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用CDP法来解决复杂的地质构造问题时,存在着明显的缺陷,而且,对不同炮检距资料的叠加还会破坏作地层分析所必须的振幅特性。所以,为了保存资料中的构造信息以及振幅信息,应进行叠前处理。根据共炮检距资料和界面上部的速度,叠前声波克希霍夫反演能确定界面的位置。若资料中保存有振幅信息时,还可以计算出界面上各点的反射系数。对于带限的地震资料来说,反演可得出反射界面的一种类似于绕射函数(sinc函数)的图像,这一带限奇异函数的峰值振幅等于随角度而变的反射系数。反演以在一般3-D反演算子中插入的高频克希霍夫资料为基础的。用四维稳定相位法渐近地求取四个最终积分就可以选出反演振幅函数,由此使反演算子产生与反射面有关的、用反射系数加权的奇异函数。将三维反演算子简化为2.5维反演算子就能处理单条测线的共炮检距资料。本文用合成例子说明了该反演方法对常速克希霍夫资料的精度,以及把常速资料用于多层速度模型时所存在的问题。
CDP method to solve complex geological problems, there are obvious shortcomings, but also for different offset data offset will destroy the necessary for the formation of the amplitude characteristics of the analysis. Therefore, in order to preserve the structure information and amplitude information in the data, prestack processing should be carried out. According to the common offset data and the speed of the upper part of the interface, prestack sonic Kirchhoff inversion can determine the position of the interface. If the information stored in the amplitude information, you can also calculate the interface of the reflection coefficient of each point. For band-limited seismic data, the inversion yields an image of the reflection interface similar to the diffraction function (sinc function) whose peak amplitude equals the angle-dependent reflection coefficient. Inversion is based on high-frequency Kirchhoff data inserted in a general 3-D inversion operator. The inverse amplitude function can be chosen by asymptotically finding the four final integrals using the four-dimensional steady-phase method, thereby enabling the inversion operator to produce singular functions that are weighted with reflection coefficients that are related to the reflecting surface. By simplifying the three-dimensional inversion operator into a 2.5-dimensional inversion operator, the common offset data of a single line can be processed. In this paper, the synthesis example is used to illustrate the accuracy of the inversion method for the constant velocity Kirchhoff data and the problems existing when applying the constant velocity data to the multi-velocity model.