【作者】 樊爱萍；

【导师】 冯乔；

【作者基本信息】 西北大学 ， 岩石学、矿物学、矿床学， 2004， 硕士

【摘要】 鄂尔多斯盆地上古生界作为目前主力天然气勘探层系，具有河道砂体发育、砂体厚度大，含气层位多的特点。有着巨大的产能和广阔的勘探前景。开展天然气成藏研究，对于加快该区天然气勘探步伐有着非常重要的作用。本文通过苏里格庙、榆林等气田上古生界天然气储集层流体包裹体的详细研究，确定了成藏温度、成藏期次、成藏时间以及保存条件，为天然气勘探提供了重要的理论依据。 在显微镜下对包裹体的形态、大小、丰度、排列、颜色、相态等进行初步观测，划分包裹体类型、并观察其基本特征。同时结合成岩作用研究，确定包裹体形成期次。 测试不同成岩阶段自生矿物中流体包裹体的均一温度、冰点、盐度、密度、和流体成分等参数。并在此基础上，按照包裹体（单一包裹体、同期自生矿物包裹体和同种成岩自生矿物包裹体等）的类型以及不同的形成期次对测试数据进行了分析和处理。 包裹体测试结果表明，鄂尔多斯盆地上古生界天然气充注与成减期次基本上有3期，分别介于152～141Ma、123～120Ma、110Ma左右。其中苏里格庙和盆地东部神木—米脂气区发育前2次充注；乌审旗气区气体充注与成藏时间最长，发育次数也最多；而榆林仅发育1次天然气的充注与成藏，此结果与构造热事件等符合。 鄂尔多斯盆地上古生界储层包裹体中的流体以NaCl—H₂O盐水体系为主，此外为极少量的CaCl₂—H₂O或NaCl-MgCl₂—H₂O体系。NaCl—H₂O盐水体系盐度较高，反映研究区上古生界储集层处于相对封闭的环境中，难以发生大规模流体的运移。这种相对稳定的水动力条件十分有利于天然气藏的保存。更多还原

【Abstract】 As the main strata of natural gas exploration at current, the Upper Paleozoic reservoirs of the Ordos basin was provided with well-developed riverway sandstones, great thickness of sandstones and multiple gas-bearing formations. It took on gigantic output capacity and wide exploration foreground. In order to acclerate the pace of gas exploration in the researched area, it was essential to develop gas accumulation research. Based on particular research on fluid inclusions of gas reservoirs in the Upper Paleozoic in the Suligemiao and Yulin gas field, the accumulation temperature, accumulation periods and conservation condition of the gas pool were respectively estimated. So the important theoretical evidence for gas exploration was offered.Some primary features of fluid inclusions, such as shape, size, color, abundance ratio, distribution, and phase etc, were observed and recorded. Fluid inclusions were divided into different types according to the features. Combined with diagenesis study, the forming stages of fluid inclusions can be established.A great deal of data of fluid inclusions in autogenetic minerals of different diagenetic stages such as homogenization temperature, melting temperature, salinity, density, and liquid composition etc, were detected. Through using different stages and types of fluid inclusions(singular inclusions , inclusions in autogenetic minerals of the corresponding period, and inclusions in the same kind of autogenetic mineral), these data were analyzed and dealed with.It was made clear that there were three main periods of the filling and accumulation of natural gas in the area, which respectively were 152~141Ma, 123~120Ma and about 110Ma. Geochemistry data indicated that the former two filling event of natural gas were developed in the Suligemiao and Shenmu-Mizhi gas field, the Wushenqi gas field underwent the whole filling history and only one filling event was developed in the Yulin gas field. The results were consistent with tectonic geothermal events in the researched area.The information of fluid inclusions demonstrated the Upper Paleogroundwater of the Ordos basin was dominated by NaCl - H2O system in addition to very few CaCl2 -H2O or NaCl-MgCl2 - H2O systems. The high salinity of NaCl -H2O system reflected the reservoirs in the Upper Paleozoic in the Ordos basin were located in the relatively close circumstance and the migration of fluid seldom occurred. Therefore, this stable hydrodynamic condition could keep the natural gas pool from destructing.更多还原