Abstract This study proposes methane in-situ explosive fracturing (MIEF) for reactivating closed fractures in aging shale gas reservoirs. Employing a split Hopkinson pressure bar (SHPB) system, this study investigates the impact-shearing damage characteristics of the split-re-closed shales. Changes in fracture surface roughness are analyzed via 3D laser scanning, and fracture spaces are reconstructed and quantified using X-ray tomography. Based on numerical simulation methods, the impact-shearing damage process of reclosed fractures is discussed. Results show that rock debris exfoliation during impact shearing reduces fracture surface roughness, with roughness parameters Z 2s and θ max /(C + 1) exhibiting a linear positive correlation. The 3D box dimension of fracture surfaces decreases after impact shearing and shows an exponential correlation with parameter Z 2s . The 2D box dimension of the damaged areas of the fracture surface displays fractal characteristics and exponential positive correlations with both Z 2s and θ max /(C + 1). Fracture apertures in split-re-closed shale samples increase by 5–19 times after impact shearing, with the increment positively correlating with roughness parameter Z 2s . Areas with high roughness initiate damage earliest during impact shearing, and periodic “shear dilation – fracture damage” cycles between the upper and lower fracture surfaces lead to (1) non-uniform damage distribution, (2) rock debris exfoliation, and (3) shear misalignment. These effects collectively prevent complete fracture closure, thereby generating self-propping behavior in impact-sheared fractures.
Tang et al. (Wed,) studied this question.