Geochemical and stable carbon isotope composition variations of natural gases in tight sandstones from the West Sichuan Basin, China

Recent exploration has revealed the great potential of gas resources, complicated gas distributions and geochemical characteristics of natural gases in tight sandstones of the West Sichuan Basin, China (WSBC). The chemical, stable carbon and light hydrocarbon compositions of natural gases from WSBC were investigated to assess the genesis, sources, and migration pattern leading to variations in the geochemical and stable carbon isotope compositions. The analysis shows that the natural gas in the Jurassic tight sandstones occurs as dry gas or wet gas in some places; however, most of the gas in the deep Triassic tight sandstones is apparently dry gas. Carbon isotope distributions increased in the order δ13C1