Numerical simulation of triaxial experimental results on Sandstone using critical state mechanics

Abstract

In carbon capture and storage schemes, the carbon dioxide (CO2) can be injected at high pressures and low temperatures for permanent storage in deep reservoirs. In the North Sea, the storage sites will be predominantly sandstone. To study the effects of these conditions on the rock surrounding the injection site, triaxial tests on sandstone were conducted until failure using representative in-situ stresses to estimate the mechanical properties of the rock. A theoretical constitutive model, using Finite Element Modelling (FEM), describing the stress-strain behaviour and damage evolution of rock during triaxial testing is presented alongside the results of the tests. The model reproduced the experimental outcomes well and it was used for the estimation of the critical state mechanic parameters. Lower temperature indicated higher strength of sandstone, a decrease in the Poisson’s ratio and consequently an increase in damage.