Oriente-Maranon盆地石油地质特征及勘探潜力

Petroleum geology and exploration potential of Oriente-Maranon Basin

Oriente-Maranon盆地是古生代克拉通边缘基础上发展和形成的次安第斯山（Sub-Andeans）前陆盆地之一,经历了克拉通边缘盆地→裂谷盆地→前陆盆地3个演化阶段。盆地内主要的烃源岩及储、盖组合均发育在裂谷盆地阶段,三叠系—侏罗系Pucara群和白垩系Chonta组2套主要烃源岩的排烃高峰期分别是古新世—始新世（距今60-45 Ma）和中新世（距今15-5 Ma）。Chonta组自生自储组合是最重要的成藏组合。盆地西部发育逆冲断层/褶皱圈闭和基底卷入圈闭,中部发育挤压或披覆背斜,东部发育牵引背斜圈闭,不同类型的圈闭沿北西—南东走向呈带状分布。有潜力的勘探领域包括中西部白垩系Chonta组烃源岩供油区域的披覆和挤压背斜圈闭,中部和南部侏罗系Pucara群烃源岩供油区域的牵引背斜圈闭和挤压背斜圈闭,中部的Pucara群碳酸盐岩圈闭,北部和东部成熟探区上白垩统岩性圈闭和上古生界构造-地层圈闭。

Oriente-Maranon Basin is one of the Sub-Andean foreland basins developed and formed on the basis of Paleozoic cratonic margin.The Oriente-Maranon Basin went through three evolution phases： marginal basin of craton,rift basin and foreland basin.The phase of rift basin formed the primary source rocks and reservoir and seal.Triassic-Jurassic Pucara Group and Cretaceous Chonta Formation generated a mass of hydrocarbons in Paleocene-Eocene（60-45Ma） and Miocene（15-5Ma）,respectively.The assemblage of self-generating and self-preserving reservoir was the most important type in the Cretaceous Chonta Formation.There are basement-involved thrust traps and detached thrust faulted/folded traps in western basin,drape and extruding anticline traps in central basin,and traction anticline traps in eastern basin.The different types of traps are distributed along the NW-SE direction.Four potential exploration targets are： Drape and extruding anticline traps in the source rock drainage area in Chonta Formation in central-western basin;Traction and extruding anticline traps in the source rock drainage area in Pucara Group in central-southern basin;Pucara Group carbonate traps in central basin;Upper Cretaceous lithologic traps and Upper Paleozoic structural-stratigraphy traps in the northern and eastern exploratory area.