Physical modeling of seismic illumination and SWD
Joe Wong, Hongliang Zhang, Nasser Kazemi, Kevin L. Bertram, Kristopher A. H. Innanen, Roman Shor
Surface land and marine seismic data contain reflected waveforms from the subsurface that can be back-propagated through a background medium for imaging purposes. In complex structures, it is possible that wave energy penetrate only weakly into some areas, or not at all causing seismic shadows (i.e., the illumination problem). Deficiencies in seismic illumination can be mitigated if deep subsurface sources are used in acquisition.
Drill-bits generate significant elastic wave at locations deep below the surface. Moreover, since drilling anyway is necessary, using the drill-bit-rock interaction as a seismic source comes with no extra cost or interruption in the drilling process. The possibility exists that the drill-bit is a viable subsurface seismic source and that seismic-while-drilling (SWD) is a practical method for improving seismic illumination.
The CREWES seismic physical modeling group, in collaboration with the University of Calgary Department of Chemical and Petroleum Engineering, has undertaken a physical-modeling project to investigate SWD (seismic-while-drilling). This article reports on the results in regards to both the illumination problem and the recording of complex seismic waveforms.