鄂尔多斯盆地奥陶系烃源岩支链烷烃特征及其地质意义

发布时间：2018-11-06 09:29

【摘要】：通过对鄂尔多斯盆地奥陶系马家沟组6口井烃源岩岩芯样品饱和烃的GC/MS分析,系统论述了烃源岩中支链烷烃的鉴定方法和依据,检测到碳数分布范围为C_(15)~C_(21)的中等链长的支链烷烃,主要包括2-甲基(异构)、3-甲基(反异构)、高位取代单甲基支链烷烃、双甲基支链烷烃和无环类异戊二烯烷烃;其中异构烷烃和反异构烷烃碳数分布范围较广且短、中、长链都有分布。结合研究区的沉积特征及其他有机地球化学指标,认为鄂尔多斯盆地奥陶系马家沟组中等链长的单甲基支链烷烃来源于一些特殊细菌和藻类,其中蓝细菌为最可能直接输入母质;其次一些异养细菌对原始沉积物的改造也是中等链长支链烷烃富集的重要原因之一;长链的2-甲基异构和3-甲基反异构烷烃可能与热催化重排有很大的关系。
[Abstract]:Based on the GC/MS analysis of saturated hydrocarbon in source rock core samples of 6 wells in Ordovician Majiagou formation in Ordos Basin, the identification method and basis of branched alkanes in source rocks are systematically discussed. Some branched alkanes with medium chain length in the range of C _ (15) ~ C _ (21) were detected, including 2-methyl (isomerization), 3-methyl (anti-isomerization) and high substituted monomethyl branched alkanes. Dimethyl branched alkanes and acyclic isoprene alkanes; The distribution range of carbon number of iso-alkanes and anti-iso-alkanes is relatively wide and short. Combined with the sedimentary characteristics of the study area and other organic geochemical indicators, it is considered that the monomethyl branched alkanes in the Ordovician Majiagou formation of Ordovician are derived from some special bacteria and algae. Cyanobacterium is the most likely direct input of parent material; Secondly, the modification of primary sediments by some heterotrophic bacteria is also one of the important reasons for the enrichment of alkanes with medium chain long branched alkanes, and the long chain 2-methyl-isomerization and 3-methyl-antiisomerization alkanes may be closely related to thermal catalytic rearrangement.
【作者单位】：甘肃省油气资源研究重点实验室/中国科学院油气资源研究重点实验室;中国科学院大学;
【基金】：国家重点基础研究发展计划(973计划)项目(2012CB214801) 国家科技重大专项项目(2011ZX05005-001) 甘肃省重点实验室专项(1309RTSA041)~~
【分类号】：P618.13

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