厄瓜多尔奥连特盆地构造演化特征

拉美地区在世界油气资源中所处地位不断提高,奥连特盆地属于该地区勘探与开发程度较高的重要含油气盆地。为加深对奥连特盆地构造演化及其控藏规律的认识,将奥连特盆地构造演化史大体划分为古生代被动陆缘、中生代弧后裂谷及新生代弧后前陆3 个阶段。根据断裂发育及沉降–沉积特征,将奥连特盆地划分为西部次安第斯构造带、中部构造带及东部前陆斜坡构造带3 个构造单元。构造演化对该盆地油气成藏具有控制作用,中部构造带西(早)安第斯阶段多形成低幅背斜圈闭,西部、东部构造带东(晚)安第斯阶段分别以形成逆冲断背斜型圈闭和构造–岩性复合型圈闭为主。

Tectonic Evolution in Oriente Basin of Ecuador

Oriente basin is one of the important petroliferous basins of Latin American region with higher levels of exploration and development. For the purpose of in-depth understanding of the tectonic evolution and the oil accumulation controhnent in Oriente basin, the study of the sedimentary strata distribution and tectonic subsidence has been carried out through the overall consideration of MOP (Mranon-Oriente-Putumayo) petroleum province consisting of Ecuador's Oriente basin, Colombia's Putumaro basin and Peru's Maranon basin. Based on subsidence mechanism and sedimentary strata, Oriente basin is roughly divided into three stages in tectonic evolution, i.e. Paleozoic passive continental margin, Mesozoic back-arc rift and Cenozoic back-arc foreland. According to the characteristics of faults, considering subsidence-sedimentation characteristics of the entire MOP petroleum province, Oriente basin could be spatially divided into three tectonic units, i.e. the western sub-Andean belt, the central belt and the eastern foreland slope belt. Tectonic evolution has an absolutely dominant role in controlling hydrocarbon accumulation. Lots of low-amplitude anticline traps were formed mostly during the west (early) Andes episode in the central tectonic belt. Principal traps belong to reverse-thrust anticline traps and composite traps of structure-lithology formed during the east (late) Andes episode respectively in the western and eastern tectonic belts.