Petroleum geology and exploration potential of Oriente-Maranon Basin

Abstract

Oriente-Maranon Basin is one of the Sub-Andean foreland basins developed and formed on the basis of Margin of Craton. 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 (60–45 Ma) and Miocene (15–5 Ma), respectively. There are several reservoir-seal assemblages developed in the foreland basin. The assemblage of self-generating and self-preserving reservoir was the most important type in 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; Lithologic traps in upper Cretaceous and lithology-stratigraphy traps in upper Paleozoic in the northern and eastern exploratory area. 摘要: 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。 Key words: Oriente Basin, Maranon Basin, foreland Basin, petroleum geological characteristics, exploration potential