Maranon盆地油气地质特征及勘探潜力

以地质、地球物理数据为基础,结合前人研究成果,对Maranon盆地演化与油气地质特征进行了详细的分析.研究表明:Maranon盆地是一多旋回次安第斯山前陆盆地,经历了古生代克拉通期、三叠纪—侏罗纪伸展断陷期、白垩纪拗陷期和晚白垩纪后前陆期4个构造演化阶段,纵向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.盆地内含有白垩系Chonta/Napo组和三叠—侏罗系Pucara组2套主力烃源岩及多套储盖组合.油气运移方式为垂向运移、侧向运移和阶梯式运移.盆地主要发育西部挤压断层和褶皱圈闭、中部背斜和披覆背斜圈闭、东部断层和牵引背斜圈闭等构造圈闭,可能发育岩性、地层圈闭.不同类型圈闭呈北西—南东向条带状分布.前陆坳陷带构造-地层和岩性圈闭、褶皱冲断带区古近纪构造圈闭以及东部斜坡带地层和岩性圈闭是盆地的有利勘探潜力区.

Petroleum geological characteristics and exploration potential of Maranon Basin

The evolution and petroleum geological features in the Maranon Basin are analyzed in detail based on the geological and geophysical data,combined with the results of previous studies.The study result shows that:Maranon Basin is a multi-cycle sub-Andean foreland basin.It went through four evolution phases:cratonic period(Palaeozoic),extensional faulting period(Triassic-Jurassic),depressing period(Cretaceous) and foreland period(post late Cretaceous).Vertical deposition can be divided into three megasequences:pre-Cretaceous sequence,Cretaceous sequence and post-Cretaceous sequence.Two sets of major source rocks,Cretaceous Chonta/Napo and Triassic-Jurassic Pucara Formations,and multiple sets of reservoir-cap assemblages are developed in the basin.There are three modes of hydrocarbon migration:vertical migration,lateral migration and step migration.Multitude types of structural traps are developed,including compression faulted and anticline traps in the western basin,anticline and drape anticline traps in the central basin,and faulted and traction anticline traps in the eastern basin.Different types of traps are distributed as strip belts along the NW-SE direction.It maybe developed lithologic trap and stratigraphic trap.There are three potential exploration targets in the basin:structural-stratigraphic trap and lithologic trap in foreland depression belts,structural trap of Paleogene in anticline thrust belts and stratigraphic trap and lithologic trap in the eastern slope zone.