哈萨克斯坦斋桑盆地构造特征及其对油气成藏的影响

哈萨克斯坦斋桑盆地是中亚地区重要的含油气盆地之一,由于构造复杂导致油气富集规律认识不清,在一定程度上限制了该地区的油气勘探开发进程。基于精细的三维地震解释,结合构造演化与生烃过程、源储配置关系,通过分析盆地内不同区域不同时期的构造活动强度与油气勘探结果,对斋桑盆地的构造特征和油气成藏模式进行了系统研究。结果表明:斋桑盆地自二叠纪以来共经历了4期构造沉降和4期构造挤压反转,目前盆地形态以挤压构造为主要特征,发育叠瓦构造、对冲构造、冲起构造等多种构造样式;侏罗纪末期的逆冲断层活动控制了主区、北东区和K区的构造形态雏形,上新世末期断层再次发生挤压逆冲造就了现今的构造形态;斋桑盆地可大致分为3次大的成藏期;深层油气藏为自生自储型地层油气藏、岩性油气藏,浅层气藏分布主要受控于深层油藏的分布规模及喜山期形成的浅层逆冲背斜、断背斜等有利圈闭;印支期的构造运动对斋桑盆地的油气成藏起了非常重要的控制作用,具体表现为印支期构造运动强烈(三叠系被严重剥蚀或者该期逆冲活动强烈)的三维S井区、K构造和二维东区的M井区域,其圈闭普遍为空圈闭,钻井试油基本出水,而已钻遇的油气藏均位于印支期构造活动较弱区域。综合以上研究认为,盆地东部北缘和东部南缘应是斋桑盆地未来寻找油气藏的有利区。

Structural characteristics and its impacts on hydrocarbon accumulation in Zaysan Basin,Kazakhstan

The Zaysan Basin in Kazakhstan is one of the important petroliferous basins in Central Asia. Due to the complex structure,the oil and gas enrichment law is unclear,which limits the exploration and development process in some degree. Based on the fine three-dimensional seismic interpretation,combined with the studies of tectonic evolution,hydrocarbon generation processes,and reservoir conditions, and through the analysis of the comparison between tectonic activity intensity and oil and gas exploration results at different periods in different areas of the basin,the structural characteristics and oil and gas accumulation model in Zaysan Basin were systematically studied. The results show that Zaysan Basin has experienced four-stage subsidence and four-stage extrusion reversal since the Permian. At present,the basin morphology is dominated by extruded structures,and various tectonic styles such as imbricate structure,ramp structure and pop up structure are developed. The thrust faults activity at the end of the Jurassic period controlled the rudiment structural framework of the main area,the northeast area and the K-zone,and the present tectonic form shaped by the re-compression and thrust of faults at the Late Pliocene. The Zaysan Basin can be roughly divided into three large reservoir-forming periods. The deep oil and gas reservoirs are self-generating and self-storing stratigraphic and lithologic reservoirs,and the distribution of shallow gas reservoirs is mainly controlled by the distribution scale of deep reservoirs and the favorable traps such as shallow thrust anticlines and broken anticlines formed during the Himalayan period. The Indosinian tectonic movement played a very important role in controlling the hydrocarbon accumulation in Zaysan Basin. The S well area,the K-zone and the M-well area,where the Indosinian activity was strong(referring to the severe erosion of the Triassic strata or the thrusting activity is strong),the traps are generally empty. The drilling test oil is basically out of water, and the oil and gas reservoirs that have been confirmed are in areas with weaker activities. Based on the above research,the northern and southern margin of the eastern part of the basin should be favorable areas for the future search of oil and gas reservoirs in Zaysan Basin.