【作者】 罗荣涛；

【导师】 王震亮；

【作者基本信息】 西北大学 ， 矿产普查与勘探， 2009， 硕士

【摘要】 鄂尔多斯盆地东北部上古生界天然气资源丰富,因其形成于海陆交互相到河流—三角洲相的沉积演化过程,后期成岩作用强烈而复杂。石炭—二叠系在不同构造演化时期具有不同的流体动力分布,深刻影响着天然气运移、成藏规律。通过分析上古生界的流体动力演化历史,结合砂体输导体的描述结果,对天然气的运聚特征和成藏机理加以剖析,具:有重要的理论和实际意义。以泥岩压实曲线法得出最大埋深时期过剩压力分布特征,再结合现今实测地层压力和包裹体测得的捕获压力为联合约束条件,利用盆地数值模拟方法对目的层的压力演化史进行模拟,得出异常压力演化史及关键时期流体动力分布特征;在三角洲沉积相的背景下研究砂体的展布特征,用储存系数、流动系数等对砂岩输导体的有效性进行描述,划分出有效输导体;利用包裹体均一温度和碳、氧同位素实验结合流体动力演化特征划分天然气的成藏期次;在以上工作的基础上,综合分析天然气的成藏机理。取得的主要认识包括:地层在延长组中下部开始出现过剩压力,高峰出现在延长组—纸坊组和石千峰组、上石盒子组;地质历史上压力发育有晚三叠世末和早白垩世末两个高峰,且后者值较大;流体动力在不同时期具有不同的分布特点,三叠纪末期至中晚侏罗世气势高值区位于研究区的东南部,早白垩世末期至晚白垩世气势高值区移至研究区西南部,研究区东北部的东胜地区一直处于低势区,为天然气运移的指向区;北部输导体靠近物源区,物性好于南部:中侏罗世—早白垩世末期为天然气的主要成藏期,成岩作用使得储层已经变致密,此时北部为优势运移方向,天然气在北、北东向的气势作用下沿着近南北向展布的输导体向北部运移,在构造鼻状构造的高点及地层上翘部位形成气藏;晚侏罗世地层开始抬升,直至今日天然气主要运移方向一直为东西向,以就近成藏方式为主。更多还原

【Abstract】 North-eastern part of upper paleozonic of Ordos basin is rich in natural gas. Late diagenesis is strong and complex, because of the evolution progress of continental oceanic interaction to delta facies. Hydrodynamic force of Carboniferous - Permian formation presents different feature in different tectonic evolution period, and it affects migration and accumulation of natural gas. It is of important theoretical and practical Significance to analyze migration and accumulation mechanism, though analyzing the history of hydrodynamic force evolution associating description of conducting tissue.Overpressure evolution history and hydrodynamic force distribution were obtained, though basin numerical simulation, for bounding of overpressure of largest buried depth period though compaction curve of mudstone, associating measured pressure and trapping pressure of inclusion. sand body distribution are researched, effectiveness of sand conducting tissue is describing using store coefficient and flow coefficient, and effective conducting tissue area divided, in the condition of delta facies. Accumulation periods are divided using homogenization temperature of inclusion and experiment of carbon-oxygen isotope. In the above, accumulation mechanism of natural gas is analyzed comprehensively.Major recognition including: overpressure occurs in the lower part of Yanchang formation. The peaks appear in Yanchang - Zhifang formation, Shiqianfeng formation and Shangshihezi formation. Two peaks are developed in late Triassic and early Cretaceous, the latter is bigger. Distribution feature is different in different period. High value area of gas potential exists in southeast part in Late Triassic to Late Jurassic, and southwest part in late Early Cretaceous to Late Cretaceous. Dongsheng area in northeast part is lying in low value area for a long time, as pointing direction of gas migration. Nearly to provenance result in physical property conducting tissue in north part is better. Main period of gas accumulation is in middle Jurassic - late early Cretaceous, when diagenism makes reservoir compact. Natural gas is drove to the north along sandstone conducting tissue affected by gas potential of north direction and accumulations in structural nose and bending place. After Structure uplift happened in late Jurassic, the main direction is east until nowadays. Gas accumulates closely of hydrocarbon kitchen.更多还原