Geochemical characteristics of natural gas in the Yinggehai-Qiongdongnan Basin, South China Sea

Abstract

Geochemical characteristics of natural gas in the Yinggehai-Qiongdongnan Basin were studied and analyzed based on gas component properties and carbon isotopic characteristics which were tested and collected of more than 100 samples. The gas in the Yinggehai-Qiongdongnan Basin was generally alkane gas, and all the area showed dry gas characteristics except Yanan Depression and its periphery area. The gas in the Basin is mainly high mature -over mature coal formed gas except Songnan and eastern of the second fault belt. There are three genetic types of the natural gas in the Yinggehai-Qiongdongnan Basin, such as microbial gas, coal-formed gas and the mixture of them. The coal-formed gas is the main genetic type.