摘要 从波动方程出发，利用有限差分法导出波场外推公式，由此可以进行波场正演计算和偏移。用 P 波方程编制的偏移程序 VSP MIG 既可用于地面资料的偏移，也可用于井中资料的偏移;既可用于 P 波偏移，也可用于 P-SV 波偏移，但需相应的变化速度模型。对于 P 波和 P-SV 波，偏移的成像时间也是完全一样的。分别偏移分离后的上行 P 波和上行 P-SV 波，可以得到纵波和横波两张偏移剖面，这样比纵、横波资料的联合一次偏移可以得到更多的信息。
Abstract：Based on wave equation theory, we can use finite difference method to derive wave-field extrapolation formula, by which both wave-field modeling and migration can be made.The migration program VSP MIG that was developed using P-wave equation may be used to migrate both surface seismic data and VSP data,Besides, it may be applied to the migrations of. P-wave data and P-SV wave data, in which case the original velocity model should be modified properly, The migrated image times for P-wave and P-SV wave respectively are absolutely equal.The migrations of upgoing P-wave and upgoing P-SV wave which have been separated can offer migrated P-wave section and migrated S-wave section, Thus, we can get more informations than from simultaneous migration of P-wave and S-wave data.
