NATURAL GAS GEOCHEMISTRY CHARACTERS AND ORIGIN OF LARGE GAS FIELD IN MARINE CARBONATES OF THE SICHUAN BASIN
四川盆地海相碳酸盐岩大型气田天然气地球化学特征与气源

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 Wo-longhe gas field should be the underlying coal measures in the Upper Permian Longtan Formation. The gas of Carboniferous in easten 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.