三维波动方程全倾角偏移

3-D Wave Equation All-Dip Migration

三维波动方程全倾角偏移成像法对于构造复杂和速度变化较剧烈的地震资料能获取理想的成像效果．本文利用“方向导数法”和“时间步长分裂法”，不对方程作任何近似，可将浮动坐标系下的波动方程简化成易于求解的１５°偏移方程形式．为了保持时间和空间方向满足两阶精度以及提高计算速度，在构造差分方程时运用Ｐ—Ｒ交替格式，使之局部地分裂成二维求解方程，从而实现了三维全倾偏移．理论记录和实际资料的处理都证实了该方法的正确性和高效性．

The method of 3-D wave equation single-step migration with all dip can produce a good image for the seismic data with complex styuctures and severe velocity variations. The 'direction derivation' and the 'time-step splitting' approaches discussed in this paper transverse the equation under the floating coordinates system into the form similar to the 15℃ migration equation, without any approximation to the original one. In order to preserve the second-order accuracy both in time and in space, and to speed computation, we use P-R alternative splitting scheme when constructing the difference equation, so that the 3-D full-dip migration can be realized. Synthetic data and field example are used to demonstrate the fact that this method is successful in practice.