Experimental deformation of shales at elevated temperature and pressure: Pore-crack system evolution and its effects on shale gas reservoirs

• DOI: 10.1016/j.petsci.2024.07.003
• Publication Date: 2024-07-02T16:56:58Z
• Authors: Yi-Wen Ju; Xin-Gao Hou; Kui Han; Yu Song; Lei Xiao; Cheng Huang; Hong-Jian Zhu; Li-Ru Tao
• Keywords: Brittleness; Cataclastic rock; Macropore

Although many studies based on naturally deformed samples have been carried out to investigate the pore-crack characteristics of shales, high temperature (T) and pressure (P) deformation experiments, which can exclude sample heterogeneity factors, simulate deep T-P conditions, generate a continuous sequence, are still rare. In this study, shales with different levels generated by triaxial compression methods including scanning electron microscopy, mercury injection, gas sorption utilized characterize their influence factors characteristics. Results indicate that T is primary factor influencing shale when P low, while dominant under conditions. At < 90 °C 60 MPa, undergo brittle macropores decrease due compaction pores, mesopores increase because interconnection micropores. 200 MPa< 110 experience brittle-ductile transitional deformation, macro- micropores extension open cracks plastic clay flakes respectively, dramatically. > subjected ductile micro- drop significantly intense in matrix continuously crack expansion. The permeability increases degree material contents predicted be key determining whether microcracks preserved after deformation. To account for these experimental results, an ideal model micro system evolution further proposed, provide guidance exploration resources or structurally complex zones.