Elastic reverse time migration using acoustic propagators

被引:0
作者
Elita Li Y. [1 ]
Du Y. [1 ]
Yang J. [1 ]
Cheng A. [1 ]
Fang X. [2 ]
机构
[1] National University of Singapore, Department of Civil and Environmental Engineering
[2] Southern University of Science and Technology, Department of Earth and Space Sciences, Shenzhen
基金
中国国家自然科学基金;
关键词
Acoustic; Elastic; Imaging; Multicomponent; Reverse time migration;
D O I
10.1190/geo2017-0687.1
中图分类号
学科分类号
摘要
Elastic wave imaging has been a significant challenge in the exploration industry due to the complexities in wave physics and numerical implementation. We have separated the governing equations for P- and S-wave propagation without the assumptions of homogeneous Lamé parameters to capture the mode conversion between the two body waves in an isotropic, constant-density medium. The resulting set of two coupled second-order equations for P- and S-potentials clearly demonstrates that mode conversion only occurs at the discontinuities of the shear modulus. Applying the Born approximation to the new equations, we derive the PP, PS, SP, and SS imaging conditions from the first gradients of waveform matching objective functions. The resulting images are consistent with the physical perturbations of the elastic parameters, and, hence, they are automatically free of the polarity reversal artifacts in the converted images. When implementing elastic reverse time migration (RTM), we find that scalar wave equations can be used to back propagate the recorded P-potential, as well as individual components in the vector field of the S-potential. Compared with conventional elastic RTM, the proposed elastic RTM implementation using acoustic propagators not only simplifies the imaging condition, it but also reduces the computational cost and the artifacts in the images. We have determined the accuracy of our method using 2D and 3D numerical examples. © 2018 Society of Exploration Geophysicists.
引用
收藏
页码:S399 / S408
页数:9
相关论文
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