基于基追踪分解算法的薄层波阻抗反演

为提高波阻抗反演的分辨率,将基追踪反演(basis pursuit inversion,BPI)方法用于地震阻抗反演。该反演方法将地层的顶、底反射系数视为一个奇对称脉冲对和一个偶对称脉冲对的线性组合。反演过程中将地震信号通过基追踪算法投影到子波与上述两类脉冲褶积形成的楔形模型库上,通过该投影值可求得每道的相对反射系数。得到相对反射系数剖面后,进行道积分即可得到相对波阻抗剖面。相比于传统的稀疏脉冲反演(sparse spike inversion,SSI),BPI结果不受初始模型的影响,可显著提高波阻抗反演对薄层的分辨能力。对合成信号的试算表明,BPI结果比SSI结果更好地识别了薄层信息。对珠江口盆地碳酸盐岩储层的实际地震数据的反演表明,BPI结果上的很多细节信息在传统SSI结果上无法看到。因此,BPI更适用于薄层波阻抗的反演。

Impedance Inversion of Thin-Bed Based on Basis Pursuit

In order to improve the resolution of impedance inversion, we perform basis pursuit inversion (BPI) to impedance inversion. We consider the top and bottom reflectors of thin-bed as a linear combination of even and odd impulse pairs. In our inversion process, we decompose the seismic signal to the convolution of wavelet and even and odd impulse pairs by basis pursuit decomposition algorithm. We can obtain the reflection coefficient by the decomposition coefficients. BPI is not affected by initial model, which is advance to sparse spike inversion (SSI). Synthetic tests suggest that the resolution of BPI can better resolve thin beds than SSI. Application to field data indicates that BPI results can show some details that are not readily seen on SSI results. In this case, BPI is more suitable for thin beds inversion.