【摘要】 为了充分利用地震记录中的绕射波信息刻画地下小尺度地质体(断层、裂缝、尖灭和孔洞等),需要将弱能量的绕射波从地震全波场中分离出来以实现绕射波单独成像。为此,在倾角域共成像点道集(CIGs)中,根据绕射波与反射波同相轴的形态差异,提出一种基于迭代收缩高分辨率Radon变换的绕射波分离与成像方法。首先采用迭代收缩阈值算法(ISTA),通过时间域简单的模型收缩步骤获得Radon域模型的稀疏性,以解决常规Radon变换中反射波与绕射波在Radon域中能量团聚焦性差、绕射波场分离效果不理想的问题;其次在编程实现算法的基础上,通过模型数据验证了该方法可有效分离绕射波、抗噪能力强,且当迭代超过20次时计算效率约为常规迭代重加权最小二乘(IRLS)算法的两倍。实际地震资料的应用验证了该方法具有较好的适用性。更多还原

【Abstract】 In order to make full use of the diffractions in seismic record to describe small underground structures(faults,fractures,holes,etc.),it is necessary to separate weak diffractions from seismic full-wave field and image diffractions separately.In dip-angle common imaging point gathers(CIGs),a separating and imaging method of diffractions based on high-resolution Radon transform on an iterative model shrinking approach is proposed.This method considers the morphological difference in diffracted and reflected events.It uses an iterative shrinkage threshold algorithm(ISTA)to obtain the sparsity of Radon model through model shrinkage steps in time domain and solve the problem that the separated effect of diffraction wave field caused by poor focusing of reflection and diffraction energy group is not ideal in conventional Radon transform.On the basis of programming algorithm,the method can effectively separate diffracted waves and has strong anti-noise ability on model data.On real data,the computing efficiency of the method is about twice than that of the conventional IRLS at more than 20 iterations,proving it applicable for real seismic data.更多还原