The second and third members of the Qingshankou Formation are believed to be the targets of petroleum exploration in the Yingtai region. The integration of cores and well logs data shows that second and third members of the Qingshankou Formation represent an overall coarsening-upward depositional sequence and/or a slowly falling phase of lake levels. The second and third members of the Qingshankou Formation may be divided into 2 third-order sequences, 4 systems tracts, 5 parasequence sets and 16 parasequences. Two sedimentary systems have been recognized, i. e. delta and lacustrine sedimentary systems. There are two sources of sediment supply from the west and north, respectively, of which the western source of sediment supply plays a major role and leads to the zonal distribution of sedimentary facies. The sandstones are overlain in bands upon the mudstones, and thus have provided the conditions to form lithologic oil pools.%青山口组二、三段是英台地区油气的重点勘探层位.综合岩芯、录井和测井等资料的研究表明,青二、三段整体上为一个反旋回,青二段沉积时期到青三段沉积时期是一个湖水水位缓慢下降的过程.英台地区青二、三段可划分为两个三级层序,4个体系域,5个准层序组,共16个准层序.青二、三段沉积时期,英台地区受到西部和北部两个物源的共同作用,主要发育三角洲沉积体系和湖泊沉积体系.
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