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基于双程波动方程的叠前逆时偏移方法成像精度高,而且无地层倾角限制,较适合于复杂地下构造成像.但是,由于地下介质的各向异性广泛存在,基于各向同性的正演算法,尚难准确描述真实的地下波场传播,逆时偏移的成像精度也因此受到限制.鉴于此,本文研究了各向异性VTI介质逆时偏移方法,首先根据VTI介质一阶准P波方程推导出了炮点和检波点的逆时延拓的交错网格高阶差分格式,针对算法计算量和存储量大的问题,文中研究了一种改进的基于GPU加速的有效PML边界存储策略.本文建议的方法只需增加少量的额外计算,就可降低大幅度的存储成本,进而实现高精度和高效率的各向异性逆时偏移.Hess 2DVTI模型测试表明,本文提出的方法不需要存储全部历史时刻的波场,可以实现高效率高精度的VTI介质叠前逆时偏移成像.
The prestack inverse time migration method based on the two-way wave equation has the advantages of high imaging precision and no restriction of dip angle, which is more suitable for complex subsurface imaging. However, due to the widespread anisotropy of underground media, Method, it is difficult to accurately describe the real underground wavefield propagation, and the imaging precision of inverse time migration is limited.Therefore, this paper studies the reverse-time migration method of anisotropic VTI media, Wave equations, the staggered-grid high-order difference scheme for the inverse time delay of shot and detection points is deduced. In view of the large amount of computation and storage, the paper studies an improved GPU-accelerated PML boundary memory Strategy proposed in this paper with only a small amount of additional calculations can reduce the substantial storage costs, and thus achieve high precision and high efficiency anisotropic reverse migration.Hess 2DVTI model tests show that the proposed method does not It is necessary to store the wave field of all the historical moments and realize the high-efficiency and high-precision prestack reverse-time migration imaging of the VTI medium.