地震波场深度外推消除与地面有关的噪音

Filtering Noise Related to Land Surface through Depth Extrapolation of Seismic Wave Field

把波场沿深度外推可以消除与地表有关的“噪音” ,如直达波、面波、声波及在表层传播的随机噪音 .波场深度外推是这种去噪方法的核心 .用全浮动坐标系的波动方程进行波场外推 ,既可避开一般双程波动方程外推时网格距选择的严格要求 ,又可克服傍轴近似方程波场外推时对波长振幅与相位的改造作用 .理论合成数据及实际炮集的处理结果表明 ,该方法不仅可滤除振幅很强、频散很严重的面波噪音 。

Wave field continuation can remove much of the energy which propagates along the surface, such as direct waves, ground roll and some random noises. The approach of wave field depth extrapolation is the key to the filtering method. In this article, we make use of the full up-ward wave equation to implement the depth filtering. There exist some advantages using the full up-ward wave equation. First, the difference equation is implicit, so it is easy to choose the grid space; second, the differential equation is accurate which may not destroy the amplitude and phase of the extrapolated wave fields.