波动方程偏移速度建模:一种直接反演方法

基于炮域波动方程叠前深度偏移所产出的角道集,发展了不需要多次迭代的波动方程偏移速度建模方法.文中分析了炮域波动方程偏移生成角道集的方法,给出了非均匀介质中角道集同相轴曲率与速度误差的定量关系,发展了基于同相轴曲率的速度模型直接更新算法.在初始模型较合理的情况下,应用一次炮域波动方程偏移计算,即可得到较准确的速度模型.这...

Wave equation based migration velocity estimation: a direct inversion approach

We present a non-iterative velocity estimation scheme using the angle gathers resulting from the shot-profile wave equation based pre-stack depth migration. The paper discusses how to generate the angle gathers using shot-profile wave equation based migrations. A quantitative relationship between the curvature of the events in the angle gathers and the velocity perturbations in heterogeneous media is presented. As a result, we propose a direct scheme of velocity model updating based on the curvature of the events in the angle gathers. In the case that a reasonable velocity model is available, we can get a more accurate velocity model with a time shot-profile wave equation migration. This approach can overcome the problem that the velocity model obtained using the travel time tomography does not match the wave equation migration algorithm. Also, the resulting scheme avoids multiple computations of wave equation migrations, as in the current migration velocity estimation. Numerical examples demonstrate the effectiveness of the scheme.