基于双相介质弹性波波场分离的逆时偏移方法  

Pure compressional wave reverse time migration method based on elastic wave field separation in two-phase media

作　　者：王鸣谦 张胜寒 张济东 付继有 WANG Mingqian;ZHANG Shenghan;ZHANG Jidong;FU Jiyou(SINOPEC Geophysical Research Institute,Nanjing 211103,China;Petrochina changqing Oilfield shale Oil Oevelipment Branch,Gansu 745000,China)

机构地区：[1]中国石油化工股份有限公司石油物探技术研究院,南京211103 [2]中国石油长庆油田页油岩开发分公司,甘肃745000

出　　处：《物探化探计算技术》2023年第1期1-7,共7页Computing Techniques For Geophysical and Geochemical Exploration

基　　金：国家自然科学基金创业创新发展联合基金(U19B603)。

摘　　要：随着地震勘探的发展,以单相介质模型为基础的声波逆时偏移和弹性波逆时偏移很难比较精确地描述地下介质和满足复杂的工程要求,尤其是在处理地下含流体多孔介质时,所以需要引入双相介质模型。首先基于Biot理论双相介质一阶速度-应力弹性波方程,利用散度场和旋度场的波场分离理论将固相和流相中的纵横波场解耦分离,并由波场快照图得出固相与流相中的纵波波场与横波波场均完成分离,而快纵波与慢纵波相互耦合均存在于纵波波场中。采用高阶交错网格有限差分方法,结合PML吸收边界条件,推导了具有波场分离的双相介质弹性波正传与反传的偏移延拓算子,结合互相关成像条件,可以得到双相介质弹性波固相与流相中的各分量偏移成像剖面。最后对模型使用该双相介质弹性波波场分离的逆时偏移方法进行偏移成像试算并取得成功,效果较常规双相介质弹性波逆时偏移成像效果有了明显提升。With the development of seismic exploration,acoustic reverse-time migration,and elastic wave reverse-time migration based on the single-phase medium model is difficult to describe the underground medium accurately and meet the complex engineering requirements,especially when dealing with underground contaminants.When the fluid is a porous medium,it is necessary to introduce a two-phase medium model.Based on Biot theory,this paper first derives the first-order velocity-stress elastic wave equation of two-phase media.Then,the wave field separation theory of divergence and curl fields are used to decouple and separate the vertical and horizontal wave fields in the solid and fluid phases.The field snapshot shows that the longitudinal wave field and the transverse wave field in the solid phase and the fluid phase are separated.The coupling between the fast longitudinal wave and the slow longitudinal wave exists in the longitudinal wave field.Using the high-order staggered finite grid difference method,combined with the PML absorbing boundary conditions,the migration continuation operator for the forward and reverse propagation of the two-phase media elastic wave with wave field separation is derived.Combined with the cross-correlation imaging conditions,the offset imaging profile of each component in the solid phase and the fluid phase of the two-phase medium elastic wave can be obtained.Finally,the model uses the reverse time migration method of elastic wavefield separation in the two-phase medium to conduct migration imaging trial calculations and obtain success.Compared with conventional two-phase media elastic wave reverse time migration imaging effect has been significantly improved.

关 键 词：BIOT理论 双相介质 波场分离 弹性波逆时偏移 

分 类 号：P631.4[天文地球—地质矿产勘探]