Response of a large, low-porosity rock sample to hydromechanical loading

Abstract

A laboratory framework is developed for tracking infiltration and measuring hydromechanical parameters of a 150 × 150 × 250 mm³ confined specimen of Westerly granite. Many hydrogeological processes are initiated by fluid infiltration into dry rock, yet assessment of this phenomenon is rare because of the minuscule pore volume V_p (of order 0.1 mL) associated with typical laboratory-sized samples of low-porosity rock. We demonstrate that a single experimental design for measuring infiltration and saturation of a large (V_p of order 50 mL) specimen provides an array of reliable parameters for modeling critical hydrogeological processes and geophysical phenomena. Observing the sample fluid uptake indicates infiltration is modeled effectively by a sharp front separating fluid-infiltrated and dry regions. Additionally, by monitoring the fluid exchange during unjacketed loading, accurate values of the unjacketed pore $K_s\text{'}\text{'}$ and bulk K_s′ moduli are obtained, and by using isotropic poroelasticity, the measured and predicted values of Skempton coefficients B are shown to be in good agreement.