基于高斯束偏移的倾角域绕射波分离方法研究

断层、缝洞体等非均质体在地震响应中主要表现为绕射波,但常规资料处理后的绕射波常被一次反射能量淹没,因此单独分离并研究这类绕射波在某种程度上可以提高非均质体识别的准确性。倾角域道集上的绕射波拟线性而反射波拟抛物线的形态差异为波场分离提供依据。利用高斯束偏移抽道集方法提取倾角域道集,并设计基于相似谱分析的波场分离方法实现倾角域道集中的绕射波分离。模型试算结果表明:运用相似谱分析方法进行波场分离后的倾角域道集中,反射能量得到压制,绕射能量得到较好保留。将波场分离后的绕射波场进行叠加成像,结合常规的全波场成像结果进行对比分析,可提高绕射目标构造的识别度。

Diffraction separation in dip-angle domain based on Gaussian beam migration

Heterogeneous objects such as faults and fracture-cave cubes cause diffractions in seismic records. After conventional seismic processing, diffractions are usually buried in one-way reflections. Separating diffractions can improve the interpretation accuracy of heterogeneous objects. Common imaging gathers (CIGs) in dip-angle domain can be used to separate wavefield, because diffractions are quasi-linear and reflections are quasi-parabolic in the CIGs. We use Gaussian beam migration to gather dip-angle domain CIGs, and separate diffraction based on semblance analysis. Model tests show that semblance analysis suppresses reflections but preserves diffractions in dip-angle domain CIGs after wavefield separation. Diffraction imaging results together with full wave imaging can thus enhance interpretation accuracy.