鄂尔多斯盆地延安三角洲长4+5和长6油气聚集模式

Oil accumulation patterns of Chang 4+5 and Chang 6 in Yan’an delta,Ordos Basin

李爱荣 王维喜 武富礼 赵靖舟 张惠

Li Airong Wang Weixi Wu Fuli Zhao Jingzhou Zhang Hui

延安三角洲位于鄂尔多斯盆地陕北斜坡东南部,该三角洲之上发育多个油藏,主力产油层为长4+5和长6。根据沉积相带、储盖条件和距油源距离等差异,建立了不同的油气聚集模式。三角洲沉积背景下河道主砂体的叠置发育区为油气主运移通道,油气可以远距离地垂向、侧向运移。根据油藏距油源的相对位置和油气的聚集能力,油藏可分为近源聚集区、近源逸散区和远源聚集区3种。近源聚集区和远源聚集区由于油气运移或遮挡条件有利,具有较好的油气富集条件;近源逸散区尽管距油源最近,但由于油气具有向构造高部位运移的特点,油气聚集的能力有限,往往仅具备油气运移通道的功能。综合油气运移通道的优劣与油藏所处区带位置的不同,将延安三角洲油气聚集模式分为主运移通道近源聚集、主运移通道远源聚集、次运移通道近源聚集、次运移通道远源聚集、近源逸散5种模式。

Yan'an Delta is located in the southeastern part of Shanbei slope in Ordos Basin and contains several oil reservoirs.Chang 4+5 and Chang 6 are the main pay zones.According to sedimentary facies,reservoir-seal assemblage and distance from source,this paper established several hydrocarbon accumulation patterns.The superimposed channel sandbodies in the delta are the major migration pathways for the hydrocarbon,and they provided conditions for long distance lateral and vertical migration of hydrocarbons.According to the distance between source and reservoir and the ability of oil accumulation,the reservoirs can be divided into three types,i.e,proximal accumulation,distal accumulation and pro-ximal dissipation.The former two types of accumulation areas have better oil enrichment conditions as the hydrocarbon migration and/or sealing conditions are favorable,while the later is limited in hydrocarbon accumulation capacity despite its shortest distance to oil source due to the migration of hydrocarbons to structural high.According to the migration pathways'quality and reservoir location,the accumulation pattern of Yan'an Delta are divided into five types,i.e.the proximal accumulation pattern with main migration pathways,the distal accumulation pattern with main migration pathways,the proximal accumulation pattern with sub-migration pathways,the distal accumulation pattern with sub-migration pathways and the proximal dissipation pattern.

10.11743/ogg20130513