SEGJ Technical Conference

Effect of confining pressure on P-wave velocity in imperfectly saturated sands - Computed P-wave velocities in sands by the use of heterogeneous saturation model-

Abstract A series of P-wave propagation tests were conducted for saturated, imperfectly saturated and air-dried sand specimens. Measurements were conducted in a chamber under confining pressures ranging between 0 and 10 a.t.m. Under an imperfectly saturation condition, P-wave velocity in sand gradually increases with confining pressure because air bubbles are compressed or dissolved in water under the effect of pressure. The confining pressure-velocity curves of imperfectly saturated sand cannot be estimated by Gassmann-Domenico substitution equation assuming uniform saturation. The velocities depend not only on the degree of saturation but also on the types of saturation. We proposed a non-uniform saturation model based on the Hill average. We can explain the experimental results for imperfectly saturated sand with this model.