基于互相关误差泛函的最小二乘逆时偏移方法

最小二乘偏移可以得到成像质量更高的剖面,有利于更好地进行岩性储层成像和储层参数反演。但是,最小二乘偏移在实用化过程中却很难实现其高精度岩性成像的目标。在分析传统的最小二乘偏移存在的问题后,发展了一种基于相位匹配的最小二乘偏移方法,该方法舍弃了传统的二次型泛函,采用互相关泛函,更多地强调相位信息在最小二乘偏移中的作用,在理论上可以更好地适用于实际资料。通过对互相关误差泛函构建、逆时反偏移合成预测数据、梯度预条件处理、共轭梯度法迭代求解等方面进行研究,探索实现了基于互相关误差泛函的最小二乘逆时偏移方法。简单凹陷模型和复杂salt模型测试表明,本文方法具有较好的适用性和有效性。

A cross-correlation objective function for least-squares reverse migration

The least?square migration methods can make the seismic profile imaging quality higher,and are conducive to better imaging for lithologic reservoir and reservoir parameter inversion. However, in the process of practical application, it is very difficult for least square migration to achieve high accuracy of lithology imaging. Based on an analysis of the problems existing in the traditional least squares migration,the authors have developed a least squares migration method based on phase matching,which abandons the quadratic function used frequently by the traditional methods,and employs the cross?correlation function;in this way,this method emphasizes more on the role of the seismic phase information in the least squares inversion imaging;in theory,and it can be better applied to real data. Based on the cross?correlation function building, synthesizing prediction data by reverse time demigration, gradient precondition, and pre?conditional conjugate gradient,the authors explored and realized a cross?correlation objective function for least?squares reverse mi?gration.Simple sub?sag model and complex salt model tests show that the proposed method has applicability and effectiveness.