VSP资料钻前预测的关键在于高精度的波阻抗反演,本文针对VSP资料高分辨率、高信噪比以及能精确地分离出上、下行波的特点,提出了一种利用VSP资料进行井底以下钻头前方地层波阻抗反演的方法。该方法首先对VSP走廊叠加记录采用非线性迭代反演方法反演地下地层的波阻抗;通过在迭代过程中不断修改阻尼因子,以及引入预条件共轭梯度法求解方程组,增强了解的稳定性和收敛速度。理论模型与实际资料的处理结果表明该方法具有较好的效果,并在VSP资料钻前预测研究中具有良好的应用前景。 The key point of VSP data pre-drilling prediction is high-precision wave impedance inversion. In this paper, according to the high resolution of VSP data, high signal-to-noise ratio and the ability to accurately separate the up and down waves, a VSP data well Method for inversion of formation wave impedance in front of bottom bit. Firstly, the wave impedance of underground formation is retrieved by nonlinear iterative inversion of VSP corridor overlay records. The stability of the solution is improved by continuously modifying the damping factor and introducing the preconditioned conjugate gradient method to solve the equations. And convergence speed. The theoretical model and actual data processing results show that the method has good effect and has good application prospects in the pre-drilling prediction of VSP data.