Hydraulic Fracturing Test and Its Effect Evaluation of a Difficult-to-Collapse Ore Body in a Copper Mine
A rock fracturing material model test was conducted to investigate the feasibility of hydraulic fracturing for a difficult-to-collapse ore body in a copper mine.Numerical simulations were applied to investigate fracturing crack propagation under various cluster spacing,construction displacements,as well as construction scales and working conditions.Industrial hydraulic fracturing tests and monitoring were conducted for two types of fracturing processes,including surface open-hole and perforation.The results indicate that the ore body has a favorable fracturability,possessing the potential to form multiple complex fractures.The numerical simulations show that a hydraulic fracturing construction displacement is within the range of 4-5 m3/min and a single-stage fluid volume of 200-450 m3 can meet the demands of fracture half-lengths of 40-70 m,resulting in complex fracture networks.The hydraulic fractures of two wells in the industrial test extend relatively short in the short axis direction of the ore body,which overall conforms to the extension law and basically meets the design requirements.Compared to open-hole fracturing,perforation fracturing uses multiple clusters of perforation and temporary plugging turning(perforation+internal fracture),resulting in denser hydraulic fractures,and the monitored fracture length is significantly shorter than the designed fracture length.The research results can provide a basis for the fracturing induction of natural caving mining method in this mine.