珠江口盆地番禺低隆起天然气成因研究

为了给白云凹陷深水区下一步油气勘探提供依据,文章运用多种天然气成因判别方法，对珠江口盆地番禺低隆起10口井38个天然气组分数据和60个稳定碳同位素数据进行了综合分析，认为该区天然气以烃类气体为主，其中甲烷含量占绝对优势，非烃气主要为N₂和CO₂，分布极不均匀；番禺低隆起的烃类气以成熟气为主，具有油型气和煤成气的混合成因特征，且以煤成气为主，其主力气源岩为白云凹陷Ⅱ₂-Ⅲ型干酪根有机质的恩平组泥岩，次要气源岩为白云凹陷Ⅰ-Ⅱ₁型干酪根有机质的文昌组泥岩；非烃气N₂和CO₂主要为无机成因。

RESEARCH ON THE ORIGIN OF NATURAL GAS IN PANYU UPLIFT IN ZHUJIANGKOU BASIN

By means of analyzing comprehensively the 38 natural gas composition and 60 stable carbon isotope data colleted from 10 wells drilled in Panyu Uplift in Zhujiangkou Basin by applying several discriminant methods of the origin of natural gas, it was considered that the natural gases in this region are mainly hydrocabon gases, the methane content being the overwhelming majority; and the non hydrocabon gases are mainly composed of N2 and CO2, their distribution being very irregular. The hydrocarbon gases are mainly mature gases and belong in the mixed gases of oil and coal formed gases, the latter cocupying a dominat position. The major gas source rocks are the Enping Formation mudstones containing Types Ⅱ2—Ⅲ kerogens in Baiyun Depression and the accessory ones the Wen chang Formation mudstones containing Types Ⅰ—Ⅱ2 kerogens in the depression. Both N2 and CO2 are inorganic genetic gases. (Financed by the projects of the National Natural Science Foundation, Nos.40238060 and 40372068)