西湖凹陷杭州斜坡带北段断裂系统特征及其对圈闭的控制

The Characteristics of Fault System and Its Control on Traps in the North Part of Hangzhou Slope Zone, Xihu Depression

摘要: 本文在新三维地震资料解释基础上，分析杭州斜坡带北段断裂系统特征，探讨断裂对圈闭的控制作用。研究结果表明：在斜坡结构上，杭州斜坡带受杭州35古隆起分隔影响，具有“南北分块”特征，其中北段处于古隆起东北缘，受控于迎翠轩主断裂。在断裂系统特征上，北段断裂系统在垂向上可明显的分为下部断陷构造层、中部断拗转换构造层和上部拗陷–反转构造层。在断裂控圈特征上，杭州斜坡带北段构造圈闭主要发育于断–拗转换构造层平湖组地层内，受迎翠轩主断裂活动下的NNE-NE向断裂控制，具有一定的牵引背斜形态，总体定型于平湖组沉积末期的玉泉运动时期。根据断裂及背斜组合样式，区内构造圈闭多与扭动构造样式有关，圈闭类型可划分为断鼻构造圈闭群、帚状构造圈闭群和似花状构造圈闭群。最终，本文综合区域地质条件认为，迎翠轩主断裂后期活化与大规模生烃作用匹配较好，处于迎翠轩主断裂下降盘的帚状、似花状构造圈闭易于俘获油气，是值得进一步勘探的有利目标。

Abstract: Based on the interpretation of 3D seismic data, this paper analyzes the characteristics of the fault system in the northern part of Hangzhou slope zone, and discusses the controlling effect of faults on traps. The results show that: in the slope structure, the Hangzhou slope zone is affected by the 35 ancient uplift of Hangzhou, which has the characteristics of “North-South block”. The north section which located in the northeast margin of the ancient uplift, is controlled by the main fault of Yingcuixuan. In terms of the characteristics of fault system, the northern fault system can be vertically divided into the lower fault depression structure layer, the middle fault depression transformation structure layer and the upper depression inversion structure layer. The structural traps in the northern part of Hangzhou slope zone are mainly developed in Pinghu Formation of fault depression transition structural layer, controlled by NNE-NE faults under the main fault activity of Yingcuixuan, with certain traction anticline shape, and generally formed in the Yuquan movement period at the end of Pinghu Formation deposition. According to the combination pattern of faults and anticlines, the structural traps in the area are mostly related to the twisting structural pattern. The trap types can be divided into fault nose structural trap group, broom structural trap group and flower like structural trap group. According to the comprehensive regional geological conditions, the late activation of Yingcuixuan main fault is well matched with large-scale hydrocarbon generation, and the broom like and flower like structural traps in the descending plate of Yingcuixuan main fault are easy to capture oil and gas, which are worthy of further exploration.