Filtering harmonic noise encountered in reverse VSP

Surface seismic noise is often be the dominant component recorded during reverse vertical seismic profiling (RVSP). In the RVSP technique the seismic source is lowered into the wellbore while receivers are deployed on the surface. It is not uncommon that the desired direct and reflected seismic signals are several times below the background noise level. An adaptive noise filter is presented and applied to both synthetic and to real data. The filter is designed to suppress stationary harmonic noise as might be generated by reciprocating engines at a drill rig site. A finite difference algorithms is used to model both the seismic signals and the noise encountered in an RVSP environment. Real RVSP data are shown to demonstrate the effectiveness of the filter in removing harmonic background noise.