塔里木盆地北部于奇地区东河砂岩油气成藏与勘探前景

Oil & gas accumulation conditions and exploration prospect of Donghe sandstone in Yuqi area,Tarim Basin

东河砂岩是塔里木盆地勘探热点之一.以成盆、成烃和成藏理论为指导,应用储层预测、流体包裹体分析等技术和方法,综合研究了于奇地区东河砂岩油源条件、储集条件、保存与储盖组合、圈闭条件、油气成藏期次与成藏过程.结果表明,区内油源主要来自阿克库勒凸起南部寒武系—下奥陶统烃源岩,油源较充足,具有一定的资源潜力;储集层类型以孔隙型为主,为中等容积、中等渗透性能储层,有利的储层分布区位于于奇东部地区的东南一带;储盖组合为下储上盖式,盖层封盖能力好;圈闭类型主要为非构造圈闭,至少发生了一次油气注入成藏期即喜山早期.提出今后勘探应突破传统的构造圈闭的束缚,坚持以寻找多类型圈闭特别是地层圈闭为原则.

Donghe sandstone is one of exploration hotspots in Tarim Basin.The oil & gas source conditions,reservoir conditions,preservation conditions and reservoir-cap rock combination,trap conditions,oil & gas charge history and accumulation phases of the sandstone are studied by using the techniques of reservoir prediction and fluid inclusion analysis based on the theories of basin evolution,hydrocarbon generation and oil & gas accumulation.The results indicate that the oil & gas in Yuqi block comes from Cambrian to lower Ordovician source rock in the south of the Akekule uplift,and there is oil & gas resource potential in Donghe sandstone;the reservoir is mainly porous,and its porosity and permeability are moderate,the best reservoir is located in the south-east of eastern Yuqi block;the combination mode of reservoir and cap rock is the combination of the reservoir from the old rocks with cap rock from the young rocks,and the seal conditions of Donghe sandstone are favorable;the traps are mainly non-structural traps,there are one oil/gas charge at least,i.e.,in early Himalayan.It is held that next exploration objects in Yuqi area are non-structural traps,which provides an important theoretical fundament for the next exploration in Yuqi area and its adjacent areas.