Detailed characterization of deep water gravity flow sedimentation model and sandbody configuration in eastern South China Sea

The deep water gravity flow deposits in the eastern South China Sea contain abundant oil and gas resources. Understanding the sedimentation model and sandbody configuration can guide the efficient oil and gas development. Taking A gas field in the northeast of Baiyun Depression as an example, based on coring, logging and high-resolution seismic data, the sedimentary types and evolution models of gravity flow are defined, the sand body configuration characterization and superposition pattern analysis are completed. The research shows there are four kinds of gravity flow sedimentary microfacies in A gas field: sliding-slumping, unconfined channels, overbank and channelized lobes. ZJ7 is dominated by channelized lobe deposits, and ZJ6 is dominated by sliding-slumping deposits and multi-phase water channel-overbank deposits. The thickness of the single channel is about 16m-31m, the width is about 280 m-330 m, the thickness of the single lobe is about 16 m-22 m, the width is about 400 m-650 m. The sand body superposition patterns are classified as discrete, superimposed and cut superimposed types, and the superposition direction is mainly horizontal, in which superimposed channels and lobes constitute the dominant reservoir. A three-dimensional fine geological configuration model controlled by sedimentary facies and channel -lobe nesting was established, providing support for the fine development of oil and gas.