East Venezuela盆地油气聚集与勘探潜力

East Venezuela盆地是一个大型的不对称前陆盆地,具有丰富油气资源。古生代以来,经历了晚三叠世—侏罗纪裂谷、白垩纪—始新世被动边缘和渐新世至今前陆盆地3个演化阶段。纵向上沉积地层可划分为前白垩系、白垩系和后白垩系3套巨层序。East Venezuela盆地最主要的烃源岩是Guayuta群和Tigre组海相泥页岩和碳酸盐岩。生油岩成熟度由北往南递减。北部烃源灶油气经断层、砂体长距离阶梯式向南部斜坡边缘运移。盆地最主要圈闭类型为背斜、断块、地层和岩性圈闭。Oficina组构造、构造—地层、地层圈闭组合和Naricual组构造圈闭组合是盆地内最主要的两套成藏组合。有潜力的勘探领域包括白垩系—下中新统被动边缘沉积层序、盆地中部前渊区、南部重油带和东部海域。

Hydrocarbon Accumulation and Exploration Potential of East Venezuela Basin

East Venezuela Basin is a large asymmetric foreland basin which has rich oil and gas resources.It went through three evolution phases since Paleozoic:rifting phase(late Triassic to Jurassic),passive margin phase(Cretaceous to Eocene) and foreland basin phase(Oligocene to today).Vertical sedimentary strata can be divided into three megasequences:pre-Cretaceous sequence,Cretaceous sequence and post-Cretaceous sequence.Marine shales and carbonates of the Guayuta Group and Tigre Formation are the main oil and gas source rocks in the East Venezuela Basin.The maturity of oil source rock is decreasing from north to south.Oil and gas in the northern hydrocarbon kitchen migrated stepped and long distance to the southern slope edge by faults and sand body.Anticlinal,faulted,stratigraphic and lithologic traps are commonly found in the basin.There are two mainly sets of hydrocarbon plays,structural traps/structuralstratigraphic traps/stratigraphic traps assemblages in the Oficina Formation and structural traps assemblages in the Naricual Formation.Four potential exploration targets exist in the basin:sedimentary sequence of passive margin from Cretaceous to early Miocene,foredeep of the central basin,heavy oil belt in the southern basin and offshore of the eastern basin.