海底地层回波数据的波场外推法成像处理

Imaging the echo data of submarine sediment layers using wavefield extrapolation

海底地层回波数据的成像处理是依据地层剖面仪在海面激发以及水听器接收到的海底地层声纳回波信息来研究海底地层沉积结构的一种方法。文中运用描述声波场传播规律的波动方程将海面观测回波场记录进行反向外推处理，并指出在均匀介质或水平层状介质情况下时间成像方法的合理性，以及在沉积层构造复杂时，应同时进行绕射波场的收敛和由于介质速度横向变化引起的折射效应的时移校正的深度成像处理，从而获取准确的海底地层的结构形态。

The method of imaging the submarine sediment layers' echo data is to study the geologic structure with the information simulated by a profiler and received by hydrophone streamers at the sea surface.In this paper, acoustic wave equation, which describes the acoustic waves propagation, is used to backward extrapolate the observed echo wavefield. When the medium is homogeneous or horizontal layered, time imaging method is valid. But when the structure is complicated, the diffraction term is collapsed and the thin lens' term caused by the lateral velocity variations is time shifted as the wavefield is downward continued. Such a method, called depth imaging, can provide a good image to determine the sea-bed sediment layers.