【作者】 马婷；

【导师】 赵靖舟；

【作者基本信息】 西安石油大学 ， 矿物学、岩石学、矿床学， 2010， 硕士

【摘要】 本文针对榆林-子洲地区上古生界太原组、山西组、石盒子组及石千峰组含气层段的120片流体包裹体样品进行了详细研究,测试了不同成岩阶段自生矿物中流体包裹体的均一温度、冰点温度并计算了盐度、密度和流体势等参数。在此基础上,确定了天然气成藏时间,分析了天然气的主要聚集区域。显微镜下观察包裹体的岩相学特征表明,其宿主矿物主要是石英,在石英颗粒中、次生加大边和愈合裂隙均有产出。包裹体一般个体较小,形状多以圆形和椭圆形为主。由于类型不同,颜色有无色透明、褐色、灰黑和深褐色等。垂向上从太原组到石盒子组烃类包裹体丰度减小,个体逐渐变小；平面上从南向北含气态烃包裹体的气液比逐渐减小。根据其相态组分将研究区各层段流体包裹体划分为盐水包裹体、含气态烃盐水包裹体、气态烃包裹体、含石盐子晶的盐水包裹体及CO2三相包裹体五种类型,其中含气态烃包裹体含量居多,说明该区油气演化程度较高。通过对研究区包裹体的成分分析,对比不同层段气态烃包裹体及气藏内甲烷碳同位素的变化趋势分析发现,太原组、山西组和盒8段内气态烃包裹体内甲烷碳同位素相对较轻,而现今气藏内甲烷碳同位素整体较重。盒8段、山西组和太原组由北向南包裹体内CH4组分含量逐渐增大,表明研究区南部热演化程度较高。综合分析认为现今气藏是一个累积聚气的结果,而且仍然保持动态分馏过程。利用流体包裹体均一温度结合沉积埋藏史得出研究区内各个层段油气充注期次及时间。太原组有两期油气充注：第一期距今200-180Ma,为早侏罗世；第二期160-120Ma,即J22-K12.山23气藏经历两期烃类气体的充注,第一期距今200-170Ma,J11-J21；第二期为160-115Ma,J22-K12。石盒子组盒8段气藏也经历两期烃类气体的充注,第一期为距今190-175Ma,J12-J2；第二期为155-125Ma,J3-K12。这三个层位的天然气均以第二期的充注为主力充注期。石千峰组千5段气藏经历一期充注,充注时间为170-140Ma,为晚侏罗世。恢复古流体势得出：盆地内部的流体运移主要以东北-西南向为主,基本上从西南部向中心和东北部运移。盆地西南部在燕山末期为相对高势区,周边古流体势值逐渐减小,尤其是向北东方向古流体势梯度较小,成为油气运移的主要指示区。更多还原

【Abstract】 In this paper, we researched 120 slices of fluid inclusions in Taiyuan, Shanxi, Shihezi and Shiqianfeng formations of Upper Paleozoic in Yulin-Zizhou area, through testing homogeneous temperature and freezing point of fluid inclusions in different diagenetic stages and calculating salinity, density and fluid potential to determine the accumulation periods of gas pool and finally point out the gas main gathering area.By observation on inclusion petrography, the host minerals of fluid inclusions are mainly quartz, and fluid inclusions output in quartz particles, the secondary side and healed cracks in quartz. They are mainly small in shape, mostly round and oval-based. Because of different types, they are different in color, some are transparent, brown, gray-black and dark brown and so on. Vertically from Taiyuan to Xiashihezi, the abundance of hydrocarbon inclusions decreases, the individual gradually becomes smaller; from south to north, the gas-liquid ratio of containing gaseous hydrocarbon inclusions decreases. Because of differences in phase composition, we divided the fluid inclusions in the study area into five types. The majority type is containing gaseous hydrocarbon inclusions, which implies that a higher degree of gas evolution in this area.By analyzing the composition features of inclusions and comparing methane carbon isotope trend of gaseous hydrocarbon inclusions and gas reservoir in different layers, the methane carbon isotope of gaseous hydrocarbon inclusions in Taiyuan, Shanxi group and He8 is relatively light, while the methane carbon isotope of present reservoir is heavier overall. The CH4 component in He8, Shanxi and Taiyuan increases from north to south, suggesting that the higher degree of thermal evolution of the south. Comprehensive analysis that the present gas reservoir is a cumulative result of gas accumulation, and still maintain the dynamic fractionation process.The hydrocarbon charging period are decided by inclusion homogeneous temperature and terrestrial heat history. It can be divided into two times in the Taiyuan formation, of which the first accumulation time of the Early Jurassic period and the second accumulation time of the late of the Middle Jurassic to the late of the Early Cretaceous period play great significant roles in the gas accumulation here.There are two gas accumulation times in the Shanxi formation.The first accumulation time is the early of Early Jurassic to the early of the Middle Jurassic period. The second accumulation time of the late of the Middle Jurassic to the late of the Early Cretaceous period and the last one play great significant roles in the gas accumulation here.It can be divided into two times in the Shihezi formation, of which the first accumulation time of the late of the Early Jurassic to the the late of the Middle Jurassic period and the second accumulation time of the Late Jurassic to the late of the Early Cretaceous period play great significant roles in the gas accumulation here.The gas accumulation time of the Shihezi formation is the Late Jurassic to the late of the Early Cretaceous period.Natural gas carbon isotope analysis showed that the Upper Paleozoic of Ordos Basin, gas lines with different content of methane carbon isotope heavier, has the characteristics of coal gas. Ethane, propane carbon isotope are typical characteristics of coal into a gas. Comprehensive analysis that at a gas reservoir is the result of a cumulative gas gathering, gas reservoir present within the distillation process remains dynamic.Through restorating fluid potential obtained that fluid migration in the basin mainly northeast-southwest oriented, essentially from the southwest to the center of the basin and northeast. The southwest of basin has the relatively high potential at the end of the Yanshan period, but the surrounding has the low fluid potential, especially in the northeast of the basin has low fluid potential gradient as the main migration area.更多还原