Application study of 3-C offset VSP data in coalbed gas exploration

Using 3 C offset VSP data,many results can be achieved by using following techniques.The techniques include 3 C rotation,wave field separation with domain transform,interval velocity inversion with picked first break,VSP wave depth imaging with ray tracing algorithm,which is based on Fermat's principle and absorption coefficient estimated with combination of seismological kinematic and dynamic properties.The techniques have been successfully applied to offset VSP data from an area in Shanxi and good processing results have been obtained.These results show that it is helpful to make full use of the data extracted from VSP wave field for detailed reservoir study and interpretation.