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棱柱波的特点是它有三段主要反射路径和两个反射点,一个反射点位于反射界面上,另一个位于陡倾角反射层上。从而含有了很多一次波无法获取的地下高陡反射界面信息,我们应用Born近似对常规逆时偏移成像剖面处理可以将棱柱波信息提取出来,然后用棱柱波进行速度更新以提高盐体悬伸侧翼等高陡构造的反演速度。基于此想法下提出了棱柱波形反演(prismatic waveform inversion),简称PWI方法,但棱柱波形反演方法存在明显的弱点:一次迭代的时间是全波形反演(FWI)的两倍,而且不能充分利用全波场信息。为此,我们将全波形反演与棱柱波形反演方法两者结合起来进行联合反演,FWI与PWI方法交替使用更新速度场。模型的试算表明,这种联合反演方法对初始模型中高陡构造信息是否缺失依赖性较低,对高陡构造的反演精度和效率都更高。
Prism waves are characterized by three main reflection paths and two reflection points, one on the reflection interface and the other on the steeply reflective layer. Which contains a lot of primary high-steep reflections of the underground interface can not get the information, we use the Born approximation for conventional RTM imaging profile processing prism information can be extracted, and then use the prism wave velocity update to improve salt overhang Back-steep contour steep structure inversion speed. Based on this idea, a prismatic waveform inversion (referred to as PWI method) has been proposed, but the prism waveform inversion method has obvious weaknesses: the time of one iteration is twice that of full waveform inversion (FWI) and can not be sufficient Use full wavefield information. To this end, we combine both the full waveform inversion and the prism waveform inversion method for joint inversion, and the FWI and PWI methods alternately use the updated velocity field. The trial calculation of the model shows that this joint inversion method has less dependence on the lack of high and steep tectonic information in the initial model and higher accuracy and efficiency of inversion for steep structures.