三维VSP数据的波动方程偏移成像

常规的三维VSP地震数据偏移成像大都使用基于射线理论的Kirchhoff积分方法在共炮点道集中进行，因此对地下速度横向变化大的复杂构造区适应性差、效率很低。基于三维VSP地面激发井中接收观测系统的特殊性，利用地震波场的互易性原理，提出了一种在共接收点道集中进行三维VSP地震数据波动方程偏移成像的方法，不仅极大地提高了三维VSP偏移成像的计算效率，而且还适用于速度横向变化大的复杂构造区。为了利用时间域偏移成像方法对速度模型的相对不敏感特性，在三维VSP偏移成像中，借助于波动方程叠前深度偏移成像算法的概念，还提出了一种可以满足时间域速度模型横向变化要求的波动方程叠前时间偏移成像方法，拓展了波动方程叠前时间偏移成像的应用范围。

Wave Equation Migration for 3-D VSP Data

The conventional migration for 3 D VSP seismic data resorts to the use of Kirchhoff integral, which is based on the ray theory, to be implemented in common shot point gather. So it has poor adaptability and low efficiency in complex structure area with large lateral subsurface velocity variation. Based on the particularity of receiving and observing system in 3 D VSP surface shot hole and by use of reciprocity theorem of seismic wave field, a method of carrying out wave equation migration is proposed for 3D VSP seismic data in common receiver gather. The method can not only strongly improve the calculating efficiency of 3D VSP migration, but also be applied in complex structure area with large lateral subsurface velocity variation. In 3D VSP migration, in order to use the relative insensitivity of time domain migration to velocity model, through using the concept of wave equation pre stack depth migration, the paper put forward a wave equation pre stack time migration method, which can meet the lateral variation requirements of velocity model in time domain and extends the application range of wave equation pre stack time migration.