【摘要】 为了提高叠前偏移的计算效率并保持成像精度,此文以偏移原理为研究对象。在适当减少频率使用可以提高偏移效率的基础上,根据Hessian矩阵是非奇异的,得出了能够避免图像中出现绕射假频的频率采样方法。采样点的选取根据速度、偏移深度和偏移距的不同而不同,不仅减少了频率而且使用了有效的频率集。然后以傅里叶有限差分法为试验方法,用两个数值模型进行偏移试算,通过成像精度及运算时间证明了该频率采样方法的正确性和有效性。更多还原

【Abstract】 In order to improve the computational efficiency of pre-stack migration and maintain the imaging accuracy, this paper takes the migration principle as the research object. On the basis that migration efficiency can be improved by appropriate reduction of frequency usage, the frequency sampling method which can avoid the wrap-around artefacts in the image is obtained according to Hessian theory that matrix is nonsingular. The sampling points are selected differently according to the velocity, depth of the migration and offset, which not only reduces the frequency but also uses a subset of the effective frequencies. The Fourier finite difference method is used as an experimental method in this paper, in which two numerical models are used for migration trial calculation, and the correctness and validity of this frequency sampling method are proved by imaging accuracy and operation time.更多还原