西湖凹陷平湖斜坡带平湖组富煤地层含砂率20%~40%,寻找规模性砂体对提高勘探效益十分重要。由于平湖组处于断拗转换期,断裂活动对沉积充填与砂体展布有显著控制作用,为厘清平湖组沉积时期同沉积断裂体系所组成的构造转换带如何控砂控相,基于三维地震资料解释和钻井资料分析,开展了平湖斜坡带平湖组孔宝地区断裂构造样式、构造演化与展布、孔宝地区断裂与转换带类型和构造转换带与古地貌对砂体的控制作用研究。结果表明:平湖斜坡带可划分为孔南顺向断阶区、宝武槽垒复合区和平团陡坡近洼区,孔宝地区断裂以Ⅱ~Ⅳ级断裂与小断裂为主;构造转换带控砂模式包括断阶转换带控砂、坡折型转换带控砂以及反向断阶转换带控砂;古地貌控砂模式包括坡折带控砂、“堑式”断槽控砂和断洼控砂等。研究成果为该地区油气勘探提供了依据。

The coal-rich strata of the Pinghu Formation in the Xihu Sag exhibit a sand content ranging from 20% to 40%. Identifying large-scale sand bodies is crucial for enhancing exploration efficiency. Since the Pinghu Formation is in the fault transition period, fault activity has a significant control on sedimentary filling and sand body distribution. In order to clarify how the structural transition zone, composed of the synsedimentary fault system during the deposition of the Pinghu Formation, controls sand and facies, a study was conducted based on 3D seismic data interpretation and drilling data analysis. This study focused on the fault structure style, structural evolution and distribution in the Kongbao area of the Pinghu Formation within the Pinghu Slope Belt, as well as the types of faults and transition zones in the Kongbao area, and the control effects of structural transition zones and paleogeomorphology on sand bodies. The results show that the Pinghu Slope Zone can be divided into the Kongnan forward fault-step zone, the Baowu trough-horst complex area and the Pingtuan steep slope near-sag area. The faults in the Kongbao area are predominantly grade Ⅱ-Ⅳ faults and minor faults. The sand-controlling modes of the structural transition zone include the fault-step transition zone, the slope-break type transition zone and the reverse fault-step transition zone. The paleogeomorphological sand-controlling modes include the slope-break zone, the “grape-type” fault trough and the fault depression. These results provide a basis for oil and gas exploration in this area.