塔南凹陷岩性油藏成藏条件与4种成藏模式

Accumulation conditions of lithologic reservoir and four types of oil accumulation mode in Tanan sag

本文分析了塔南凹陷岩性油藏的成藏条件,结果表明,开阔的复式箕状断陷结构使塔南凹陷形成了多凸多凹、凹隆相间的构造格局,为岩性油藏的形成创造了有利的空间;南屯组多沉积中心发育的优质烃源岩为岩性油藏发育提供了物质基础;同沉积断裂及其配置关系决定了塔南凹陷具有沟谷控源、转换带控扇、断坡控砂的成盆特点,水下扇中扇,三角洲前缘和远岸水下扇相带是最有利油气聚集相带;储层原油相态的变化、富含火山碎屑储层以及断裂的发育拓深了深部油气成藏的空间,为岩性油藏发育提供了有效的储层空间;构造活动及沉积演化形成了最优的生储盖空间配置关系,为多种岩性油藏类型的形成创造了有利条件。根据塔南凹陷已发现岩性油藏类型、空间分布规律及其成藏特征,结合塔南凹陷各洼槽地质结构特点以及断层一坡折类型,借鉴渤海湾、二连盆地岩性油藏成藏模式的研究认识,总结出塔南凹陷断阶型陡坡坡折带成藏模式、断阶型缓坡坡折带成藏模式、断崖型陡坡坡折带成藏模式、盆内坡折带成藏模式4种岩性油藏成藏模式。

The analyses of the accumulation conditions of lithologic reservoir in Tanan sag showed that,for the openmultiplex and half grabenlike faulted structures,the tectonic framework of the convex concave and concaveuplift alternated formed in Tanan sag,which created favorability for the formation of the lithologic reservoir; The highquality source rocks developed in the sedimentary center of Nantun Formation were material foundation of the development of the lithologic oil reservoirs; Synsedimentary fault and its configuration decided the characters of gullies controlling sources,transform zones controlling fans and faulted slopes controlling sands,and that the middle fan of subaqueous fan,delta front and infralittoral subaqueous fan were the the most favorable hydrocarbon accumulation zones; The phase changes of the oil in the reservoir,rich volcanic debris and the development of the faults make the deep oilgas accumulation more development,which provided effective reservoir space for the development of the lithologic oil reservoir; Tectonic activity and sedimentary evolution formed the optimal configuration relationships of the sourcereservoircap,which created favorable conditions for the formation of multitypes lithologic oil reservoirs.According to the lithologic oil reservoir types,spatial distribution characteristics and oil accumulation characters in Tanan sag,four kinds of lithologic oil reservoir forming modes are summarized,including the fault terracesteep slopebreak belt,fault terracegentle slopebreak belt,cliffsteep slopebreak belt and inner basin slopebreak belt reservoir forming mode of Tanan sag,combining the geological structure characters and faultslope break types of each subsag in Tanan sag and the study results of the lithologic reservoir forming mode in Bohai Bay,Erlian Basin.