Study on the Law of Multi‐Fracture Propagation in Different Fracturing Fluid Viscosity

ABSTRACT Using the TCHFSM‐I large‐scale accurate triaxial fracturing seepage simulation device independently developed, acoustic emission monitoring system and high‐temperature–high‐pressure dynamic flowmeter, the fracturing multi‐fracture synchronous propagation law of different viscosity fracturing fluids was studied with homogeneous cement mortar specimens as the object. The results show that (1) fracturing fluid's viscosity significantly affects the synchronous propagation of multiple fractures, especially when the perforation distance is small. Decreasing the viscosity of the fracturing fluid can reduce the effect of stress shadow and make the multi‐fracture propagation more balanced. (2) Under different fracturing fluid viscosity conditions, the evolution characteristics of injection pressure are significantly different. Reducing the viscosity of the fracturing fluid can reduce the initiation pressure, but the initiation time becomes longer to a certain extent. (3) The fracturing process can be divided into three stages: supplementary filtration, energy accumulation‐failure, and energy remnant. Each stage's acoustic emission event location map can well reflect the fracture propagation law. In the fracturing operation, the viscosity of the fracturing fluid can be reduced appropriately, and the fracturing effect can be improved.