基于共散射点道集的多次波压制方法研究

多次波压制是地震数据处理中的重要环节。一种常用的多次波压制方法是根据一次波和多次波在成像空间的曲率差异并借助Radon变换进行分离和压制。成像空间既可以是叠前时间域也可以是叠前深度域。考虑到对复杂介质的适应性以及叠前处理对计算效率的要求,提出基于共散射点(CSP)道集的高分辨率Radon变换多次波压制方法。该方法只需要一个简单的初始速度场,就可将常规共中心点道集(CMP)映射到覆盖次数更高、炮检距覆盖范围更广的共散射点道集,然后在该道集上应用高分辨率双曲Radon变换,可较好地分离一次波和多次波。相对于以水平层状介质为假设条件的CMP道集,CSP道集更适应复杂地质构造,且时距关系满足双曲规律。模型和实际资料测试结果表明,该方法可以较好地实现速度谱能量团的聚焦,有利于较复杂地质条件下的多次波压制。

Multiple elimination in common scattering gathers

Multiple elimination is a key step in seismic data processing. One of common methods is using Radon transform to attenuate multiples based on curvature difference of primaries and multiples in the image domain. The image domain can be prestack time or depth domain after migration. Considering the capability to process complex medium and efficiency required by processing approach, we propose high-resolution Radon transform based on the CSP (common scattering point) gathers to eliminate offset range. This method maps CMP gathers to CSP gathers, which have higher folds and wider offset range only using rough velocity field. In order to better eliminate multiples, we apply sparse constraints to hyperbolic Radon transform in CSP gathers, which can provide better focus of velocity spectrum. Compared with multiple elimination method in the CMP gather, the method based on CSP gather can avoid the assumption of layered media and better process complex media even under the hyperbolic trajectory. Synthetic and real data examples demonstrate that the proposed method can better focus and separate of primary and multiple waves in the velocity spectrum.