详细阐述了四川盆地海相碳酸盐岩大型气田天然气的地球化学特征,包括天然气的组成、碳同位素、凝析油的轻烃和储层沥青的生物标志化合物分布特征。认为该盆地海相碳酸盐岩三个大型气田中的天然气都不是碳酸盐岩自生的,而是来源于位于其上或其下的烃源岩,其中威远气田震旦系天然气主要来自下寒武统泥质烃源岩,卧龙河气田嘉陵江组天然气主要来自上二叠统煤系烃源岩,川东石炭系天然气主要来自志留系泥质烃源岩。

Natural gas geochemistry characters of large gas field in marine carbonates of the Sichuan Basin has detailedly been expounded in this paper, According to the results of the component of the natural gas, carbon isotopes, light hydrocarbon of condensate and distribution characters of biomarkers, the gas sources of 3 large gas fields in marine carbonates of the Sichuan basin are all foreign instead of in situ. Source rocks of 1 gas fields is above the reservoir, the others are under the reservoir. The gas of  Dengying Formation in Wenyuan gas field comes from dark shale of Lower Cambrian Qiongzhusi Formation.Gas source of Jia Lingjiang Formation in Wolonghe gas field should be the underlying coal measures in the Upper Permian Longtan Formation.The gas of Carboniferous in eastern of Sichuan basin chiefly comes from dark shale of Lower Silurian.These characteristics are important significant to exploring the large gas field in the carbonates.