Kelvin-Voigt黏弹性介质地震波场数值模拟与衰减特征  

NUMERICAL MODELING AND ATTENUATION CHARACTERISTICS OF SEISMIC WAVEFIELD IN KELVIN-VOIGT VISCOELASTIC MEDIA

作　　者：严红勇[1,2] 刘洋[1,2] 

机构地区：[1]中国石油大学油气资源与探测国家重点实验室,北京102249 [2]中国石油大学CNPC物探重点实验室,北京102249

出　　处：《物探与化探》2012年第5期806-812,共7页Geophysical and Geochemical Exploration

基　　金：国家"863"计划资助项目(2007AA06Z218);国家油气重大专项课题(2011ZX05019-008)

摘　　要：利用高阶交错网格有限差分模拟Kelvin-Voigt黏弹性介质中传播的地震波,同时将完全匹配层吸收边界条件引入到其边界处理中。数值模拟结果表明,完全匹配层吸收边界效果好,高阶有限差分能模拟得到的黏弹性介质波场精度较高。对模拟的黏弹性波场进行分析,表明介质的粘滞性使地震反射波的能量变弱,高频衰减明显,并比低频衰减得快,主频向低频方向移动,有效频带变窄,即降低了地震波的分辨率;并且反射转换波比反射纵波要衰减得快;而且还随着传播距离的增加,其峰值频率也逐渐降低。通过数值模拟分析具有不同的粘滞系数介质对地震波的吸收和衰减,结果表明随着粘滞系数的增大,地下介质对地震波的吸收衰减更明显。This paper uses finite difference algorithm of high-order staggered-grid simulate Kelvin-Voigt viscoelastic media of seismic waves and meanwhile introduces the perfectly matched layer（PML） absorbing boundary condition into its boundary. Numerical simula- tion demonstrates that the effect of this algorithm of absorbing boundary is very good and the wavefield of viscoelastic media obtained from high-order finite difference is relatively accurate. An analysis of viscoelastic wavefield simulation shows that the energy of the re- flected wave becomes weaker, the attenuation of the high frequency wave is much more apparent in comparison with that of the low fre- quency wave, the main frequency becomes closer to the low frequency, and the effective bandwidth is narrower, which all induce low resolution of seismic wave according to the simulation of viscoelastic wavefields. Besides, the attenuation of PS-wave is much more rap- id in comparison with that of PP-wave and the peak frequency becomes lower gradually with the increase of the propagating distance. It is also shown that the absorption and attenuation are more apparent with the increase of viscosity coefficient by analysis of the absorption and attenuation of seismic wave in different viscosity coefficient media.

关 键 词：黏弹性 交错网格 有限差分 完全匹配层 衰减 

分 类 号：P631.4[天文地球—地质矿产勘探]