中文摘要：

Kirchhoff偏移和逆时偏移（RTM）是目前最广泛应用的两种叠前深度偏移方法.两种方法的基础均为波动方程,理论上没有倾角限制.抽取的共成像点道集（CIG）可用于速度建模、叠前反演以及地下属性解释等.叠前反演的精度依赖于共成像点道集的AVO特性是否符合地下介质的真实地震响应.因此,叠前偏移不仅要实现反射点的准确归位,得到的共成像点道集必须要振幅保真.本文在理论上阐述两种偏移方法的基本原理,并对抽道集技术的保幅性进行对比.Marmousi和Sigsbee2a模型结果表明：在简单构造区,两者的成像效果相当;在复杂构造区,不论在成像精度还是保幅性上逆时偏移都比Kirchhoff偏移优越,特别是高陡倾角断层、岩下构造等复杂构造成像时.然而,在碳酸盐岩储层实际资料处理时发现,由于速度场准确性的限制,两种偏移方法各有优势.因此,在实际应用时,由于无法明确得到地下介质的确切信息,较难对两种偏移方法给出明确的优劣评价.

英文摘要：

Kirchhoff and reverse time migrations are two of the most widely used methods for pre-stack depth migration. Both methods are based on the wave equation, with no dip limitation. Common Imaging gathers （CIG） which are extracted from those methods can be used to velocity modeling, pre-stack inversion, subsurface attribute interpretation and so on. The inversion accuracy relies on the amplitude behavior of common imaging gathers. Therefore, Pre-stack migration should not only image the location of reflectors correctly, but also need to preserve the amplitude of CIG. This paper describe the theory of Kirchhoff migration and RTM, and analyze the amplitude behavior on the CIG gathers. The migration and CIG results from the Marmousi and Sigsbee2a model data demonstrate：in simple structure area, the imaging behavior of reverse-time and Kirchhoff migration can be comparable; in complex structure area, reverse-time migration is more accurate than Kirchhoff migration on imaging precision and amplitude behavior, especially dealing with the steeply dipping faults, subsalt et al. However, in the application to the carbonate reservoir real data, because of the limitation of the velocity model, both the Kirchhoff and the reverse-time migration methods has its own advantages individually. Therefore, in the real data processing, it will be relatively difficult to identify which method performs better because we never know the exact answer of the subsurface.