螺旋坐标下的因子分解合成炮叠前深度偏移

在合成炮叠前深度偏移的基础上，提出了一种高效的合成炮叠前深度偏移方法，即在螺旋坐标下用因子分解进行波场外推的混合法. 用因子分解进行波场外推分为因果过程和反因果过程两个显式求解过程. 这种螺旋坐标下的显式求解过程,提高了波场外推的效率. 根据相位编码原理,对多个射线参数的合成波场进行了编码叠加,基于射线参数实现了MPI并行计算,进一步提高了计算效率. 在推导了有关公式并进行定量分析之后,对Marmousi复杂模型进行了计算,并作了比较,结果表明本文方法具有精度高和速度快的特点,可用于实际资料的计算.

FACTORIZATION SYNTHESIZED-SHOT PRESTACK DEPTH MIGRATION IN THE HELICAL COORDINATE SYSTEM

Based on the synthesized-shot prestack depth migration,a new high efficient method for the synthesized-shot prestack depth migration is proposed.It is a hybrid technique which implements wavefield extrapolation with factorization in the helical coordinate system. The wavefield extrapolation is divided into two explicit solving processes. One is a causal process, and the other is an anticausal process. Such explicit solving processes in the helical coordinate system can improve the wavefield extrapolation efficiency. Moreover, based on the phase encoding principle, the synthesized-wavefield corresponding to multiple ray parameters is encoded and stacked. Then the calculations are implemented with MPI parallel algorithm based on the ray parameters. Thus the calculation efficiency is enhanced further. After deriving the relevant formulae and analyzing the computation cost quantitatively, numerical calculations for the Marmousi complex model are carried out and results comparisons are made. The imaging results show that the method presented in this paper has the advantages of high precision and good efficiency. So it can be applied to practical data processing.