各向异性弹性波高阶有限差分法叠前逆时深度偏移

Anisotropic elastic wave pre-stack reverse-time depth migration with high-order finite-difference scheme

采用高阶交错网格有限差分法算子构建了各向异性介质多分量弹性波动方程的高精度正演模拟和叠前逆时深度偏移的数值离散方程,在正演过程中采用最大绝对振幅能量法实现各向异性介质多分量初至旅行时的计算,并以此作为多分量双程弹性波叠前逆时成像条件,同时给出计算所需的稳定性条件、多分量叠前逆时成像的基本原理、吸收边界条件等,采用凹陷模型合成了共炮点道集,并进行多分量双程各向异性弹性波叠前逆时成像研究,并与对正演炮集进行多分量各向同性叠前逆时成像结果进行对比。计算结果表明,考虑了各向异性弹性波场的矢量特性,能够更为准确地实现叠前多分量弹性波场的成像问题,使地质层位中的断层、断点等复杂目标成像更加清晰准确,并且偏移成像精度较高,因此开展各向异性叠前逆时成像可为当前高精度岩性地震勘探提供方法指导。

The paper applied high-order staggered-grid finite difference algorithm to obtain the discrete equations of seismic wave high-precision numerical simulation and anisotropic elastic wave equation pre-stack reverse-time depth migration, adopted minimum travel-time tree algorithm to compute the first arrival travel-time,gave the method’s stable condition,reverse time imaging theory,absorbing boundary condition and so on,and create common shot gather on depressed model,then do pre-stack reverse time depth migration research and isotropic elastic pre-stack reverse time depth migration.The imaging results show that paper’s method can better achieve correct image of the multi-component elastic wave by considering the vector property of anisotropic elastic wave,especially the targets in complex geologic position such as the faults,fault points and so on,the numerical processing precision of theoretical seismic data is good,however,the results with isotropic elastic pre-stack reverse time depth migration had major error,thus this method can be an high-precision depth domain imaging method.