depositional bodies converge to the downstream of the slope and the basin floor, and turn tractive current into turbidity current during the sedimentary processes, which result in obviously various sedimentary characteristics in different locations. The identification of sedimentary processes in the shelf-margin delta and channelized submarine fan systems has been beneficial for predicting reservoirs and exploring hydrocarbons in the Baiyun Sag, Pearl River Mouth Basin, which is also contributing to the understanding of sedimentary process and reservoir prediction in deep-water areas around the world.