时间剖面上的假构造及其解决方法

摘要

False structure (or structure high point migration) on seismic sections is a problem which always perplexes the seismic interpreters. In this paper the authors conducted several case studies and believed that the false structure (or structure high point migration) always exist on seismic sections in some certain circumstances, for example, when salt domes, regional igneous bodies, lower blocks of reverse fault, steep upper layers or rapid thickness change of upper layer exist in upper layer, the false structure can often be found in the lower layers. As the false structures always exist on seismic sections and they are hardly avoided in seismic data processing, the authors believe that the pre-stack depth migration (PSDM) is an ideal tool to solve the problem, however in some circumstances where PSDM can not be done, the authors then suggest to try to obtain best possible processing results through variable velocity time-depth conversion which is based on the accurate velocity field.%时间剖面上的假构造(或构造高点偏移)现象一直是困扰解释人员的一个问题.本文通过几个实例说明时间剖面上假构造(或构造高点偏移)现象的普遍性,指出在盐丘、局部火成岩体、逆掩断层下盘、上覆地层倾角较陡或上覆地层厚度剧变等情况下,都会在时间剖面上引起下伏地层出现构造变形或构造假象.针对时间剖面上构造假象的普遍性及其在时域数据处理中的不可避免性,笔者认为叠前深度偏移技术是解决时间剖面上构造假象的最佳途径;在不具备进行叠前深度偏移条件的情况下,也可在建立正确速度场的基础上通过变速时深转换实现成图.