An experimental and numerical investigation on mechanical behavior of sandstone specimens saturated in brine

Abstract

The mechanical behavior of reservoir rock saturated in brine is of great interest to scientists and engineers for geological CO2 sequestration in deep saline aquifers. However, the mechanical behavior of brine-saturated sandstone under triaxial compression has not been fully investigated, particularly with numerical simulations. In this study, an experimental study and numerical simulation were carried out on brine-saturated sandstone specimens to explore the mechanical properties in sandstones subjected to various brine salinities. Laboratory uniaxial compression tests were conducted on the brine-saturated sandstone specimens, and enhancements in strength and elastic modulus were observed with increasing brine salinity. Scanning electron microscopy results showed NaCl crystals deposited in the pore spaces, which provides evidence of strength and modulus variation in sandstone after brine saturation. Microparameters in a PFC3D numerical model were calibrated for each brine salinity condition, and the numerically simulated results were compared with the experimental results. The numerical results agreed well with the triaxial compression test results, indicating the appropriateness and reasonability of the calibrated models.