Seismic While Drilling: Basic Experiments Using a Percussion Drill as an Energy Source

We discuss the feasibility of performing SWD (Seismic While Drilling) surveys utilizing a percussion drill as an energy source. This drilling technology is widely used in the drilling industry because it enables safe, economical, and rapid drilling. For SWD surveys, a broad source frequency spectrum is essential; however, the frequency content of seismic signals normally generated by percussion drilling is severely band limited because it is primarily controlled by the impact rate of the drill. In this paper, we report attempts at broadening the spectral energy output of a percussion drill. The frequency content of percussion drill signals can be controlled by manual variation of the hydraulic pressure input during drilling. Because hydraulic pressure change affects both the impact power and the rate of drilling, this results in a change in the frequency of drilling vibrations. We show that the response after processing is comparable with a conventional shot-record, but the percussion drill and cross-correlation method still requires improvements before it can be considered equal to conventional data.