四川盆地二叠系烃源岩类型与生烃潜力

Types and hydrocarbon generation potential of the Permian source rocks in the Sichuan Basin

通过野外和岩心样品系统采集,对四川盆地二叠系烃源岩元素组成、Rock-Eval、碳同位素组成等地球化学参数分析,确立了二叠系烃源岩干酪根类型以Ⅱ型为主,局部存在Ⅰ型或Ⅲ型;利用烃源岩TOC和热解生烃参数探讨了其生烃潜力,泥岩有机碳含量一般高于灰岩,生烃潜力大。同时,对于高演化海相泥岩和灰岩生烃潜力进行了恢复,提出了高演化泥岩和灰岩生烃潜力的恢复对客观评价我国南方高演化碳酸盐岩具有一定必要性。四川盆地二叠系烃源岩热演化程度普遍高,已达到高-过成熟阶段;在早白垩世二叠系烃源岩进入生气高峰有利于后期天然气聚集成藏,为我国南方海相上组合天然气勘探提供了雄厚的物质基础。

Based on samples from outcrops and cores, we analyzed various geochemical parameters such as ele-mental component, Rock-Eval and carbon isotopes of the Permian source rocks. The kerogens of the Permian source rocks are dominated by type Ⅱ, with local occurrence of type Ⅰ and/or Ⅲ kerogens. Their hydrocarbon generation capacity is determined by the total organic carbon（TOC） and Rock-Eval parameters. In general,mudstones have a higher TOC, and greater potential for hydrocarbon generation than limestones. We restored the hydrocarbon generation potentials of marine mudstonse and limestones with high thermal maturity, which is necessary for the evaluation of the highly mature source rocks in South China. The Permian source rocks in SichuanBasin are generally of high thermal maturity at high to post mature stages. During the Early Cretaceous, the Permian source rocks entered into peak hydrocarbon generation and contributed to late gas accumulation in the upper marine assemblage in South China.