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新近的钻探和有机地球化学测试与研究,在鄂尔多斯盆地上三叠统长9油层组上段发现了一套湖相优质烃源岩,其平均TOC达5.03%,平均沥青“A”含量达0.8603%,有机母质类型——以低等水生生物为主要来源的腐泥型,并已达到了生油高峰的热演化阶段.湖相优质烃源岩发育于湖盆的局部凹陷.各项有机、无机地球化学参数反映出长91优质烃源岩形成于淡水—微咸水、弱氧化—弱还原的半深湖相沉积环境.因此,高生产力是该套优质烃源岩形成的主控因素.薄层凝灰岩、纹层状凝灰岩的沉积,以及Eu显著正异常的发现,佐证了同期可能存在与火山喷发有关的缺氧地质事件.地质事件对长91优质烃源岩的发育起着重要的作用.
In recent drilling and organic geochemical tests and studies, a series of high-quality source rocks of the lacustrine facies have been discovered in the Upper Triassic Chang 9 oil layer of the Ordos Basin with an average TOC of 5.03% and an average asphalt content of “A” 0.8603%, organic parent material type - the sapropelic type, which is the main source of lower aquatic organisms, and has reached the thermal evolution stage of peak oil production.The high-quality source rock in the lacustrine developed in the local depression of the lake basin.The organic , Inorganic geochemical parameters reflect the formation of 91 high-quality source rocks in the freshwater - brackish water, weak oxidation - weak reduction of semi-deep lacustrine depositional environment.Therefore, high productivity is the main source of formation of this set of source rock control factors The deposition of thin tuffs and lamina-like tuffs and the discovery of significant positive anomalies of Eu corroborate the possible occurrence of hypoxic geological events associated with volcanic eruptions during the same period.Geological events play an important role in the development of the Chang 91 high-quality source rock effect.