Effective stress coefficient for P- and S-wave velocity and quality factor in sandstone, Example from Cooper Basin-Australia

Summary The velocities and quality factors of compressional and shear waves have been measured at ultrasonic frequencies in Cooper Basin sandstone under a rang of pore pressure and confining stress using a pulse-echo technique. The effective stress coefficient, n, is found to be less than 1 for both velocities and quality factors in the Cooper Basin sandstone. The pore pressure sensitivity of wave velocities decrease ( n approaches one) with the increase of differential pressure. In contrast, the effect of pore pressure on both P- and S-wave quality factors increase ( n decreases) with increasing differential pressure. The strong influence of pore pressure on Q p and Qs is attributed to behavior of pore filling and grain coating clay minerals.

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