基于纵横波解耦的双相介质弹性波方程正演模拟及结果分析  

Forward modeling and analysis of elastic wave in dual-phase isotropic media base on P-wave and S-wave decoupling

作　　者：王玉凤[1] 何兵寿[1] 张省[1] 

机构地区：[1]中国海洋大学海底科学与探测技术教育部重点实验室,青岛266100

出　　处：《地球物理学进展》2013年第6期3030-3039,共10页Progress in Geophysics

基　　金：国家自然科学基金项目(41204089;40804021;41174087);国家自然科学重点基金项目(40839901);国家油气重大专项项目(011ZX05005-005);127专项(GZH201100307)联合资助

摘　　要：纵横波联合探测可以获得丰富的地下结构信息.本文从各向同性介质Biot方程出发,推导基于纵横波解耦的高阶有限差分算子,给出其最佳匹配层(PML)吸收边界条件及稳定条件,在此基础上实现双相各项同性介质中弹性波数值模拟及纵横波解耦.对双层模型及含天然气水合物沉积地层模型进行数值模拟,模拟结果证实:在交错网格空间中,该算法能有效模拟地震波在双相弹性介质中的传播,得到高精度的纯纵波、纯横波波场快照与合成记录.分析解耦的纵横波,可以认识到:快、慢纵波因相互伴生而无法实现分离,且归属于纯纵波波场.慢纵波尽管衰减得快,但被某一界面反射后,转换形成的纵波和横波仍以正常的方式传播,且比慢波衰减小.在固相、流相中的纵波分量、横波分量的记录上均能识别出BSR.The complex subsurface crustal structure can be obtained by applying the joint exploration of P-waves and S-waves. From the Biot equation in elastic isotropic medium, a high-order finite difference scheme with P-waves and S-waves decoupling was established, the corresponding perfectly matched layer （PML） absorbing boundary conditions and stability conditions were also provided, based on which a high-order finite difference numerical modeling algorithm for elastic wave equations of two-phase isotropy media was realized, and the P and S waves were decoupled. The simulation results of a two-layered model and a gas hydrate layered model show that： in the space of staggered-grid, this algorithm could effectively simulate the seismic waves＇ propagation in the dual-phase isotropic media. By analyzing the decoupled P-waves and S-waves, it was known that the fast and slow P waves were associated and could not be decoupled, they both belonged to the pure p-waves fields. Although slow waves were attenuated strongly, when they were reflected by an interface, the converted P-waves and S-waves propagate in a normal way with much less attenuation than the slow waves. BSR could be identified in both P-wave component and S-wave component of the soild phase and flow phase.

关 键 词：纵横波解耦 双相介质 Biot模型 数值模拟 天然气水合物 BSR 

分 类 号：P631.41[天文地球—地质矿产勘探]