吉木萨尔凹陷芦草沟组致密油系统的成藏特殊性

摘要

通过烃源岩条件、储层特征与原油类型分布及其来源、源-储配置关系的系统分析,分析了准噶尔盆地吉木萨尔凹陷芦草沟组上、下段致密油系统的自生自储与层控成藏特征.结果表明,芦草沟组咸水湖相沉积中的不同岩性均有不同含量的原始有机质,其中的泥岩有机质丰度和生烃潜力最高,为主力烃源岩,母质类型具倾油特征,处于生油阶段.位于烃源岩层系内的砂岩类与碳酸盐岩类储集层主要为低孔低渗-致密背景,含油性与物性差异存在密切关系.源-储配置表现为互层和泥包砂特征,具有源、储邻近叠置分布的致密油聚集条件.芦草沟组上、下段的原油物性与地化特征存在明显差异,分别主要来自邻近层段烃源岩.综合研究认为吉木萨尔凹陷内芦草沟组具有就近运移、自生自储的层控致密油成藏模式.%Based on the analysis of source rock, reservoir, crude oil origin and spatial configuration relationship between source rock and reservoir, it was proposed of the stratiform and self-generating and self-preserving tight oil accumulation model of the Lucaogou Formation in the Jimusaer sag of the Junggar Basin.In salt water lake facies sedimentary rocks of the Lucaogou Formation, individual lithology had different content of original organic matter which trended to generate oil, in them, as main source rock, shale has the highest organic matter abundance and hydrocarbon potential, oil-prone parent matter type and the mature stage for oil generation.The sandstone and carbonate reservoirs which were distributed in source rock layer had reservoir background of low porosity and low permeability, and their oilness has a close relationship with physical property difference.The Lucaogou Formation had basic tight oil accumulation condition because of alternating layers between shale and reservoir, and reservoir involved in shale.The crudes oil in the Upper and the Lower member of the Lucaogou Formation, which having obvious density and geochemistry differences, came from the source rocks adjent to them, respectively.Comprhansive researches show the Lucaogou Formation has stratabound tight oil accumulation model with close migration distance and self-generating and self-reservoir in Jimusaer sag of Junggar Basin.