VSP逆时偏移处理

VSP逆时偏移处理是一种适用性很强的波动方程偏移方法。其控制方程既能描述波的全方向传播，又能消除层间多次反射波。本文通过推广Claerbout成像原理确定出成像条件，以实际VSP数据求出边界条件，按时间逆的次序求解双程无反射波动方程。在每一步外推中，利用成像条件求得相应成像点的偏移值。当逆时外推至最小成像时间时，就能得到整个剖面的偏移结果。理论与实际资料处理表明，该方法能适应各种速度的变化，使偏移后的剖面具有较高的分辨率和信噪比，而且处理效率极高。

VSP reverse-time migration

VSP reverse-time migration is a well adaptable wave equation migration method. Its control equation not only describes all-direction propagation of seismic wave but also removes interbed multiples. Clearbout's image principle is generalized to determine image condition, real VSP data are used to determine boundary condition, and two way reflection-free wave equation is solved by making reverse-time extrapolation. In each step of extrapolation, the migration value at relevant image point is obtained by using the image condition. The complete migration of a seismic section is achieved when reverse-time extrapolation reaches the minimum image time. It is proved theore-tieally and practically that this method is applicable to any velocity variation and makes the migrated section have both good resolution and high S/N ratio. Besides, this method results in high processing efficiency.