Zero-offset reverse time migration for prediction ahead of tunnel face
反射地震零偏移距逆时偏移方法用于隧道超前预报

To implement fast and effective acquisition and real-time prediction ahead of tunnel face,this paper presents a reverse time migration approach to looking ahead of tunnel face based on the wave equations.A reflected acquisition scheme PMZO(Plus Minus Zero Offset)applied to a limited space in tunnel was also proposed for obtaining the seismic data that is applicable to the approach presented in the paper.We analyze the relation of reflected time-offset curves and characteristics of reflected amplitudes by using synthetic zero offset data in tunnel acquisition and discuss the interpretation for tunnel seismic data.In a model with a few faults in front of tunnel face,the numerical examples show that accurate images have been obtained ahead of the tunnel face by implementing the PMZO acquisition and the reverse time migration.