垂直地震剖面资料波动方程反演用于井底以下地层预测

Vertical Seismic Profiling for Predicting Layers below Well Bottom

利用垂直地震剖面 (VSP)资料波场可分离的特点 ,以下行波作震源函数 ,上行波作约束进行一维波动方程迭代反演 ,同时给出了一种快速生成梯度矩阵的近似算法 .通过选取反射系数作反演参数 ,改良了方程组的性态 ;通过适当加入阻尼因子 ,增强了求解的稳定性和抗噪音能力 .该法适用于井底以下地层的预测以及随钻反演 .实际资料的算例结果表明 。

VSP(vertical seismic profiling) data are used in conjunction with a one dimensional wave equation inverse method. Downward wave may be regarded as source function and upward wave as restriction. An algorithm is developed for fast creating gradient matrix. To improve the quality of equation group, reflectance is chosen as the inverse parameter. Moreover, the stability and degree of noise resistant were increased by introducing a damping factor. Layers below the well bottom can be predicted in addition to SWD(seismic while drilling)inversion.