Most sedimentary formations with fine layers can be characterized as transversely isotropic media. The evaluation of shear-wave anisotropy is critical in logging-while-drilling (LWD) applications. We developed a joint method to simultaneously invert formation shear-wave anisotropy and vertical shear velocity using LWD monopole and dipole dispersion data. Theoretical analysis demonstrates that formation shear-wave anisotropy significantly affects the dispersion characteristics of Stoneley and formation flexural waves. The inversion objective function was constructed based on the change in dispersion characteristics and was weighted by the spectra of multipole waves. Numerical results using synthetic examples demonstrate that the joint inversion method can not only alleviate the non-uniqueness problem but also help improve the accuracy of the inversion results. The comparison of different signal-to-noise ratio inversion results proved that the weighted inversion method is more accurate and stable.

大多数具有细层的沉积地层可以表征为横向各向同性介质。剪切波各向异性的评估在随钻测井 (LWD) 应用中至关重要。我们开发了一种使用 LWD 单极子和偶极子色散数据同时反演地层剪切波各向异性和垂直剪切速度的联合方法。理论分析表明，地层横波各向异性对斯通利波和地层弯曲波的频散特性有显着影响。反演目标函数是根据频散特性的变化构造的，并由多极波的光谱加权。综合算例的数值结果表明，联合反演方法不仅可以缓解非唯一性问题，而且有助于提高反演结果的精度。不同信噪比反演结果的对比证明，加权反演方法更准确、更稳定。