鄂尔多斯盆地西南部长8段砂岩沥青地球化学特征及其来源分析

发布时间：2018-04-24 12:56

  本文选题：鄂尔多斯盆地 + 延长组段　； 参考：《海相油气地质》2017年02期

【摘要】：系统采集了鄂尔多斯盆地西南部地区延长组8段沥青砂岩,对砂岩沥青的地球化学特征进行了研究,探讨了沥青的母质特征、形成环境和成熟度。研究结果表明:(1)长8段砂岩沥青中高碳数的正构烷烃优势明显,规则甾烷中C_(29)含量相对较高,萜烷系列中四环萜烷含量较高,C_(24)四环萜烷/(C_(24)四环萜烷+C_(26)三环萜烷)的值为0.26~0.52,C_(23)三环萜烷/(C_(23)三环萜烷+C_(30)藿烷)的值分布范围为0.06~0.41,这些都指示研究区长8段砂岩沥青母质来源为混合型,并且陆源有机质贡献较大;(2)砂岩沥青中Pr/Ph为0.67~1.07,同时,沥青中检测出低丰度的β胡萝卜烷,说明沥青形成环境为弱氧化—弱还原环境,较低丰度的伽马蜡烷与C_(30)+藿烷指示沥青的母质形成于淡水或微咸水湖泊环境;(3)长8段砂岩沥青的C31藿烷22S/(22S+22R)、C_(29)甾烷20S/(20S+20R)、C_(29)甾烷ββ/(αα+ββ)和C_(29)重排甾烷20S/(20S+20R)均接近或已经达到平衡值,反映沥青为成熟沥青。将研究结果与已报道潜在烃源岩的生物标志化合物特征进行对比,显示出研究区长8段砂岩沥青主要来源于延长组7段烃源岩,表明长7段烃源岩是研究区最主要的烃源岩之一。
[Abstract]:The 8 member bituminous sandstone of Yanchang formation in southwestern Ordos Basin is collected systematically. The geochemical characteristics of sandstone bitumen are studied and the parent material characteristics of bitumen are discussed and the forming environment and maturity are discussed. The results show that the n-alkanes with high carbon number in 8 member sandstone bitumen have obvious superiority, and C _ S _ (29) in regular steranes is relatively high. Higher content of tetracyclic terpenes in the terpene series (CST24) Tetracyclic terpene / hackenane (C26) tricyclic terpene)) the value of the terpene series is 0.260.52% C23C)) the distribution range of the tricyclic terpene C _ (30) is 0.066 ~ (0.41), which indicates that the sandstone leachate of the Chang 8 member of the study area is located in the Chang 8 member of the study area. The distribution range of the value of the terpene is 0.066 ~ (0.41), indicating that the sandstones of the Chang 8 member of the study area are leachate. The source of green parent material is mixed type. The Pr/Ph in sandstone asphalt is 0.671.07, and 尾 -daucothane with low abundance is detected in the asphalt, which indicates that the bitumen formation environment is weak oxidation-weak reduction environment. The lower abundance gamma-waxane and Cash-30) hopane indicate that the bitumen parent material was formed in the freshwater or brackish water lake environment / 3) the C31 cariane 22S/(22S 22R ~ + C ~ (29) sterane 20S/(20S _ (20R / C ~ + C ~ + C ~ (29)) sterane 尾 -beta (伪 伪 尾 尾 and C _ (29)) rearranged sterane 20S/(20S _ (20R) are close to or have reached the equilibrium value, and the rearrangement of sterane 尾 尾 (伪 伪 尾 尾) and C _ (29) sterane 20S/(20S _ (20R) are close to or have reached the equilibrium value. Reflects the asphalt as a mature asphalt. Comparing the results with the biomarker characteristics of the reported potential source rocks, it is shown that the sandstone bitumen of the Chang 8 formation is mainly derived from the source rocks of the 7th member of the Yanchang formation. It shows that the source rock of Chang 7 member is one of the most important source rocks in the study area.
【作者单位】： 中国石油化工股份有限公司江汉油田分公司;中国科学院地质与地球物理研究所兰州油气资源研究中心/中国科学院油气资源研究重点实验室;中国科学院大学;长江大学湖北省非常规油气协同创新研究中心;
【分类号】：P618.13
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