Abstract: Multi stage limited-entry fracturing is one of the most effective methods to improve the production capacity of low-permeability reservoirs in the Bozhong 25-1 Oilfield. However, when reservoir characteristics and flow limiting fracturing process parameters jointly affect each other, the mechanism of multi cluster fracture propagation is still unclear. Based on a large-scale true triaxial fracturing simulation experimental platform, we conduct experimental research on the multi cluster fracture propagation law of artificial rocks with similar physical properties in the target layer. The influence of factors such as perforation cluster spacing, cluster number, and horizontal stress difference on the multi cluster fracture propagation state is analyzed. The results indicate that increasing the spacing between clusters has little effect on the initiation pressure of rocks, but it weakens the interference between cracks and promotes the uniform expansion of multiple clusters of cracks; the increase in the number of perforation clusters will weaken the resistance of rock plastic deformation to crack propagation and increase the scale of crack propagation; when the horizontal stress difference is less than 6 MPa, multiple clusters of cracks exhibit a staggered expansion of transverse and longitudinal cracks; the increase in fracturing fluid displacement and viscosity can increase the net pressure inside the fracture, and the morphology of multiple clusters of fractures becomes more complex. This study provides a reference for optimizing the parameters of flow limiting fracturing technology in low-permeability.

Key words: limited-entry fracturing, true triaxial simulation, multi-cluster fractures, low-permeability reservoirs, offshore oilfield