Kris Innanen

Research Note: Experimental measurements of Q-contrast reflections

While seismic reflection amplitudes are generally determined by real acoustical impedance contrasts, there has been recent interest in reflections due to contrasts in seismic-Q. Herein we compare theoretical and modelled seismic reflection amplitudes for two different cases of material contrasts. In case A, we examine reflections from material interfaces that have a large contrast in real-valued impedance (ρv) with virtually no contrast in seismic-Q. In case B, we examine reflections from material interfaces that have virtually no contrast in ρv but that have very large seismic-Q contrasts. The complex-valued reflection coefficient formula predicts non-zero seismic reflection amplitudes for both cases.We choose physical materials that typify the physics of both case A and case B. Physical modelling experiments show significantly large reflections for both cases – with the reflections in the two cases being phase shifted with respect to each other, as predicted theoretically. While these modelling experiments show the existence of reflections that are predicted by theory, there are still intriguing questions regarding the size of the Q-contrast reflections, the existence of large Q-contrast reflections in reservoir rocks and the possible application of Q-reflection analysis to viscosity estimation in heavy oilfields.