欢喜岭地区沙三段大凌河油层近岸水下扇沉积特征

Sedimentary characteristics of the nearshore subaqueous fan of Dalinghe reservoir of Es_3 in Huanxiling area

辽河坳陷西部凹陷欢喜岭地区沙三段大凌河油层主要为一套近岸水下扇的陆相断陷湖盆沉积.根据岩性组合特征、沉积序列和测井等特征,可以划分出扇根、扇中和扇端3个亚相.对欢喜岭地区大凌河油层近岸水下扇体的沉积构造、粒度概率曲线、重矿物以及电性等特征进行了详细的分析,结果显示在扇中亚相和扇端亚相识别出扇根主河道、扇中分流水道微相、扇中水道间微相、扇中前缘微相和扇端席状砂微相5个沉积微相.受基底构造和主干断层断裂坡折带的控制,近岸水下扇在平面上具有分带性,沉积砂体平面呈扇状展布,砂体延伸较远,砂层厚度较大,沉积砂体属近源快速堆积型,垂向上由多个叠置的近岸水下扇扇体组成.

The Dalinghe reservoir of Es3 in Huanxiling area in Liaohe Depression mainly consists of a set of continental faulted lake basin deposition of nearshore subaqueous fan.According to the lithology association,the sedimentary sequence and the characteristics of well logging responses,the lake floor fan can be subdivided into three sub-facieses of fan root,fan medium and fan end.Five sedimentary micro-facieses of fan-root main channel micro-facies,fan-medium distributary channel micro-facies,fan-medium front micro-facies and fan-end sheet-sand micro-facies are recognized from fan-medium sub-facies and fan-end sub-facies based on the detailed analyses of sedimentary structures,grain size probability cumulative curve,heavy minerals and electrical properties of the reservoir.Controlled by the basement structure and the slope break belts of main faults,the plane shape of the sedimentary sand-body like a fan.Its plane area is larger and its thickness is greater.The sedimentary sand-body is the result of near-source fast depositing.In vertical direction,it is the overlay of several nearshore subaqueous fans.