论文详情
具有各向异性特征的复杂地下介质对地震反演结果的横向连续性与纵向分辨率造成了一定影响, 降低了反演的精度和稳定性。为此, 通过各向异性参数模型的先验概率分布分析, 阐述了地震非线性反演中Markov随机域(MRF)所呈现的各向异性特性及对反演结果的影响, 并且提出了基于各向异性扩散法的各向异性MRF及相应的叠前非线性反演方法。其数值试算结果表明, 相对于常规MRF, 各向异性MRF能够精确地搜索到待反演值。此外, 建立了扩散因子及辅助模型的优选方案, 提升了各向异性MRF方位校正系数的准确性。合成数据测试与实际资料反演结果显示, 对于纵波速度、密度和纵横波速度比的同步反演, 各向异性MRF对结果的横向连续性和纵向分辨率有明显改善; 随着扩散因子增大, 边界特征在各个方位的校正系数上体现更为明显。反演结果与测井曲线的验证对比基本吻合。
The anisotropic characteristics of spatial distribution in complex subsurface media can affect the lateral continuity and vertical resolution of seismic inversion results, thereby reducing the accuracy and stability of the inversion.Thus, the anisotropic properties of the Markov random field (MRF) in seismic nonlinear inversion and their influence on the inversion results were illustrated through an analysis of prior probability distribution of the anisotropic parameter models.An anisotropic MRF based on the anisotropic diffusion and the corresponding pre-stack nonlinear inversion method were proposed.The numerical results showed that the anisotropic MRF can accurately search for the inversion value compared with the conventional MRF.Furthermore, preferred methods for determining the diffusion factors and auxiliary models were established to improve the accuracy of orientation correction coefficients of anisotropic MRF.The results of synthetic data testing and actual data inversion showed that for the simultaneous inversion of p-wave velocity, density, and ratio of p-and s-wave velocities, the anisotropic MRF method significantly improved the lateral continuity and vertical resolution of the inversion results, and the boundary features became more obvious in the correction coefficients of each orientation as the diffusion factor increased.The inversion results were generally in agreement with the validation of the logging curves.