鄂尔多斯盆地中元古界烃源岩热演化史模拟

鄂尔多斯盆地中元古界是中国石油长庆油田天然气增储上产的潜在层系，然而长期以来对其内烃源岩热演化史一直缺乏深入研究。以PetroMod盆地模拟软件为工具，在对区内各构造单元岩性、剥蚀厚度、古大地热流值等模拟参数分析的基础上，以实测镜质体反射率（R_o）作为约束，对区内各构造单元中元古界进行热史模拟，分析不同构造单元烃源岩热演化的差异性，并结合含油气系统分析，对有利的勘探区进行了预测。结果表明:（1）盆地中元古代拗拉槽及周缘中元古界烃源岩进入生烃门限时间明显较早；除西缘冲断带中北部之外，其他拗拉槽及周缘处烃源岩各阶段成熟时间也早于其他地区，现今处于生干气阶段；除伊盟隆起地区长城系烃源岩成熟期次都较晚、现今仍处于生湿气阶段外，其他地区基本上于晚二叠世晚期进入生烃门限，现今处于生干气阶段；蓟县系烃源岩于晚二叠世晚期—中三叠世早期先后进入生烃门限，随后受盆地沉积中心不断向西迁移和天环向斜北部、渭北隆起西部早白垩世岩浆岩的侵入影响，烃源岩成熟加快，早白垩世先后进入生干气阶段。（2）渭北隆起中部、天环向斜南部、伊陕斜坡西北部、伊盟隆起中部为有利勘探区，是下一步开展研究的重点区域。 

Thermal evolution modeling of Mesoproterozoic source rocks in the Ordos Basin

The Mesoproterozoic is a potential stratum of gas accumulation and production of the Changqing oil field in the Ordos Basin. However, few recent studies have been made on the thermal evolution history of source rocks.Applying the PetroMod basin modeling software, the thermal evolution histories of the Proterozoic source rocks in each tectonic unit of the study area were simulated taking measured R_o values as calibration and based on the analyses of lithology, erosion thickness restoration and ancient heat flow. The differences of thermal evolution of source rocks in different tectonic units were discussed. Some favorable exploration areas were predicted combining with oil and gas system analyses. The results show that: (1)The hydrocarbon generation threshold of Mesoproterozoic aulacogens and peripheral source rocks is much earlier than others. The maturation stage of other aulacogens and peripheral source rocks is also earlier than others except for the mid-northern part of the western margin thrust belt, and it is in a stage of dry gas generation at present. The source rocks in the Changcheng System reached the hydrocarbon generation threshold at the end of the Late Permian and are generating dry gas now, except for those in the Yimeng uplift, which became mature late and are still generating wet gas. The source rocks in the Jixian System reached the hydrocarbon generation threshold from the end of the Late Permian to the beginning of the Middle Triassic, became mature as the basin depositional center migrated continuously to the west and influenced by intrusions in the northern Tianhuan syncline and western Weibei uplift, and finally entered the dry gas stage in the early Cretaceous. (2)The central area of the Weibei uplift, southern Tianhuan syncline, northwestern Yishan slope,and the central part of the Yimeng uplift in the Ordos Basin are favorable exploration areas.