Origins and Geochemical Characteristics of Gases in LW3-1-1 Wellin the Deep Sea Region of Baiyun Sag, Pearl River Mouth Basin
珠江口盆地白云凹陷深水区LW3-1-1井天然气地球化学特征及成因探讨

The geochemical characteristics and origins of natural gases in LW3-1-1 well in deep sea region of the Baiyun sag in the Pearl River Mouth basin are studied by use of components, light hydrocarbons, stable carbon and hydrogen isotopes of the natural gases. The natural gases are pure hydrocarbon wet gases, with relatively high maturity, and generated in condensates stage. The natural gases are derived mainly from the Enping Formation and secondly from the Zhuhai Formation source rock with the Humic\|Sapropelic kerogen. The positive sequence distributions of carbon isotopes of the gases reveal that these gases are organic in origin and are from the same source. It is concluded that the sea water spreading occurred during Eocene\|Oligocene according to the relatively heavy deuterium isotopes in methane of the gases.