Abstract The average total organic carbon (TOC) content of Chang 91 source rocks is 4.85%, and the main kerogen type is II1, and the average pyrolysis peak temperature is 452 °C in Zhidan-Ansai area, Ordos Basin. These show that Chang 91 source rocks have reached good to excellent level and peak hydrocarbon generation stage. Chang 91 source rocks were formed in semi-deep lacustrine sedimentary environments of fresh-brackish water and weak oxidation-reduction. The discovery of Chang 91 source rock extends the oil exploration field of Yanchang Formation, especially in Zhidan area, it is a favorable area for further exploration in Chang 9 reservoir.

中文翻译：

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鄂尔多斯盆地志丹-安塞地区上三叠统延长组长91烃源岩地球化学特征及致密油勘探意义

摘要 鄂尔多斯盆地志丹-安塞地区长91烃源岩平均总有机碳（TOC）含量为4.85%，主要干酪根类型为II1，平均热解峰温度为452℃。表明长91烃源岩已达到良好至优良水平和生烃高峰期。长91烃源岩形成于半深湖湖相的淡水-微咸水和弱氧化还原沉积环境。长91烃源岩的发现拓展了延长组油气勘探领域，尤其是志丹地区，是长9油藏进一步勘探的有利区域。