Abstract: Pre-existing microscale fractures, cracks and pores in geological layer, which makes the rock or/and stratum heterogeneity, response the difference of rupture characteristics under artificial injection. The exploitation and development of unconventional oil and gas reservoirs represented by tight oil and gas accounts for an increasing proportion of China’s oil and gas production capacity, and artificial fractures are often produced by hydraulic fracturing to enhance oil and gas flow and achieve the scale of economic production, they also are the important target for CO2 injection and geological storage. Based on the true triaxial hydraulic fracturing experiment and the microseismic data in geological setting, this paper studies multiscale rupture process in sandstone through the temporal and spatial characteristics of acoustic event and the microseismic event. The results show that the pre-existing fractures in rock dominate the rupture pattern under the stable triaxial hydraulic fracturing stress and geological settings.

Key words: acoustic emission, crack, CO₂ geological storage, hydraulic fracturing, anisotropy