塔里木盆地乌什凹陷石油地质特征

PETROLEUM GEOLOGIC FEATURES OF WUSHI SAG IN THE TARIM BASIN

勘探程度较低的乌什凹陷在乌参1井获得了高产工业油气流,那么该凹陷的石油地质特征和油气勘探前景如何呢?综合多种资料分析认为,该区构造演化可大致分为:泥盆—二叠纪、三叠—侏罗纪、白垩纪、早第三纪—晚第三纪中新世、晚第三纪中上新世—第四纪等5个阶段;区内发育石炭—二叠系、三叠系和侏罗系等3套主要优质烃源岩,是该区形成大中型油气藏的资源基础和保障;下第三系、白垩系储层发育,与上覆盖层组成多套储盖组合,为油气的聚集提供了场所;受多期构造运动的影响,油气成藏表现为晚期供气、晚期运聚、晚期成藏及再聚集的特征。最后得出结论:乌什凹陷具有非常优越的石油地质条件,是塔里木盆地油气勘探最为重要和现实的地区之一。

High commercial oil and gas flow has been tested in Wucan-1 well in the less-explored Wushi sag. This paper discusses the petroleum geologic features and exploration potential of this sag. It is believed based on comprehensive analysis that the tectonic evolution in the study area can be roughly divided into 5 periods, including Devonian-Permian, Triassic-Jurassic, Cretaceous, Paleogene-Neogene Miocene, and Neogene Middle Pliocene-Quaternary. Three sets of high quality source rocks, including Permo-Carboniferous, Triassic, and Jurassic, are developed and they consist of the material base for the formation of large and medium oil and gas pools. The well-developed Paleogene and Cretaceous reservoirs, which form several sets of reservoir-seal assemblages together with the overlying cap rocks, accommodate the accumulation of oil and gas. The formation of oil and gas pools is characterized by late gas generation, late migration and accumulation, late reservoiring, and secondary migration, due to the influences of multiphase tectonic movements. It is finally concluded that Wushi sag has very favorable petroleum geologic conditions, thus is one of the most important and realistic areas for petroleum exploration.