穆格莱德盆地构造地质特征与油气富集

Structural geological characteristics and hydrocarbon enrichment of the Muglad Basin

穆格莱德盆地是非洲大陆内部的裂陷盆地,其构造演化过程可以分为3个阶段:1)早白垩世早期初始裂陷阶段;2)早白垩世晚期—晚白垩世继承性裂陷阶段;3)新生代坳陷阶段。晚白垩世末,中非大断裂的走滑运动对穆格莱德盆地有强烈的改造,使得图卢斯、巴加拉凹陷在裂陷伸展基础上叠加走滑构造变形,并使穆格莱德盆地南部发生明显的构造反转。初始裂陷阶段该盆地发育有半深湖-深湖相的泥岩,是较好的烃源岩;继承性裂陷阶段发育了多种类型的砂岩储层和厚层泥岩作为区域盖层,使穆格莱德盆地具有良好的油气勘探前景。盆地后期改造方式成为油气勘探评价关注的重要地质问题。

Muglad Basin is an intracontinental rift basin in Africa, and its tectonic evolution process can be divided into three stages, including initial rifting in early of the Early Cretaceous inherited rifting in late of the Early Cretaceous to the Late Cretaceous, and depression in the Cenozoic. At the end of the Late Cretaceous, the Muglad Basin was strongly modified by the strike-slip movement of the Central African Fault, superimposing strike slipping deformation on the rifting structures of the Tullus Sag and the Bagarra Sag, and also causing an obvious tectonic inversion in south part of the basin. At the initial rifting stage, the basin was filled with semi-deep or deep lacustrine mudstones which were good source rocks; at the inherited rifting stage, the developed various types of sandstone as reservoirs and thick mudstone as regional seals. The favorable source-reservoir-cap rocks combination gives the basin large exploration potential. Later modification of the basin has been an important geological issue for evaluation of oil and gas exploration.