摘要 本文讨论了 Born 近似与 Rytov 近似的相互关系,并对地面反射、VSP、井间和四周观测系统在异常体速度与背景速度相差5%、10%以及15%的条件下,用这两种近似方法作了重建图像的实验。其结果表明,速度差低于10%时,无论 Born 近似或 Rytov 近似,更射层析均优于透射层析。此时,Rytov 近似的透射层析优势消失,这一结论与传统观点相悖。当速度差大于10%时,Rytov 近似透射层析优于 Born 近似。实验结果还说明,在地面激发、四周观测时,波动理论层析效果最佳,此点与射线理论是一致的。
Abstract：The relationship between Born's approximation and Rytov's approximation is discussed here. The two approximations are respectively used to make image reconstruction of the seismic data of surface reflection，VSP，interborehole and four side observation when the velocity contrast between abnormal area and background are 5%，1000 and I5%respectively. Consequently，when the velocity contrast is low than 1000，both Born's approximation and Rytov's approximation show that reflection tomography is better than transmission tomography. In other words，in this case，Rytov's approximation loses its advantage on transmission tomography,which is contrary to traditional conclusion. when velocity contrast is higher than 1000, Rytov's approximate transmission tomography is superior to Born's approximation.It is also shown that when receivers are on four sides of a surficial source，wave theory tomography is the optimum，which is consistent with ray theory tomography.
