构造转换带制约下的砂体富集效应:以平湖斜坡孔雀亭区平湖组为例

Sand Enrichment Constrained by Structural Conversion Zone:the Pinghu Formation in the Kongqueting Area of the Pinghu Slope

构造转换带是油气藏勘探开发研究的重要领域,分布在多种类型的挤压或伸展盆地中。基于转换带的理论基础,认为同沉积时期其对砂体的汇聚具有显著的控制作用。平湖斜坡带孔雀亭地区平湖组处于断拗转换期,厘清该时期同沉积断裂体系所组成的构造转换带如何控砂控相,对下步勘探开发具有重要意义。基于三维地震资料解释和录井资料研究,通过构造样式、断裂体系与生长指数梳理,厘清孔雀亭地区平行、共线与叠覆三种转换带类型;同时,转换带控制洼隆相间古地貌的形成,进而控制沉积砂体在近断裂转换点且可容纳空间大的地势低洼区卸载与富集,发育形成坡积扇、前缘水下扇和复合砂坝等沉积微相。根据古地貌特征、转换带类型与沉积砂体的匹配关系,厘定挠曲型平行转换带控砂模式、雁列型共线转换带控砂模式和扭动改造型叠覆转换带控砂模式。其中,挠曲型平行转换带与雁列型共线转换带聚砂效果最为显著。论文工作为后续构造—岩性油气藏勘探提供一定经验。

Structural conversion zone is an important field of oil and gas exploration and development,which is distributed in many types of compressional or extensional basins.Based on the theories of conversion zone,it is considered that there is a significant control on sand body convergence in the Syndepositional period.The Pinghu Formation in the Kongqueting area of the Pinghu Slope records the fault-depression transition.It is of significance for further exploration and development to clarify the control on the sand and facies in the structural transformation zone composed by the synsedimentary fault system in this period.Based on the interpretation of 3D seismic data and logging data,three types of parallel,collinear and overlapping transition zones in the Kongqueting area were clarified by comprehensive analyses of structural style,fault system and growth index.The tectonic conversion zone controls the formation of the paleogeomorphology between depressions and uplifts,and further controls the unloading and enrichment of sedimentary sand bodies in low-lying areas near the fault conversion point with a large accommodation space.These sand bodies developed into sedimentary microfacies,such as deluvial fan,front underwater fan and composite sand bar.Based on the matching relationship between paleogeomorphic characteristics,transformation zone types and sedimentary sand bodies,three sand-control models of flexured-parallel transfer belt,flying-geese-like collinear transfer belt and wriggling-transformed-overlapping transfer belt were determined.The former two have good sand accumulation effects.This study provides insights into subsequent exploration of tectonic lithologic reservoirs.