Geochemical Characteristics and Gas Source Analysis of Natural Gas from the Lower Jurassic in Northeastern Sichuan Basin

HIGHLIGHTS (1) The kerogen in the research area is predominantly Type Ⅱ, with most hydrocarbon-generating source materials derived from low organisms such as algae and plankton‌. (2) Gas component experiments and natural gas isotope analysis results indicate that the natural gas from the Lower Jurassic in the northeastern Sichuan Basin is predominantly oil-type gas, with a minor proportion exhibiting coal-type gas characteristics. (3) The enrichment of the Lower Jurassic gas reservoirs in the research area primarily relies on their own source rocks and reservoir-cap rock structures, while fractures or faults also play a significant role in areas such as Yingshan–Dazhou‌.