Directive Geophone

There may be good reason to consider planting geophones at an angle to enhance energy arriving at high incidence angles. This paper will examine two issues: the fidelity of geophones planted with a tilt, and the potential benefit of data collected with tilted geophones. It has been found, via lab measurements, that if a conventional geophone is tilted at 40° from vertical, then this will cause 70% losses of its maximum response (Bertram et al, 1999). The author has measured geophone properties in the field under static (passive source) and dynamic (active source) modes. In static mode, conventional geophones were observed operating normally up to 30º of tilt. In dynamic mode, a tilt of 60º was observed to cause about 90-95% losses of the maximum while no losses were observed at tilt angles ranging from 15-45º. The fact that geophones can maintain response integrity at tilted angles can be used to create directionally tuned arrays to enhance energy arriving at higher incidence angles. Directive or "Steering and Fixed Angle Geophone" (patent pending), presented here, is an attempt to improve the recovery of energy from longer offsets at acquisition stage.