Evaluation of the mechanical behaviour of brine+CO2 saturated brown coal under mono-cyclic uni-axial compression

摘要: Abstract CO2-sequestration and ECBM techniques necessitate injection of CO2 into coal reservoirs that are saturated under various pore fluid conditions, resulting in alterations mechanical properties. In this study, we evaluate the effect chemistry interaction time on degradation. Uni-axial compressive strength (UCS) tests, ARAMIS photogrammetric analysis, micro-CT imaging, Fourier transform infrared spectroscopy (FT-IR) combinedly used to such interpret causative factors water, water + CO2, 10% brine + CO2 20% coal. The results indicate irrespective chemistry, parameters including UCS, Young’s modulus brittleness index reduce significantly coal, due moisture adsorption-induced softening effect. presence fluids causes additional each property, corrosive chemical interactions occur acidic environments, energy reduction plasticization-induced macromolecular structure. direct comparison FT-IR spectrums natural CO2-interacted concludes structure possibly causing degradation mass plasticization extraction pore-constricting hydrocarbons. volumetric strain analysis image-based 3D-reconstruction infer water + CO2 saturation increase ductile properties a dilatancy deformation extensive fracturing, upon loading. contrast, higher order NaCl concentrations (i.e. brine) crystallization an elevated consequently altering sample deformation, failure pattern fracturing mechanism. Although, cause continues with increasing all significant occurs at short-term period latter longer saturations have caused only gradual reductions, probably rapid adsorption process matrix.