鄂尔多斯盆地南部张家滩油页岩生烃演化特征

Hydrocarbon generation and evolution characteristics of Triassic Zhangjiatan oil shale in southern Ordos Basin

  • 摘要: 鄂尔多斯盆地南部上三叠统延长组张家滩油页岩不仅是重要的固体矿产资源,也是该盆地三叠系油气的主力烃源岩。对张家滩油页岩典型露头剖面、钻井岩心进行有机碳含量(TOC)、氯仿沥青“A”及族组分、含油率等相关测试分析表明,张家滩油页岩有机质丰度高,TOC介于5.11%~36.47%,平均16.15%,生烃潜量(S0+S1+S2)介于16.58~230.98 mg/g,平均94.20 mg/g,氯仿沥青“A”介于0.42%~2.22%之间,平均1.25%,属于生烃条件极好的优质烃源岩;含油率高,介于3.52%~14.6%之间,平均8.16%,属于中高品质的油页岩;干酪根类型以Ⅰ—Ⅱ1型为主,Ro介于0.43%~1.09%。综合利用野外露头剖面和钻井岩心样品,建立了盆地南部张家滩油页岩的热演化剖面,分析了氯仿抽提前、后油页岩的含油率变化及油页岩热演化过程中含油率、热解烃产物的变化特征,揭示鄂尔多斯盆地南部张家滩油页岩具有聚集油页岩、页岩油两类资源的潜力,提出了相应的勘探开发对策。

     

    Abstract: The Zhangjiatan oil shale from the Upper Triassic Yanchang Formation in the southern Ordos Basin is an important solid mineral resource, it can also be considered as the main source rock of Triassic oil and gas in the basin. Results of analytical experiments such as TOC, bitumen extraction and group composition, oil content etc. of shale samples from key typical outcrop sections and drilling cores showed that the Zhangjiatan oil shale has a high organic matter abundance. The TOC content ranges 5.11% to 36.47%, with an average value of 16.15%. The S0+S1+S2 value distributes between 16.58-230.98 mg/g, with an average value of 94.20 mg/g. The extracted bitumen abundance is between 0.42%-2.22%, with an average value of 1.25%. Based on these analytical results, Zhangjiatan oil shale can be assigned to be high-quality source rock with an excellent hydrocarbon generation potential. The oil content of oil shale is between 3.52% and 14.6%, with an average value of 8.16%, which belongs to medium- and high-quality oil shale. The kerogen type is mainly Ⅰ-Ⅱ1, and the Ro value generally ranges from 0.43% to 1.09%. Based on field outcrop and drilling core samples, a thermal evolution profile of the Zhangjiatan oil shale in the southern Ordos Basin was established. Moreover, the oil contents of oil shale before and after solvent extraction were compared, and the variations of oil content and pyrolysis hydrocarbon products during the thermal evolution of oil shale were analyzed. There are two types of resources such as oil shale and shale oil in the Zhangjiatan oil shale with a great potential in the southern Ordos Basin. Moreover, some exploration and development countermeasures of oil shale and shale oil were put forward.

     

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