NUMERICAL AND ULTRASONIC EXPERIMENTAL SIMULATIONS OF ELASTIC WAVE PROPAGATION AROUND HOLLOW CYLINDER

A laser-ultrasonic experimental setup was used to study, at a reduced scale, the wave propagation inside and around fluid-filled wells. Simulations tools were also developed and calibrated from comparisons with experimental signals. These tools serve as a connection to realistic scale. A semi-analytical approach, the discrete wave number method was first used to compute signals in a simplified geometrical configuration. This method is fast enough to be used in the identification of the main parameters that describe at best the experimental signals. Then a finite difference scheme was implemented in order to describe accurately the actual well. The two methods describe the attenuation mechanisms by using the Kelvin-Voigt model for the solid and the Maxwell model for the fluid. Comparisons between numerical and experimental waveforms, obtained in the two fundamental elastic configurations: the fast and the slow formations, show very good agreement in arrival times, waveforms and relative amplitudes. This satisfactory result provides insights useful for the recognition and interpretation of wave propagation in complex media. Such is the case of modern sonic-logging technology.