Drillbit Seismic Interferometry with and without Pilot Signals

We process for interferometry purposes the seismic signals generated by a drillbit source in a first well and recorded by seismic receivers located in a second borehole, and at the surface near the well. We compare the standard interferometry results, obtained by using the raw drillbit data without pilot signal, with new interferometry results obtained by using the drillbit seismograms correlated with a reference pilot signal. The analysis of the stationary phase shows that the coherent noise affects the final results, which have different S/N levels. The interferometry methods are compared by using different deconvolution approaches. The analysis shows that the results agree with the conventional drill-bit seismograms, and that using the reference pilot signal improves the quality of the drillbit wavefields redatumed by the interferometry method.