鄂尔多斯盆地盐池-定边地区长7段烃源岩芳烃地球化学特征

基于鄂尔多斯盆地盐池-定边地区13口井16块长7烃源岩样品的GC-MS分析资料，研究了源岩的芳烃地球化学特征，进行了生源和沉积环境的分析，并探讨了芳烃系列成熟度评价参数在该地区的有效性。研究结果显示:研究区源岩主要以二环和三环芳烃类化合物为主，而四环和五环芳烃类化合物较低，芴含量较高，普遍含有1，2，5-TMN和1，2，5，6-TeMN且部分样品含量偏高，并检测出一定含量的惹烯、苝、和芘等陆源高等植物生物标志化合物，表明研究区源岩形成于滨浅湖弱氧化-弱还原的环境中，高等植物的输入对该地区源岩的形成占有一定贡献。芳烃中烷基萘、烷基菲和烷基二苯并噻吩等成熟度参数表明源岩样品现今正处于成熟阶段。虽然利用不同系列芳烃类化合物求取的等效镜质体反射率存在一定差异，但能定性地反映出源岩的热演化程度。

Geochemical Characteristics of Aromatic Hydrocarbons of Chang7 Source Rocks from the Yanchi-Dingbian Area,Ordos Basin

Based on the GC-MS analytical data of 16 samples of Chang7 source rocks from 13 wells in the Yanchi-Dingbian area, Ordos Basin, the geochemical characteristics of aromatic hydrocarbons of source rocks, the origins and sedimentary environments were investigated in detail, and the validity of maturity parameters of aromatic hydrocarbon biomarkers were discussed. It is shown that the source rocks in the study area are characterized by high abundance of bicyclic and tricyclic aromatic hydrocarbons, low abundance of tetracyclic and pentacyclic aromatic hydrocarbons, relatively high abundance of fluorene, relatively high abundance of 1,2,5-TMN and 1,2,5,6-TeMN in some samples, a certain content of terrigenous biomarkers such as retene, perylene, chrysene and pyrene. All these results indicated the source rocks of Chang7 Formation were mainly developed in slightly oxidizing-reducing shore-shallow lacustrine environment. Besides, the terrestrial higher plants input had certain contribution in the formation of source rocks. The maturity parameters of alkyl naphthalene, alkyl phenanthrene and alkyl dibenzothiophene from aromatic hydrocarbons suggested that the thermal evolution stage of source rocks reached the maturity stage. Although the equivalent vitrinite reflectance calculated by different series of aromatic compounds had some differences, it could qualitatively reflect the stage of thermal evolution of source rocks.