Characteristics of coal-measure source rock and gas accumulation belts in marine-continental transitional facies fault basins: A case study of the Oligocene deposits in the Qiongdongnan Basin located in the northern region of the South China Sea

Abstract

This study carried out the development and distribution prediction research on coal-formed gas accumulation belts from the perspectives of the development and distribution of the coal measure source rock and the thermal evolution degrees of those rock masses in marine-continental transitional facies fault basins. The purpose of the current study was to improve the accuracy of gas reservoir explorations in the sea areas. The methods used in this study were based on the systematic analyses of the drilling, logging, geochemistry, and seismic data of the Oligocene deposits in the Qiongdongnan Basin of the northern region of the South China Sea. It had been previously established that the sedimentary processes of the fault basin were mainly controlled by faulting, and (fan) deltas had often developed in the fault bending sections, tectonic transformation sections, and fault ends. The distribution along the fault zone was observed to be beaded.

Organic geochemistry and petrology of the coals in the Laisong Formation, Naga Schuppen Belt, NE India: Inferences on hydrocarbon potential and depositional environment

“…The vitrinite reflectance of the Pinghu coals (0.55-1.28%) is also much higher than the Laisong coal, owing to deeper depth of burial and steeper geothermal gradient in the Xihu Sag (Liu et al, 2020) (Kang et al, 2020). The coal measure of the Oligocene Yacheng Formation is the most important source rock sequence in the Qiongdongnan Basin in the South China Sea region that had entered a phase of mass gas generation, owing to its high degree of thermal evolution and subsidence (Gongcheng et al, 2019).…”

Characteristics and Genesis of Biomarker Assemblages of Mesozoic Coal Measure Source Rocks in the Kuqa Depression, Tarim Basin, China

“…Coal measure source rock is an important part of gas yield and petroliferous source rock; it can be formed in various types of basins, and it is widely developed around the world. The mechanism and distribution laws governing coal measure source rock formation have been the subject of extensive inquiry [1][2][3][4][5][6][7][8]. Coal measure source rock has been used as a potential source rock for many years; M Lutz found that coal measure source rock from the Carboniferous could be a source for the large-scale generation of methane, and the same gas pool has been found in northwest Europe's southern Permian coal measure source rock [9,10].…”

“…According to the research, coal measure source rock could even have a special type of "self-generation and self-storage" capacity according to a geochemical characteristic comparison [11][12][13][14]. With the help of further research, coal-formed gas has increasingly been found in various basins [7,15,16] and by researchers who are simultaneously working on the factors that limit the petroleum potential of coal measure source rock [5,[17][18][19][20]. However, coal seams are not only warm beds of gas but also a source of oil.…”