Seismic-while-drilling drill-bit source by ground force: Concept and application

For four decades, the use of the drill-bit seismic source has been evaluated extensively and investigated for seismic-while-drilling (SWD) purposes. After an initial diffusion phase, however, the routine application on drill-bit reverse vertical seismic profiling (RVSP) has declined because of issues related to variability in the signal-to-noise ratio of drill-bit signals obtained with different drilling conditions. Consequently, additional efforts have been dedicated to improving the recording of reference signals. Recent technology developments enable direct ground-force pilot measurements at downhole positions close to the bit, which enable reliable estimations of the far-field drill-bit-radiated signature. The knowledge of the ground force below the source in the near-field is a key aspect not only for the exploitation of the drill-bit source but also for conventional seismic vibrator sources. The SWD deconvolved results obtained …