Hysteresis analysis on petrophysical and mechanical properties of carbonate rocks

Hydrostatic compression tests on rocks, if conducted at stresses below failure, typically exhibit both non-linearity and hysteresis in the stress–strain curve. This behavior can be associated with the presence of cracks and pores. In this work, porosity and bulk volume deformation were analyzed and the different behavior under loading/ unloading conditions reveals the grain/pore interaction influence on these properties. Experiments were conducted increasing hydrostatic pressure from 400 psi to 1000 psi, registering loading and unloading data, on carbonate samples of American outcrops. The dissipated energy related to frictional sliding and adhesion effect, during confinement cycle, was estimated by the area of hysteresis loop in the effective pressure versus bulk volume graph.