关键词: 四川盆地, 上三叠统, 陆相, 轻烃, 庚烷值, 异庚烷值, 油气生成

Abstract: The source rock drilling cuttings from Xu⁵ to Xu¹(2530~3780m)of Upper Triassic were continuously sampled in West Sichuan Basin.The absorbed hydrocarbons in the cuttings were analyzed and studied.The generation and evolution of C₄~C₇ light hydrocarbons derived from terrestrial organic matter in this area were defined as three stages:cycloalkane,alkane and aromatic.The thermal evolution triangle of light hydrocarbons from a large number of experimental data became the important foundation for the correlation of C₄~C₇ light hydrocarbons between terrestrial condensates and terrestral source rocks,as well as the correlation among terrestrial condensates from different reservoirs(different maturity)in the same structure.The modification to Thompson's maturation indexes of condensates was suggested from the discovering of the reversion of heptane and isoheptane values with R_o reaching 1.18%,not increasing with maturity in the profile section.Besides,the hydrocarbon generation model of the terrestrial organic matter in West Sichuan Basin was established based on the light hydrocarbon generation stages and the geological characteristics:gas-cycloalkane condensate stage(R_o=0.55%~1.13%),gas-alkane condensate stage (R_o=1.08%~1.40%)and gas-aromatic condensate or dry gas stage (R_o=1.30%~1.40%).

Key words: Sichuan Basin, Upper Triassic, terrestrial, light hydrocarbon, heptane value, isoheptane value, hydrocarbon generation