【摘要】 在Thomsen精确相速度方程和弱各向异性假设前提下,将VTI相速度方程拓展为TTI介质相速度方程,进而得到TTI介质的P波方程。利用伪谱算法对P波方程进行了正演和逆时偏移,并和各向同性F-X域深度偏移效果进行了对比,结果表明:①对于各向异性介质,利用各向同性的偏移算法得到的结果会有误差,成像结果有明显的畸变;②在考虑效率和精度的前提下,伪谱法由于其利用快速二维傅里叶变换解决空间导数的计算问题,这对于实际应用中计算成本颇高的逆时偏移是一个较理想的选择;③推导的近似方程在弱各向异性条件下可以较好地应用于TTI介质中。更多还原

【Abstract】 Based on Thomsen’s accurate phase velocity formula and weak anisotropic assumption,an approximate phase velocity formula in TTI media is derived in this paper by expanding the phase velocity formula in VTI media.Using this approximate phase velocity formula to wave equation,P-wave equation is derived.Pseudo-spectral method is employed to forward simulating and reverse-time migration(RTM).Comparing isotropic pre-stack depth migration in F-X domain with RTM,the following indications are obtained: ①For anisotropic media,migration results by isotropic algorithms may have visible error,and this will cause imaging problems.②With the consideration of cost,efficiency and accuracy,it is a good idea to use pseudo-spectral method which solved the space derivative problem with FFT instead of RTM.③The approximate wave equation can be well used in TTI media on weak anisotropic assumption.更多还原