基于地震照明、面向勘探目标的三维观测系统优化设计

Target-oriented 3D seismic optimal geometry design based on seismic illumination

基于水平层状介质假设的常规三维地震勘探观测系统设计方法难以适应复杂构造区。本文利用地震照明技术,参考前人对二维问题的研究成果,发展了面向勘探目标成像的三维地震勘探观测系统优化设计方法。该方法利用三维单程傅里叶有限差分波场传播算子将勘探目的层的平面源延拓到地表,通过分析从目的层延拓到地表的地震照明能量分布,确定面向勘探目标的最佳激发范围。利用该方法可明显提高照明阴影区的照明强度,进而改善地下阴影区的成像质量。基于三维SEG-EAGE盐丘模型的地震照明与偏移成像试验结果,验证了本文面向勘探目标的三维地震观测系统优化设计方法的有效性与正确性。

Conventional methods of 3D seismic geometry design are based on the assumption of horizontal subsurface reflectors,which is not suitable for complex structure.Based on the previous research on two-dimensional problem,this paper develops a 3D target-oriented optimal geometry design method using the seismic illumination.This method uses the one-way Fourier finite-difference wave propagator to extrapolate plane wave sources from the target layer to the surface.By analyzing the wave energy distribution at the surface extrapolated from the target layer,the optimal shot positions for the target best illuminated can be determined.And finally,the imaging quality of the target or the shadow areas can be improved.In the numerical tests,seismic illumination and migration results based on the 3D SEG-EAGE salt model suggest that this 3D optimal geometry design method is effective and available.