A systematic experimental and modeling study of water adsorption/ desorption behavior in organic-rich shale with different particle sizes

Understanding the behavior of water-shale adsorption/desorption is of fundamental importance in evaluating in situ shale oil/gas reserves, improving shale oil/gas production and reducing the environmental impact of fracturing fluids. The isotherms and kinetics of water adsorption and desorption in organic-rich shale with three particle sizes (20-40 mesh, 40-60 mesh and 60-80 mesh) were measured at temperatures of 293 K, 303 K and 313 K, and the unclosed hysteresis behavior in water-shale adsorption/desorption isotherms was studied. Then, six thermodynamic models (including the DS1, DS2, DW, BET, GAB and Dent models) and four kinetic models (including the PFO, PSO, DE and Unipore models) were used to interpret the isotherms and kinetics, respectively. Furthermore, thermodynamic parameters, including Ali, AS and AG, and kinetic parameters, including the rate constants and activation energy, were extracted. Finally, these results are discussed in relation to the pore structure, surface functional groups, temperature, relative pressure and particle size. This work provides a systematic understanding of the isotherms, hysteresis, thermodynamics and kinetics of water adsorption/desorption in organic-rich shale.