恩平凹陷南部斜坡断层阴影带构造恢复方法研究  

Structure restoration method study of fault shadow zone in the southern slope area of Enping depression

作　　者：宋亚民 戴朝强 张丽萍 吴成 邓勇 SONG Ya-min;DAI Chao-qiang;ZHANG Li-ping;WU Cheng;DENG Yong(Shenzhen Branch of CNOOC Limited,Shenzhen 518000,China)

机构地区：[1]中海石油(中国)有限公司深圳分公司,深圳518000

出　　处：《地球物理学进展》2020年第6期2194-2202,共9页Progress in Geophysics

基　　金：国家重点研发计划课题(2018YFC0604302);国家科技重大专项课题(2017ZX05008-004);国家自然科学基金(41772248)联合资助。

摘　　要：恩平凹陷南部斜坡带为油气富集的有利区带,沿斜坡长轴方向发育的一系列断背斜构造为该带主要的油气聚集单元.勘探开发实践表明,该带发育的断背斜构造普遍受断层阴影影响,表现为断层阴影带地震成像畸变,地层产状失真,圈闭形态及面积均难以落实.针对这一难题,从恩平南部斜坡带断层阴影带地震反射特征及实际钻探情况出发,分析了该带断层阴影带的特征及其对构造落实的影响;通过地震正演,直观揭示了断距、断层倾角、断层两盘层速度差异对断层阴影带地震成像的影响,即断距影响断层阴影带地震同相轴的畸变程度,断层倾角主要影响畸变范围,断层两盘地层速度关系影响畸变的"上拉"或"下拉"性质;结合恩平南部斜坡带地质特点,以受断层阴影影响的恩平X油田为例,通过地震正演揭示了该油田断层阴影带特征,并通过阴影带补偿校正的方法基本恢复了断层阴影带构造特征.在油田开发早期地震资料重处理过程中,充分考虑断层阴影带构造畸变对基于构造导向约束的网格层析速度反演方法构建偏移速度场精度的影响,采用断层阴影带补偿校正后的构造网格做约束对偏移速度场进行更新,有力改善了断层阴影带叠前深度偏移成像效果,进一步落实了阴影带构造形态,为储量评价及开发方案部署奠定基础.恩平凹陷南部斜坡断层阴影带构造恢复方法对类似的断层阴影带的构造研究及地震资料的精细处理均有一定借鉴意义.The southern slope zone of Enping depression is a favorable zone for oil and gas accumulation, and a series of faulted anticlinal structures along the long axis of the slope are the main oil and gas accumulation units in this zone. Exploration and development practice shows that faulted anticline structures developed in this zone are generally affected by fault shadow, which usually characterized by seismic imaging distortion and stratum occurrence distortion in fault shadows zone on seismic section, resulting in difficulty in implementing trap shape and trap area. In order to solve this problem, based on the seismic reflection characteristics and actual drilling results of fault shadow zone in Enping South slope area, the characteristics of fault shadow zone in this area and its influence on structural implementation are analyzed. The influence of fault throw, fault dip angle and formation velocity difference between upthrow and downthrow of fault on seismic imaging in fault shadow zone is revealed by seismic forward modeling. The results shows that fault distance affects the distortion degree of seismic event, fault dip mainly affects the range of distortion, and the relationship of formation velocity between upthrow and downthrow of fault affects the "pull-up" or "pull-down" nature of distortion. Based on the geological characteristics analysis of Enping depression south slope area, taking Enping X oilfield which is influenced by fault shadow as an example, firstly,we build several geological model across the fault shadow zone and carried out seismic forward modeling based on well and seismic data in order to disclose characteristics of seismic imaging distortion in fault shadow zone, and then quantitatively analyzed the degree of seismic imaging distortion and restored the structure form in fault shadow zone by correction, the predicted structural depth shows litter difference with the actual drilling result. Finally, during seismic data reprocessing in oil field early developing stage, the influence of struc

关 键 词：断层阴影 构造恢复 恩平凹陷 地震正演 阴影带补偿校正 

分 类 号：P631[天文地球—地质矿产勘探]