孔径大小对基尔霍夫型偏移和反偏移的结果具有重要影响。对于真振幅成像,孔径不低于某个值是至关重要的。本文从理论上对偏移和反偏移的最优孔径表达式进行了推导。两种最优孔径彼此依赖,(虽然是一个时间域概念),但它在搜寻地下反射界面时,仍与依赖频率的菲涅耳带有着密切的关系。这种关系揭示了菲涅耳带在地下反射界面地震成像中新的重要作用,它表明菲涅耳带不但在分辨率研究中很重要,而且对于正确地确定偏移振幅也很重要。由此可以进一步更好地理解叠前偏移和作为同类问题的逆过程的反偏移之间存在的固有联系。通常的观点认为孔径要尽可能地大才能产生最好的信噪比。与此相反,事实上,期望找出一个最优孔径,目的是为了(a)提高计算效率和降低累积的费用;(b)基于最少道的叠加使噪声降到最小从而提高图像的质量;(c)更好地控制边界效应。本文只说明这些特性,而不去强调如何从技术上达到这个目的问题 The size of the aperture has an important influence on the Kirchhoff-type offset and backoff offset results. For true amplitude imaging, it is crucial that the aperture is not below a certain value. In this paper, the optimal aperture expressions of migration and backoff are theoretically deduced. The two optimal apertures are dependent on each other, albeit a concept of time domain, but are still closely related to frequency-dependent Fresnel zones when searching for subsurface reflection interfaces. This relationship reveals a new important role of the Fresnel zone in seismic reflection at the subsurface reflection interface. It shows that not only is the Fresnel zone important for resolution studies, but it is also important to correctly determine the amplitude of the offset. This makes it possible to further better understand the inherent relationship between prestack migration and inverse migration of the inverse process as a homogeneous problem. The general idea is that the aperture should be as large as possible to produce the best signal-to-noise ratio. In contrast, in fact, it is desirable to find an optimal aperture in order to (a) increase computational efficiency and reduce cumulative costs; (b) improve image quality by minimizing noise based on least-track overlay; c) Better control of the border effect. This article only explains these features, not to emphasize how to technically achieve this goal