Accumulation model of gas hydrate in the Chaoshan depression of South China Sea, China

Abstract

The northern waters of the South China Sea are rich in natural gas hydrate resources. The source of gas is a crucial factor controlling the formation of natural gas hydrates. Gas sources that form natural gas hydrates can be related to three categories: pyrolysis genesis, biological genesis, and inorganic genesis. A series of large- and medium-sized Mesozoic and Cenozoic sedimentary basins have developed in the northern South China Sea. These basins are rich in organic matter and there are multiple sets of source rocks buried deeply, which are the main gas sources for hydrate accumulation. The Chaoshan Depression is the largest Mesozoic residual depression in the northern South China Sea. Analysis of geochemical and geological samples show that there is a significant oil and gas leakage activity on the seabed. Seismic data and drilling confirmed the existence of natural gas hydrates in Chaoshan Depression. The natural gas hydrate accumulation pattern of Chaoshan Depression is a leak- type accumulation, which has the characteristics of unique structure, abundant Mesozoic gas source, and development of faulting system.