Osmotic effects on the microstructure of Ashfield shale

抄録

Preliminary results of a comprehensive microstructural investigation aimed at studying the influence of osmotic effects in Ashfield shale, a low permeability sedimentary rock from the Sydney Basin (Australia), are presented in the paper. Natural rock specimens were exposed to different brine solutions to assess their influence on rock microstructure. Qualitative as well as quantitative experimental techniques were used to evaluate changes in mineralogical composition (XRD analysis), Cation Exchange Capacity (CEC), cation/ion concentration (chromatographic analysis), specific surface, structural arrangement (Scanning Electron Microscopy) as well as pore size distribution (Mercury Intrusion Porosimetry). Test results show an important influence of the applied osmotic potential on specific surface, CEC and pore size distribution and to a lesser extend the structural arrangement assessed via SEM. These changes occur without important variations in the mineralogical composition of the rock.