【作者】 米敬奎；

【导师】 肖贤明；

【作者基本信息】 中国科学院研究生院（广州地球化学研究所） ， 地球化学， 2003， 博士

【摘要】 鄂尔多斯盆地是我国第二大含油气盆地，其上古生界天然气藏与阿尔伯达深盆气藏相比具有许多相似的特点，目前存在的关键问题是对该气藏的成藏机理和成藏模式认识不清。本研究对采集的鄂尔多斯盆地上古生界100多块储层样品和20多块源岩样品进行了详细地分析，利用所获得的流体包裹体信息结合盆地的沉积史与热史，对上古生界油气的运移及充注历史进行了详细的研究。在此基础上利用生烃动力学和同位素动力学方法对该气藏的成因以及成藏模式进行了研究与探讨。本研究取得如下主要成果与认识： 1．鄂尔多斯盆地上古生界储层中包裹体非常丰富，但个体较小，以无荧光包裹体为主，仅在东北部的低演化区域发育有少量蓝色荧光的石油包裹体。研究结果表明：气体包裹体含量以及气液两相包裹体的气液比，从南向北呈现出逐渐降低的规律。储层中三相包裹体以及沸腾包裹体的存在，说明在包裹体的形成过程中流体并非完全均一的流体。 2．建立起一种利用石油包裹体与同期盐水包裹体等容线方程计算包裹体捕获温度和捕获压力的新方法。利用该方法计算出鄂尔多斯盆地上古生界储层包裹体的捕获温度和捕获压力分别为85—145℃、22-32 Mpa。包裹体的捕获压力远小于其形成时地层的静水压力。包裹体的捕获温度和捕获压力均具有从南向北都逐渐降低的趋势。 3．结合区域地质背景资料，提出了应用流体包裹体捕获温度求取天然气藏形成时间的方法。据此方法的计算结果表明：鄂尔多斯盆地上古生界气藏最早于-150Ma左右(晚侏罗纪)在延安附近开始形成，随后气水界面逐渐向北推移；到-110Ma(晚白垩纪)该天然气藏最终形成。天然气的区域运移方向是由南向北。晚白垩纪后，由于构造运动的影响，气藏发生了小规模的迁移和调整。 4．热模拟实验结果及生烃动力学计算结果表明在盆地抬升的过程中，烃源岩仍有一定数量气体生成。气源岩生气结束的是晚白垩纪—晚第三纪，并具有东早西晚的特点。 5．碳同位素动力学计算结果表明鄂尔多斯盆地上古生界天然气甲烷碳同位素和本地区源岩演化存在明显的不一致性，天然气藏运聚模式属阶段累积，气源摘要区主要在盆地南部高成熟区域。 6.鄂尔多斯盆地上古生界天然气藏(主要指伊陕斜坡)的圈闭类型主要是岩性气藏与深盆气藏，苏里格气田为深盆气藏，榆林气田与神木气田为岩性圈气藏。 本研究成果对认识鄂尔多斯盆地晚古生界气藏的成藏规律提供了许多有价值的信息，对于该区油气勘探研究与开发具有重要的指导意义。更多还原

【Abstract】 The Ordos Basin is the second size basin rich in oil and gas in China mainland. The Upper Paleozoic gas reservoir in this basin has some similarities with the Alberta deep basin gas trap in Canada. The key problem for the gas pool is that the formation mechanism is not clear.In this study, more than 100 reservoir sandstone samples and 20 source rock samples were taken from this basin and investigated by the combination method of geochemistry and geology, including fluid inclusion techniques, PVTsim software, thermal simulation experiments, hydrocarbon generation kinetics and carbon isotope kinetics. The following recognition and conclusion are obtained:1. The fluid inclusions occurred in the Upper Paleozoic reservoir sandstones in Ordos Basin are abundant, with small size. Most of them are non- fluorescence, and only a small amount of blue fluorescence inclusions were found in the samples from the east area of the basin where the maturity of the source rocks is lower. The amount of gas inclusions and the ratios of liquid to gas in aqueous inclusions are decreasing from the south to the north in the basin. The present of the three-phase inclusions and boiling inclusions indicate that the fluids was not homogeneous when the inclusions formed.2. A new method was suggested to calculate the trapping temperature and pressure of inclusion using the isochore equations of both petroleum inclusion and its coeval aqueous inclusions. The trapping temperature and pressure of aqueous inclusions occurred in the Upper Paleozoic reservoir sandstones are in the range of 85-145# and 22-32Mpa, respectively. The trapping pressures of inclusions are lower than the strata water static pressure when the inclusion was trapped. The trapping temperatures and pressures of the fluid inclusions are decreasing from the south to the north of the basin.3. The Upper Paleozoic gas pool formed firstly in the Yanan area before 150Ma (Late Jurassic). With the migration of water-gas interface from the south to the north gradually, the gas-bearing area extended, and framework of the gas pool formed finally in 110Ma (the late Cretaceous). From the Late Cretaceous to present, the gas trap has been adjustedbecause of the tectonic movement. Combining all kinds of information of inclusions with the geologic background, it is recognized that the regional migration of gas was from the south to north direction.4. The results of the thermal simulation experiments and the kinetics calculation of hydrocarbon generation have shown that the source rock can generate a significant amount of gas in the process of tectonic uplifting. The gas generation of the source rocks in the basin ceased from the late Tertiary to the late Cretaceous, with the trend later in the west area and earlier in the east area.5. The results of the carbon isotope kinetic have shown that the gas carbon isotope values in the Upper Paleozoic gas reservoirs areas not consistent with the maturity of the source rocks from the gas pool areas. The formation of the gas pools belong to stage accumulation model and the main source are in the south area with higher maturity.6. There are two main types of gas trap in the Upper Paleozoic strata .One is lithological gas trap, and another is deep basin gas trap. The SuLiGe gas pool is a deep basin gas trap, and the YuLi and ShenMu gas pools are lithologyical gas traps.The results have provided some important information on the formation of Upper Paleozoic gas pools, having great significance for further research and exploration of the Ordos Basin更多还原