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在复杂地表条件的区域,地震数据的采集和处理是一项极大的挑战。虽然可以通过静校正来消除起伏地表的影响,然而当地表高程以及近地表速度剧烈变化时,简单的垂直时移对地震波场造成的畸变会严重降低偏移成像的质量。基于射线的偏移方法可以直接在起伏地表面进行波场的延拓成像,是解决上述问题的有效手段。本文针对复杂地表条件下的高斯波束叠前深度偏移进行研究,对倾斜叠加公式进行修改,使之包含地表高程以及速度的信息,通过直接在复杂地表面进行平面波的合成,得到了一种具有更高成像精度的改进方法。首先简单介绍常规高斯波束偏移的基本原理和计算流程,并以此为基础,给出复杂地表条件下高斯波束偏移原有的实现方法以及本文的改进方法,最后通过模型和实际资料的试算验证本文方法的有效性。
In the area of complex surface conditions, the collection and processing of seismic data is a great challenge. Although the effect of undulating surface can be eliminated by static correction, the distortion of seismic wavefield caused by simple vertical time-shift will seriously reduce the quality of migration imaging when the local surface elevation and the near-surface velocity change drastically. The ray-based migration method can directly carry out the continuation imaging of the wave field on the fluctuating surface, which is an effective method to solve the above problems. In this paper, we study the prestack depth migration of Gaussian beam under complicated surface conditions, modify the tilt superposition formula to include the information of surface elevation and velocity, and synthesize the plane wave directly on the complex surface, Improved method of higher imaging accuracy. First of all, the basic principle and calculation flow of conventional Gaussian beam migration are briefly introduced. Based on this, the original implementation of Gaussian beam migration under complex surface conditions and the improved method of this paper are given. Finally, the model and actual data test Calculate the effectiveness of this method.