采用射线寻迹的井间层析成像

本文采用二维井间观测走时反演地震波速,用迭代射线寻迹走时成像方法进行层析成像.作者导出三次多项式插值基函数计算离散网格内的折射率分布,还给出了具有自己特点的二步扫描法,不但加快了正演计算时间,同时方便地建立走时残差与模型修正量的关系.考虑到实际应用时,震源与接收器常不位于同一平面,为此进行了校正,并给出了校正方法,提高了重建精度. 数值的与实际应用的结果表明,本文给出的层析成像算法是快速的、稳定的、适用的.

CROSS-HOLES TOMOGRAPHY USING RAY TRACING

The tomographic imaging of seismic wave velocity between the cross-holes by iterative ray-tracing method using travel-time was discussed in this paper. In order to make the forward or inverse procedure stable and fast, the interpolation basis function with three orders derived by us was used to calculate the refractivity within the digital net, meanwhile, from this basis function, the relationship between the travel-time residuals and modified parameters can be established conveniently and jacobian matrix for inversion can be derived easily. The scanning method with its own characteristics for two points raytracing is given. Considering that the two cross-holes do not often lie in the same plane in practical case, we eliminated this invalid effection to reconstruction picture by the corrected method derived, and the reconstruction precision was improved. The numerical and practical applica ion results show that the algorithm given by us is fast, stable, applicatable.