【作者】 杨建；

【导师】 王国芝；

【作者基本信息】 成都理工大学 ， 矿物学、岩石学、矿床学， 2011， 硕士

【摘要】 流体是将构造变形与保存条件评价相联系的桥梁和纽带,多期构造变动必然会造成多期流体释放,查明一个研究区的流体特征,有助于进一步对油气保存条件和储存条件进行有效的评价。石柱复向斜带是中扬子区块上的一个北东向构造单元。论文探索了如何采用锶、碳、氧同位素地球化学方法示踪流体的来源和运移轨迹。具体作法是:采集围岩和孔洞缝充填物配对样品进行同位素地球化学分析,将孔洞缝中充填物的锶同位素与寄主地层和同时代海水的锶同位素进行对比,同时结合碳氧同位素特征分析,确定流体是内源流体还是外源流体。将同位素地球化学示踪方法与流体包裹体研究相结合,对石柱复向斜带上的单井和剖面中流体进行了地球化学示踪,建立了各单井和剖面的流体运移模式。在各单井和地表剖面流体来源研究的基础上,建立了整个石柱复向斜带内海相碳酸盐岩地层中流体的运移模式。研究表明,复向斜带内存在两个流体体系,它们分别是下部流体体系和上部流体体系。下部流体体系主要发育于震旦系灯影组-奥陶系地层中,上部流体体系发育于志留系-中三叠统地层中,上下流体体系间具有一个流体封隔层。复向斜带的东北部到中部地区下部流体在封隔层的作用下被封堵在下伏震旦系-奥陶系地层中;在上覆二叠系、三叠系和石炭系地层中存在多个流体封存箱,箱内流体仅在箱内发生局域性流动,箱内流体和箱外流体无交换。复向斜带靠近西南部位的地方,流体封隔层被断层破坏,下部流体通过断层提供的通道运移到上覆的奥陶系、二叠系和三叠系地层中。复向斜西南边缘部位再次显示封隔层对下部流体起到封堵作用,封隔层之上的志留系-中三叠统地层中局部存在流体封存箱。对岩芯中沥青和热液改造白云岩的序次研究,确定了热液改造时间位于大规模油藏充注之前。87Sr/86Sr介于0.7092~0.7097之间的一期热液,对白云岩储层具有明显的改造作用,受该期热液改造后的白云岩其储集空间得到明显的改善和提高,进而为后期大规模的油藏充注提供了足够的储积空间。将受热液改造的白云岩和未受热液改造的白云岩对比得知,受改造的白云岩和未受改造的白云岩的MgO、CaO、FeO、MnO等主要成分并未出现明显的变化,另外,发现受过热液改造的白云岩与国外典型的构造热液白云岩具有可对比性,表现出碳氧同位素明显负偏,锶同位素明显正偏的特征。更多还原

【Abstract】 Fluid is the bridge and link between preservation conditions and tectonic deformation.Poly-cycle Tectonic deformation resulted in the release of multi-stage fluid.Identifying the fluid characteristics of a research area can contribute to evaluating the preservation conditions and storage conditions. Shizhu synclinore zone is a NE–trending tectonic unit of central Yangtze.In this thesis , have searched a way which how to trace the origin and migration trajectory of fluid by the 87Sr/86Sr,δ18O andδ13C geochemical method.The method is that collecting the fillings in vugs and fissures and their host rocks to analyse their isotopes geochemistry features and then compare the 87Sr/86Sr of fillings in vugs and fissures with the 87Sr/86Sr of their host rocks and Contemporaneous seawater and combine withδ18O andδ13C analysis to determine these fluids were from host rocks( endogenous fluid) or from other stratas (allogenetic fluid).Combining the 87Sr/86Sr,δ18O andδ13C geochemical method with fluid inclusion studies, traced the origin and migration trajectory of fluid in every single well and sections . Established fluid migration model of every single well and sections .At the basis of studying the fluid origin of very single well and sections ,Established fluid migration model of marine carbonates strata in Shizhu synclinore zone,The study shows that there are two fluids system in the synclinore zone.They are lower and upper fluid system. lower fluid system developed in the lower Sinian - Ordovician stratas , upper fluid system developed in the Silurian - Middle Triassic stratas.There is a isolated interval between the upper and lower fluid system.The lower fluid system was blocked under the isolated interval within the Sinian - - Ordovician strata in the Northeast to the central of synclinore zone.There are multiple fluid compartments in the overlying Permian, Triassic and Carboniferous stratas , the fluid inside flow in the compartments and not exchange with the fluid outside .Close to the southeast of synclinore zone, faults destroyed the fluid compartments , lower fluid transported to the overlying Ordovician, Permian and Triassic stratas through the channel provided by the fault.In the southeast of synclinore zone,the lower fluid was sealed by the isolated interval. Local fluid compartments exist in the Silurian - Middle Triassic stratas.By researching the sequence of asphalt and hydrothermal alteration dolomite of core,ascertained that hydrothermal alteration dolomite is before the filling of large-scale reservoir.Hydrothermal fluid 87Sr/86Sr ratio between 0.7097 and 0.7092 had obviously effect on improving hydrocarbon pore volume of dolomite. Hydrothermal fluid transformation dolomite and without hydrothermal fluid transformation dolomite owned the same major composition like MgO, CaO, FeO, MnO and so on. Furthermore, hydrothermal fliud transformation dolomite had good comparison with abroad typical pattern of structural hydrothermal dolomite, it showed obviously negativeδ18O andδ13C and obvious positive 87Sr/86Sr.更多还原