【作者】 刘晶晶；

【导师】 罗晓容；

【作者基本信息】 西北大学 ， 地球探测与信息技术， 2010， 硕士

【摘要】 储层中的流体真实记录了沉积成岩过程中流体的成分、温度、盐度和压力等信息,直接反映了沉积盆地内油气等流体矿产的分布状况和生成演化。陇东地区地处鄂尔多斯盆地西南部,油气勘探的主要目的层为中生界延长组,沉积体系分布受长期继承性整体升降运动下形成的广阔斜坡构造背景的控制,油气运聚成藏条件复杂,但研究薄弱。因此,应用储层流体分析技术解释油气运移聚集历史和研究油气的分布与变化,在认识石油成藏规律和指导石油勘探方面,具有一定的理论意义与实践意义。本文在沉积埋藏史和成岩作用及成岩序列研究的基础上,运用流体包裹体系统分析和热动力学模拟技术,讨论了流体活动时期研究区的温-压场特征。然后进行油层中碳酸盐碳、氧同位素测试,分析了与油气活动相关的热流体的来源情况。进而结合自生伊利石的测年分析,在流体包裹体研究的基础上进行油气成藏期次划分、成藏年代确定和古流体势场的恢复。最终探讨了流体活动对油气成藏的影响。取得的主要认识有：①研究区长81段砂岩储层检测出有两期油气充注活动,两期流体活动时研究区普遍发育超压,早期油气充注发生于早白垩世早期,包裹体的均—温度范围主要为85-115℃,平均过剩压力为2.10MPa,晚期油气充注发生于早白垩世末期,包裹体的均一温度范围为110-130℃,过剩压力的平均值近似为5.5MPa。②油层中的碳酸盐矿物与碳酸盐胶结物形成与有机酸脱羧作用有关,油源流体的运移过程中伴随着热流体的共同作用,热流体来自于区域上的岩浆侵入及变质水的沉淀作用。③早白垩世末期白豹—华池—庆城—宁县一带的油势达到最大值,并分别向东西两侧降低,油势梯度值大于8m／Km优势指向区为镇原地区、合水地区及庆城的以北,以东北地区。更多还原

【Abstract】 During petrogenetic process, the composition, temperature, salinity and pressure of the reservoir fluid were recorded, which directly reflects the distribution and generation evolution of hydrocarbon in sedimentary basin. Longdong area located in southwest of Ordos Basin with its subject reservoir Triassic Yanchang formation and its depositional system was controlled by the tectonic setting of broad slope. The conditions of hydrocarbon migration and accumulation is much complex while the research of that is weak. Therefore it is meaningful to study the history of hydrocarbon migration and accumulation and the features of its distribution and diversification. Based on the analysis method of reservoir fluid, it can be helpful to understand the regular pattern of hydrocarbon accumulation, which can be used to guide oil exploration.Based on the research about the burial history and digenesis sequence of the Yanchang formation in the area, the characteristics of temperature and pressure fields was discussed during the period of the hydrocarbon charging, with the systematic fluid inclusion analysis and the technique of fluid inclusion thermodynamics modeling. And then the source of the hydrothermal fluids which related to the hydrocarbon charging was determined by means of the C and O isotopic analysis in the carbonate of Chang 8 reservoir. On the basis of results of the rauthigenic illite isotopic dating and the study of the fluid inclusion, the different periods of hydrocarbon filling and accumulation were ascertained and the paleo-fluid potential was reconstructed. Finally, the hydrocarbon migration and accumulation influenced by the fluid activity were discussed.The main understandings were listed as follows:①Two events of hydrocarbon charging had occurred here, and the overpressure is generally developed in the study area. The first hydrocarbon charging happened in the early stage of the early Cretaceous,while the homogenization temperature of fluid inclusions were predominantly 85～115℃, the average excess pressure was 2.1MPa.The second in the end stage of the early Cretaceous, the range of the homogenization temperature of fluid inclusions is 110～130℃, the average excess pressure approximately was 5.5MPa.②The generation of the carbonate of Chang 8 reservoir was related to the organic acid decarboxylation, and during migration, the oil source fluids were associated with the interaction of the hydrothermal fluids which were derived from magma intrusion or precipitation of the metamorphic water.③In the end stage of the early Cretaceous, the oil potential was the maximum in the area of Baibao-Huachi-Qingcheng-Ningxian, and to the east and west sides were reduced. The advantage hydrocarbon accumulation zone pointed to the Zhenyuan area, Heshui area and north and northeast of the Qingcheng area, the oil potential gradient in above area were all greater than 8m/Km.更多还原