中非Muglad盆地1/2/4区块白垩系构造特征与油气分布

Structural characteristics and hydrocarbon distribution of Cretaceous at 1/2/4 blocks in Muglad Basin,Central Africa

中非Muglad盆地由多个以中生代沉积为主的裂谷凹陷组成,各凹陷分割性强,有独立的构造和沉积体系。通过对Muglad盆地1/2/4区块多个构造层系的地震层位解释及构造演化剖面的制作,分析了构造演化特征、断裂特征以及油气聚集的关系。研究区发育5条较大的呈NW向展布的同沉积断裂和东部两条呈NNW向延伸的盆地边界断裂,构造格局主要受这两组断裂控制,白垩系构造格局具有继承性。东部构造带受NW和NNW向正断层控制,西部构造带主要受NW向断裂控制;东、西分带明显,具"一隆二凹两斜坡"的特征,南、北成藏具有分区特点,北部主要为Abu Gabra(AG)组及Bentiu和Aradeiba组成藏组合,南部以Bentiu和Aradeiba组成藏组合为主。Kaikang凹陷东、西两侧盆地结构及构造演化差异,造成两侧油气丰度的不同。

Muglad Basin formed by a number of rift sags domained by mesozoic sendiment,the sags are relatively independent with separate tectonic systems and sedimentary systems.After seismic horizons interpretation and structure evolution profile mapping at many structural strata at 1/2/4 blocks in Muglad Basin,we analyzed the relationship among structural evolution characteristics,faults features and hydrocarbon accumulation.There are five major contemporaneous faults along NW direction and two boundary faults along NNW direction in the eastern of the study area.The frame of the 1/2/4 blocks structure is controlled by the two groups of faults,and the Cretaceous depressions and uplifts were featured by inheritance.The structural belt is controlled by NNW faults in the east,and controlled by NW faults in the west.The eastern and western structural belts are easily distinguished.The two structural are characterized by the tectonic framework of 'one uplift,two sub-depression and two slopes' and have different hydrocarbon accumulation zones in northern and southern.Hydrocarbon is mainly distributed at Abu Gabra(AG)group,Bentiu and Aradeiba group in the northern and at Bentiu & Aradeiba group in the southern.The different hydrocarbon abundance of both sides of the Kaikang depressed was due to the difference basin structrue and tectonic evolution between the east side and the west one.