Overview

When drilling is stopped (or while drilling), the acoustic source, mounted on a drillstring, generates a pressure pulse. This excites both tube waves within the borehole and acoustic waves in surrounding formation. The resulting acoustic waves propagate through the formation, experiencing partial reflection on existing acoustic boundaries. Upon reaching borehole walls the reflected waves excite corresponding tube waves, which are being registered by receivers mounted on the drillstring. While incident and reflected waves propagate in formation, tube waves propagate within borehole reflecting from stabilizers and the bottom of the hole, disturbing reception of the informative signal as well as exciting additional waves in formation.