消除近地表地震散射噪音的方法

THE METHOD FOR ELIMINATING THE NEAR-SURFACE SEISMIC SCATTERED NOISE

假设近地表垂直点力产生的地震波场由入射波场和散射波场组成。散射波场由深层散射和浅层散射两个部分组成 ,若只考虑消除近地表区域的面波散射对地震资料的影响 ,则通过地震散射模型来估算近地表散射波分布。由波动理论建立近地表传播和散射模型 ,并在平行地表的一个网格面的各个节点上设置波阻抗差函数来近似地表的非均匀性。散射波场是入射波场与波阻抗差函数的函数。在这样的模式下 ,由炮集记录提取入射波场 ,进而通过最小二乘法 ,求解波阻抗差函数 ,最终得到散射波场的估计。从炮集记录中减去散射波场 。

This method assumes the seismic wave field to be composed of an incident wave field and a scattered wave field and the scattered wave field to be made of the deep scattering layer and the shallow scattering layer. Because the deep scattering layer and the shallow scattering layer have different characteristics , such as propagation time, polarized state or time of arrival, their functions are independent . If one only wants to eliminate the influence of scattering surface waves in near surface regions upon seismic data, one just needs estimating the distribution of scattered near surface waves by seismic data rather than by rebuilding the real near surface scattering body. On basis of this, from the wave theory, one can build a surface propagating and scattering model and set a function of wave impedance difference on every node of grid surface paralleling surface to approximate the surface nonhomogeneity . A scattered wave field is a function of the incident wave field and the wave impedance difference function. Under such a pattern, one can get the estimation of the scattered wave field by extracting the incident wave field by shot records and calculating the wave impedance difference function by least square algorithm. One can acquire the attenuation of the seismic scattered noise by subtracting the estimated scattered wave field from shot records.