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基于反演思想的最小二乘类偏移方法,具有较常规方法更好的成像保幅性和振幅均衡性,逐渐成为研究的热点.本文将单平方根分步傅里叶反偏移算子和偏移算子引入最小二乘框架,实现了基于单平方根算子的叠前最小二乘分步傅里叶偏移(SSR-LSSSF)算法.同时,为了抑制离散傅里叶变换引起的周期性伪波场,在偏移算法中引入了余弦衰减边界.在实现优化算法的基础上,通过对复杂盐丘模型的成像试处理及与其他方法成像对比可知:(1)本文发展的SSR-LSSSF偏移方法具有较好的迭代收敛特性,成像具有较好的保幅性,成像结果逐渐逼近真实反射系数.(2)通过与RTM、LSRTM及传统SSF偏移方法成像结果对比,表明本文方法在成像精度和偏移噪声压制方面具有一定的优势.
The least-squares class migration method based on inversion idea has the better image preserving and amplitude equalization than the conventional methods, and has become a hot research topic gradually.In this paper, the single square root square-step Fourier inverse migration operator and The shift operator is introduced into the least squares framework to realize the prestack least squares fractional Fourier transform (SSR-LSSSF) algorithm based on single square root operator.Meanwhile, in order to restrain the periodicity caused by discrete Fourier transform Pseudo-wave field, the cosine attenuation boundary is introduced in the migration algorithm.On the basis of the optimization algorithm, the imaging trial of the complex salt dome model and comparison with other methods show that: (1) The developed SSR-LSSSF Compared with the RTM, LSRTM and traditional SSF migration methods, the imaging results show that the proposed method is close to the true reflection coefficient. Imaging accuracy and offset noise suppression has some advantages.