Natural gas genetic types and source rocks in the northern slope of Baiyun Sag to Panyu Low Uplift in Pearl River Mouth Basin

The genetic types of natural gas and their source rock compositions were discussed in the northern slope of Baiyun Sag to Panyu Low Uplift in Pearl River Mouth Basin on the basis of former studies.According to the stable carbon isotope of methane and ethane, natural gas in the studied area can be classified into 5 main genetic types, including biogas, biothermal-catalytic gas, matured mixture coaliferous gas, matured to high-matured mixture petroliferous gas and matured to high-matured coaliferous gas. Sterane and terpane biomarkers of associated condensate oil in natural gas have two types of obviously different source compositions, which came from organic matter both enrichment-type coal and type-Ⅲ dispersed kerogen. So, hydrocarbon in the studied area was mainly generated from the matured to high-matured source rocks located in coal beds of Oligocene Enping Formation, shore-shallow lacustrine source rocks of Oligocene Enping Formation and Eocene Wenchang Formation. The further analyses of petroleum geological and geochemical characteristics show that this area has a great exploration prospect of natural gas and good potential of petroleum resource.