Abstract: The 3D multi-horizontal wells hydraulic fracturing technology is the core technology to improve the production and recovery of unconventional oil and gas reservoirs. There is more complex interaction between adjacent fractures and adjacent horizontal wells, and the hydraulic fractures show complex morphology in the 3D space. This study conducted a 3D multi-well fracturing experiment. Using typical cases, the spatial distribution of the 3D fracturing network was investigated considering the interaction between fractures and wells. Under true triaxial conditions, multi-wellbore alternating, zipper fracturing was carried out, and the changes of pump injection pressure and pressure in the fracture were monitored. Through 3D reconstruction of the spatial morphology of 12 main fractures of three wells, it is found that the pre-fractured wells have an attractive effect on the hydraulic fractures of the subsequent fractured wells, and the fractures of the subsequent fractured wells show asymmetric expansion. The formation of branching fractures is related to the local stress field inversion induced by the main fractures, and the connectivity with the main fractures is good. Both of them are important components of the 3D fracture network. The statistical results of fracture density show that there is periodicity in the distribution of the interaction zone between main fractures, and the periodicity of the local fracture density, fracture geometry and corresponding breakdown pressure are formed. The above experimental results can provide a reference for the optimization of fracturing schemes.

Key words: 3D multi-horizontal well hydraulic fracturing, fracture network, stress shadow, breakdown pressure