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根据对鄂尔多斯盆地中部石炭二叠系压力孕育史模拟,晚三叠世和早白垩世其烃源岩内异常流体压力均明显大于静水压力,形成2个过剩压力高峰(不同地区前、后峰的大小关系不同),之后对应的泄压段可作为两个重要排烃期,中西部的主排烃期在早白垩世—晚白垩世,东部的主排烃期在晚三叠世—中侏罗世。根据对研究区5条剖面的水动力模拟结果,认为气势分布的演化可分为3个阶段(晚三叠世至中侏罗世,早白垩世,晚白垩世至今),各阶段气势分布特征有所不同,不同阶段之间天然气运移方向变化较大。通过对层组间过剩压力分布、气势对比及奥陶系地层水和天然气化学性质的综合分析,认为沿垂直方向运移的天然气向上可到达下石盒子组,向下通过古侵蚀沟等可进入奥陶系,成为奥陶系大气田的一部分气源。图5参7(梁大新摘)
According to the pressure-history simulation of Carboniferous-Permian system in the central Ordos Basin, the pressure of anomalous fluids in the source rocks of the Late Triassic and Early Cretaceous was significantly greater than that of hydrostatic pressure, resulting in two excess pressure peaks (anterior and posterior peaks in different regions And then the corresponding pressure relief sections can be regarded as two important hydrocarbon expulsion periods. The main hydrocarbon expulsion period in the middle and western regions is from Early Cretaceous to Late Cretaceous. The main hydrocarbon expulsion period in the eastern part is in the Late Triassic Middle Jurassic Luo world. According to the hydrodynamic simulation results of five sections in the study area, it is considered that the evolution of the momentum distribution can be divided into three stages (Late Triassic to Middle Jurassic, Early Cretaceous and Late Cretaceous) The difference is that the direction of gas migration varies greatly between different stages. Through the comprehensive analysis of the distribution of overpressure between layers, the potential contrast and the chemistry of Ordovician formation water and natural gas, it is considered that the vertical migration of natural gas can reach the lower Shihezi Formation and down through the ancient erosion ditch and so on Ordovician, a part of the Ordovician gas field gas source. Figure 5 Reference 7 (Liang Daxin Abstract)