济阳坳陷青东凹陷沙河街组四段上亚段沉积体系研究

Sedimentary System the Es_4~u of Shahejie Formation of Qingdong Sag in Jiyang Depression

青东凹陷是受走滑断裂影响、区域拉张作用控制而形成的新生代陆相断陷湖盆,是胜利油田勘探程度较低地区,同时也是近期勘探的热点和重点地区。利用测录井、取心和地震资料,对青东凹陷沙河街组四段上亚段(Esu4)沉积及演化特征进行了研究。结果表明,该区存在3大物源-沉积体系,即北部以垦东凸起为物源的近岸水下扇沉积体系、西部以青坨子凸起为物源的扇三角洲-湖相沉积体系及东南部以潍北凸起为物源的三角洲沉积体系。Esu4沉积体系发育主要受古地貌、断层活动的联合控制,"四周环凸、垒堑相间"的古地貌导致多物源体系、多沉积类型并存;NNE、近EW、NWW向3组断裂系统活动形成的断沟、断坡及沉积中心变化控制了沉积体系空间分布。凹陷主体呈现近东西向展布的沉积格局,东部受郯庐断裂控制主要呈北东向展布。

Qingdong Sag was a Cenozoic continental fault basin formed by the sliding fault-system and regional strike forces.Its exploration degree was lower in Qingdong Sag of Shengli Oilfield and at the same time it was the hot spot and focus area for exploration.On the basis of mud logging,well logging,coring,and seismic data,the sedimentary and its evolution characteristics of Es_4~u of Shahejie Formation in Qingdong Sag were studied.The study result revealed that there existed three source-sediment systems,such as the Kendong uplift source and the nearshore subaqueous fans sedimentary systems in the north,the Qingtuozi uplift source and fan-delta,beach-bar sedimentary systems in the west and the Weibei uplift source and delta sedimentary systems in the south-east.The sedimentary systems were mainly controlled by palaeo-topography and the fault movements.The paleo-topography of surrounding uplifts and juxtaposition of horsts and depression resulted in the existence of multiple source-sediment systems.The spatial distribution of sedimentary system was controlled by faulted trenches,faulted slopes and changes of sedimentary center created by the movements of NNE,near EW and NWW fault systems.The main part of the sag is a near EW distributed sedimentary pattern,while a NE sedimentary pattern in the east is controlled by the Tanlu Fault Belt.