Pure quasi-P wave stable simulation in complex TTI media
Hu Shuhua1, Wang Yuchao1, Liu Wenqing1, Zhou Yang2
1. Northwest Branch, Research Institute of Petroleum Exploration & Development, PetroChina, Lanzhou, Gansu 730020, China; 2. Wave Phenomena and Inversion Imaging Group, School of Ocean and Earth Science, Tongji University, Shanghai 210092, China
Abstract：Facing to more complicated targets, seismic exploration drops on an increasing demand for accurate subsurface imaging.We analyse the dispersion features of the decomposed scalar operator and elliptic differential operator produced by elliptic pseudo differential decomposition method proposed by Xu et al (2015).Then the corresponding first-order differential equation of pure quasi-P wave for tilted transverse isotropic (TTI) media is derived by introducing self-adjoint operators under rotated coordinates to preserve stability.Under the Lebedev staggered grid framework, we deduce the high-order finite difference scheme of the equation and give out the strategy of 2 times calculation of wavefield gradient to preserve the simulating accuracy.We test our algorithm in homogeneous and complex TTI media.The results show that the quasi-P wavefiled is not affected by pseudo-S-waves.Compared with other quasi-P wave simulating methods, our solution produces more stable wavefield in complex anisotropic media which shows that it has a high tolerance to the spatial variation of anisotropic parameters, especially the abrupt changes of the TTI symmetric axis.Our solution can be used for accurate pure quasi-P wave reverse time migration (RTM) to improve the imaging accuracy of subsurface with complex anisotropy.
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