Oil Migration Model and Entrapment Epoch of North Wuerxun Depression in Hailaer Basin
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摘要: 海拉尔盆地由多个凹陷构成, 油气潜在资源丰富.研究含油凹陷油气的来源、油气充注方向及成藏时间对指导盆地油气勘探具有理论和现实意义.以乌尔逊凹陷为例, 采用生物标志化合物及含氮化合物定量分析技术, 研究了石油的来源及运移方向; 利用自生伊利石K-Ar同位素测年法、源岩生排烃史法及储层流体包裹体测温法, 探讨了石油成藏期.结果表明, 原油主要来源于凹陷南部“烃源灶”内的南屯组生油岩, 油气成藏中发生了侧向运移.通源大断裂是油气运移的主要通道, 断层两盘的构造圈闭是油气聚集成藏的有利部位.苏仁诺尔构造带石油沿断裂向北东方向运移, 最大距离可达20 km.乌尔逊凹陷有3次成藏期, 其中距今100 Ma左右的伊敏组沉积末期是该区的主要成藏期.凹陷中随油藏与“烃源灶”距离的减小, 成藏期呈现逐渐变晚的趋势.Abstract: Based on the organic geochemical analysis of oils and source rock in Wuerxun depression, Hailaer basin, hydrocarbons are thought to be derived from the Nantun Formation in south Wuerxun depression and to enter the oil pools through lateral migration. Apparent migration pathways along the Surennuoer fault belt can be traced by means of absolute abundance of pyrrolic nitrogen compounds and biomarkers from the oil samples. The results indicate that the large fault is the dominant pathway in which the oil can migrates for a long distance, and fill easily into the traps near the fault. According to the migration effects of pyrrolic nitrogen compounds in the oils, the maximum migratation distance is estimated to be about 20 km. The analysis of K-Ar illite age, fluid inclusion and history of source rock expulsion indicates that there are three oil filling and entrapment events, the major oil entrapment epoch occurrs in the Late Yimin period about 100 Ma before the present. It can be also observed that the farther the pools away from the source kitchen are, the earlier the ages of oil filling are.
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Key words:
- Hailaer basin /
- Wuerxun depression /
- oil migration /
- entrapment epoch
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表 1 海拉尔盆地乌尔逊北部原油生物标志化合物参数
Table 1. Biomarker parameters of oils in north Wuerxun depression
表 2 自生伊利石K-Ar法同位素测年数据
Table 2. Data of authigenic illite K-Ar isotope
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