【作者】 曹青；

【导师】 柳益群；

【作者基本信息】 西北大学 ， 矿产普查与勘探， 2013， 博士

【摘要】 本论文借助岩心观察、常规薄片、铸体薄片、扫描电镜、常规压汞测试、恒速压汞测试、岩心核磁共振测试、伊利石K-Ar测年和流体包裹体测温及组分测定等分析化验测试手段,结合盆地埋藏—热演化史及试气成果等资料,对鄂尔多斯盆地东部上古生界致密砂岩储层的成岩作用及成岩相特征进行了深入的研究；根据盆地天然气聚集的实际地质状态推算致密储层物性上下限,将其与储层孔隙致密恢复结果结合来确定储层的致密时间；并与储层内大量天然气富集成藏的时间对比耦合,从而确定上古生界不同类型砂岩储层的成岩—成藏耦合关系。研究结果表明,上古生界致密砂岩储层发生多类成岩作用,经历了漫长而复杂的成岩演化,已经演变到了中成岩B期阶段。研究区上古生界致密砂岩储层的成岩作用在粒径、分选程度、矿物组分和孔喉大小等方面显示独特性。依据成岩作用及其孔隙组合特征划分出3类成岩相,分别是硅质胶结+溶蚀孔隙相、混合胶结+溶蚀孔隙相和混合胶结致密相,并对不同成岩相内试气结果给予分析。首先采用国内外普遍采取的经验统计法,对致密砂岩气储层界限进行统计分析；从致密砂岩微观孔喉内天然气运移受力状态入手,建立孔喉半径与物性参数之间的线性回归关系,以不同受力状态下孔喉半径界限参数推算相应物性上下限参数。根据鄂尔多斯盆地天然气聚集的实际成藏状态,对其物性上下限进行推算。在确定初始孔隙度的基础上,首先恢复压实作用造成的孔隙损失量；然后根据胶结物形成序列及其含量差异,确定不同类型胶结作用造成的孔隙损失量；同理再确定不同类型溶蚀作用造成的孔隙增加量。最终按成岩演化序列将二者结合,从而还原储层砂岩的致密化过程。依据推算的上古生界致密砂岩储层致密上下限确定研究区储层致密时间,将其与储层内天然气大规模聚集富集的时间耦合分析,最终确定研究区上古生界不同类型砂岩储层的成岩—成藏耦合关系。耦合结果显示盒8段和太原组岩屑石英砂岩储层显示“先致密、后成藏”的成岩—成藏关系,山2段石英砂岩储层显示“边致密、边成藏”的成岩—成藏耦合关系。针对气源岩的生气强度、盖层封闭状态和储层致密差异等因素,对盆地东部上古生界天然气聚集条件进行详细分析；在良好的气源基础上,不同成岩演化状态的砂岩储层与泥岩隔夹层的三维配套组合控制了其内天然气的聚集程度,从而使气藏显示出三维空间内相邻或叠置的“准连续型聚集”特征。更多还原

【Abstract】 According to core observation, analysis of casting thin sections and conventional thin sections, scanning electron microscope, conventional mercury injection testing, rate-controlled mercury injection testing, core NMR testing, illite K-Ar aging, temperature and component detection of fluid inclusion and other modern testing method, combined burial and thermal evolution data of Ordos Basin, this paper made a further research on the diagenesis and diagenetic facies of Upper Paleozoic tight sand reservoirs of Eastern Ordos Basin, and predicated the physical upper and lower limit of tight reservoirs on the basis of geological characteristics of gas accumulation. Besides, based on analysis of gas injection periods and rebuilding of pore tighten process, it also can be inferred the correlation between diagenesis and accumulation of Upper Paleozoic tight sand reservoirs with different lithology.The results indicate that multi-diagenesis develop in tight reservoirs, which experienced long and complex diagenesis evolution, and up to stage B of middle diagenesis. Furthermore, diagenesis of tight sand reservoirs is uniquely characterized by grain size, sorting degree, mineral component and pore-throat size, etc. According to diagenesis and pore combination, diagenetic facies can be divided into three types, i.e. facie of siliceous cement-dissolved pores, facie of mixed cement-dissolved pores and tight mixed facie, besides, gas testing of different diagenetic facies were still analyzed.With empirical approach, found general acceptance, this paper made a research on the reservoir limit of tight gas. Based force state analyzing of gas in micro-pore-throat, a linear regressive correlation between pore-throat radius and physical attributes can be built, and then physical limit also can be calculated by corresponding pore-throat radius in different forceOn the basis of primary porosity restoration, porosity losing, caused by compaction, can be rebuilt, and then porosity losing, caused by different cementation, can also be calculated interms of cement formation sequence and content. Similarly, porosity augment, caused by dissolution, can be calculated so. Coupling analysis was accomplished to the effect between gas injection period and tighten period, defined by calculated limit of tight reservoi, and shown that reservoir tighten period of lithic-quartz sand reservoir, developed in He8Section and Taiyuan Formation, is prior to gas accumulation. However, for quartz sand reservoir of Shan2Section, reservoir tightening is almost simultaneous with gas accumulation.Detailed study on accumulation conditions of Upper Paleozoic gas, Eastern Ordos Basin, was carried out, which focuses on the gas-generation intensity, seal closing state and reservoir tight difference. The results show that, with favorable gas generation condition, three-dimensional arrangement, composed by reserve with different diagenesis evolution and mud stone, controls gas accumulation, which lead to "quasi-continuous" reservoir, characterized by bordering or overlaying distribution.更多还原