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大量饱和烃样品的GC-MS测试资料显示,鄂尔多斯盆地延长组湖相烃源岩普遍分布17α(H)-C30重排藿烷(C30*),而烃源岩之间的C30*相对丰度却存在着显著的差异.总体特征是,发育于深湖相缺氧环境的长7优质烃源岩(油页岩)的C30*相对丰度较低,发育于浅湖-半深湖相、亚氧化环境的长6-长9暗色泥岩具有较高-高的C30*,特别是湖盆东北部志丹地区长7和长9黑色泥岩具异常高的C30*.生烃岩的岩性、有机质性质和各项指示氧化还原环境的地球化学参数的对比分析表明,环境的氧化还原性和岩性等是制约C30*相对丰度的主要因素,有机质类型和成熟度的影响可能是次要的.高-异常高的C30*指示淡水-微咸水、浅湖-半深湖相的亚氧化环境.因此,延长组湖相生烃岩,特别是长7优质烃源岩(油页岩)与长6-长91烃源岩(暗色泥岩)之间C30*相对丰度的差异性和分布规律的研究,可以为盆地中生界湖相原油的组群划分和油-源的精细对比提供重要的途径.
GC-MS data of a large number of saturated hydrocarbon samples show that the lacustrine source rocks in the Yanchang Formation of the Ordos Basin generally distribute 17α (H) -C30 rearranged hopane (C30 *), while the C30 * relative abundance But there is a significant difference.The overall feature is that the C30 * relative abundance of Chang 7 high-quality source rock (oil shale) developed in the deep-lake phase hypoxia environment is relatively low, developing in the shallow lacustrine-semi-deep lacustrine facies, The Chang 6-Chang 9 dark mudstone in the sub-oxidized environment has a higher-high C30 *, especially C30 * with unusually high Chang 7 and Chang 9 black mudstones in the Zhidan area in the northeastern lacustrine basin. The lithology, Comparative analysis of the organic matter properties and geochemical parameters of each redox environment indicates that the redox and lithology of the environment are the main factors restricting the relative abundance of C30 *, and the influence of organic matter type and maturity may be secondary . High-abnormally high C30 * indicates the sub-oxidizing environment of freshwater-brackish water, shallow lacustrine-semi-deep lacustrine facies. Therefore, the extension of the lacustrine hydrocarbon-generating rocks, especially the Chang 7 high-quality source rock (oil shale) The study on the differences and distribution of C30 * relative abundance between the Chang-Chang-91 source rocks (dark mudstone) Oil division and oil group - precise comparison source provides important way.