裂谷盆地深层石油地质特征与油气成藏条件

裂谷盆地是指沉积盆地在地质历史演变的某个阶段经历了裂谷时期的盆地。裂谷盆地深层在中国一般是指裂谷盆地中含油气层段埋深>3 500 m的地层,国外则指埋深>4 000 m的地层。中国东部具深层油气田的裂谷盆地主要是中、新生代盆地;全球裂谷盆地深层的大油气藏主要分布于白垩系,其次是上古生界;深层油气藏的储层形式多样,有孔隙型、裂缝型、溶洞-裂缝型及孔隙-裂缝型等;深层油气田的油气运移方向以垂向为主,圈闭则大多以岩性或与断裂有关的构造岩性圈闭为主。其次,盐岩体的活动对圈闭的形成亦十分重要,其类型则以复合型为主。

Geological characteristics of rift basin's deep buried strata and conditions of petroleum reservoir formation

Rift basins are defined as some sedimentary basins that have undergone rifting movement during a particular evolutional period in geologic history.The deep strata in rift basin are the main oil-bearing and gas-bearing intervals with burial depth more than 3500 m in China and over 4000 m overseas.Reservoirs in deep strata dominantly developed in the Mesozoic and Cenozoic rift basins in Eastern China,and huge reservoirs in global rift basins mainly occurred in the Cretaceous and the Upper Paleozoic.The types of oil reservoir in deep horizons are various,including porosity type,fracture type,dissolved cavity-fracture type,porosity-fracture type,etc.Migration direction of hydrocarbon in deep horizons was predominantly vertical.The traps were often related to lithology and faults,and thus the structural-lithologic composite traps formed.In addition,movements of halite also played an important role in the formation of traps,mainly forming composite type of traps.