频率域叠前波动方程反演及其应用

Pre-stack wave equation inversion and its application in frequency domain

基于波动方程的叠前反演是地球物理反演的重要发展方向,它利用全波场信息反演的弹性参数对预测地下储层的含油气性有重要的参考价值。本文推导了频率空间域全波形反演公式,并将波动方程写成矩阵形式,反演过程中采用波场回传技术和可控共轭梯度算法来更新模型参数。推覆体模型试算结果表明,该方法适用于速度横向变化剧烈地质体,经过几十次迭代可以收敛到真实速度模型。在我国西部某气田实际资料应用表明,反演出的弹性参数与井数据吻合较好,能够为流体识别和储层含油气性预测提供可靠的地球物理参数。

The wave equation inversion is an important development direction.Elastic parameters obtained by the inversion of the full wave field information would be very helpful in predicting oil or gas reservoirs.In this paper,we derive the full waveform inversion equation in frequency-space domain written in matrix form.The back propagation technique and controlled conjugate gradient algorithm are used to update the parameters model.The overthrust model test shows that this method is suitable for geologic body with great horizontal velocity variation.The initial model can converge the true model after dozens iterations.Applications to a gas field in western China show that the inversion parameters coincide with log data very well and can be used for fluid identification and oil-gas reservoir prediction.