  Predictive modeling of CO2 storage sites requires a detailed understanding of
physico-chemical processes and potential challenges for scale-up. Dramatic
injectivity decline may occur due to salt precipitation pore clogging in
high-salinity reservoirs, even over a short time frame. This study aims to
elucidate the adverse impact of CO2-induced salt crystallization in porous
media on the geomechanical properties of near-wellbore reservoir sandstones. As
the impact of salt precipitation cannot be isolated from the precursor effects
of interaction with CO2 and carbonic acid, we initiated our study by a
comprehensive review of CO2 chemo-mechanical interactions with sandstones. We
conducted laboratory geochemical CO2-brine-rock interactions at elevated
pressures and temperatures on two sets of porous sandstone with contrasting
petrophysical qualities. Two paths were followed: treatment with (a)
CO2-acidified brine at 10 MPa fluid pressure and 60C for 7 days, and a second
subset continuation with (b) supercritical injection until complete dry-out and
salt precipitation. Afterward, the core samples were tested in a triaxial
apparatus at varying stresses and temperatures. The elastic moduli of intact,
CO2-reacted, and salt-damaged sandstones were juxtaposed to elucidate the
extent of crystallization damages. The salt-affected specimens showed a maximum
of 50 percent reduction in Young's and shear moduli and twice an increase in
Poisson's ratio compared to intact condition. The deterioration was notably
higher for the tighter rocks with higher initial stiffness.
