Analysis of acidolysis hydrocarbon anomaly in the Chaoshan Depression of the Northern South China Sea and its response to reservoir properties

Abstract

Chaoshan Depression is a Mesozoic residual depression in the northeast of the South China Sea. It mainly develops two sets of Source rock, i.e., upper Triassic lower Jurassic shallow marine bathyal facies mudstone, lower Jurassic shallow marine shelf facies mudstone, upper Jurassic shallow marine reef limestone, and upper Jurassic basin floor fan sandstone, with good oil-gas exploration potential. It has gone through six tectonic evolution stages in the Mesozoic and Cenozoic, with strong uplift and denudation, developed fault structures, complex hydrocarbon accumulation conditions, and unknown hydrocarbon distribution laws. Analysing the Carbon Isotope Values of Acidolysis Hydrocarbons and Methane in Seabed Sediments through Detection δ 13C (‰) prediction of favourable oil-gas exploration zones, oil-gas traps, and types of oil-gas reservoirs is a fast and effective method for oil and gas geochemical exploration. The first detection of trace amounts of light and heavy hydrocarbon components and methane carbon isotope values in marine surface sediments at 200 stations in the Chaoshan Depression based on acidolysis δ 13C (‰), quantitative analysis of abundance and structural anomalies of light and heavy hydrocarbons using gas chromatography mass spectrometry, and quantitative analysis of carbon isotope values of light, heavy, and methane using the Kriging method δ13C (‰) plane distribution characteristics delineate two comprehensive anomaly zones for oil-gas exploration in the northeast and southwest of the Chaoshan Depression. CS depression is a petroleum depression, and DS-A structure is an oil gas structure.