叠前时间偏移成像技术及其应用

零炮检距剖面是地震反射成像过程中的重要成果。通过弯曲反射界面模型,分析了共中心点(CMP)道集与共反射点(CRP)道集的差别,认为当反射界面倾斜时,常规处理中的CMP叠加不能得到准确的零偏移距剖面,而沿CRP道集叠加的叠前时间偏移能得到准确的零偏移距剖面,另外,还介绍了叠前时间偏移的实现方法和步骤,包括预处理、偏移速度场的建立和偏移后CRP道集的处理等,并结合实际资料进行了效果分析。

THE PRESTACK TIME MIGRATION TECHNOLOGY AND ITS APPLICATION

The zero-offset(z_0) section is an important achievement in seismic reflection imaging.The differences between the common midpoint(CMP) and the common reflection point(CRP) are discussed on the basis of the dome-like reflector model.In usual seismic data processing,we cannot get the correct z_0 sections if oblique layers are imaged.However,the prestack time migration technique using CRP stacking can help us to obtain the correct z_0 sections.This paper discusses the key steps in the application of such prestack time migration techniques as seismic data preprocessing,construction of migration-velocity field and CRP gather processing after migration.The processing effects are demonstrated with real data.