Drill-bit seismic and pilot seismograms contain drillstring periodicities from signal and environmental noise sources. These coherent components are similar in seismic-while-drilling correlations, and their joint contribution may cause distortions in signal processing. Numeric modeling of the drillstring transmission line is used to correctly interpret the axial and torsional events with similar propagating modes of signal and noise. The reflection coefficients are computed for drillstrings of arbitrary materials, and their average mechanical features are related to the axial and torsional group velocities obtained by the dispersion equations. Fitting of the periodical components in the real seismograms is used to automatically correct the drill-bit pilot delays and to estimate the surface and downhole boundary conditions.
No takes yet. Share an insight, caveat, or question.
Poletto et al. (2001) studied this question.
Synapse has enriched 4 closely related papers on similar clinical questions. Consider them for comparative context: