“…The main damage caused by hydration is the result of clay mineral swelling, dissolution, and the shedding of clastic particles. − Variations in the pore structure resulting from hydration mainly result from the dissolution of minerals and result in the dislodging of mineral particles and the concomitant enlargement of pores. , However, higher clay mineral contents may lead to pore blockage due to clast swelling and the concomitant pore shrinkage. , In addition, hydration reduces the strength of shale, which may exacerbate wellbore collapse or aid hydraulic fracturing. − Hydration may even generate micro-fractures and form complex fracture networks connecting micro- or nano-pores. − With the progress of hydration, micro-fractures will extend and connect, ultimately developing transmissive fracture systems. , Thus, hydration promotes changes in the pore structure and the physical characteristics of shales, manifest as changes in the porosity and permeability, with clay mineral type, hydration time, pH, and ionic composition of the water (i.e., different fracturing fluids) all impacting the response. − However, the detailed imbibition process and hydration damage on transitional shale has not been fully revealed.…”