基于变网格的不同观测系统下的逆时偏移（英文）

Variable-grid reverse-time migration of different seismic survey data

逆时偏移被认为是处理陡倾角断层、回转波和逆掩推覆构造最有效的成像方法。考虑到当今勘探对地下复杂构造体、薄互层和隐蔽储层的高分辨率成像需求,井间、井中地震资料成为地面地震资料的一个很重要的补充。但由于地面地震、井中地震和井间地震存在很大的频率差异,本文将相应的变网格算法应用到偏移中。另外,也将Lanczos滤波引入到波场外推计算中,从而可以很好地消除变网格引起的人为反射。试算表明,对比地面、井中和井间的偏移,可以看到微构造、陡反射层都得到了更好地刻画和描述。基于变网格的逆时偏移在储层预测和岩性解释方面有广阔的应用前景。

With an increasing demand for high-resolution imaging of complex subsurface structures, thin layers and hidden reservoirs, borehole and cross-well seismic migration methods have become important. However, large differences are observed in the frequency bandwidth between the surface, borehole, and cross-well surveys. Thus, variable-grid- based algorithms have been adapted to reverse-time migration. Further, we introduce Lanczos filtering to ensure the stability of wavefield calculations as well as to decrease the artificial reflections that are caused due to the variable grid size. Finally, we observe that the application of this method to surface survey, borehole, and cross-well seismic data suggests improvements in the delineation of minor fractures and steeply dipping faults.