This work constructed transparent fracture models to visually track swollen preformed-particle-gel (PPG) propagation through open fractures and water flow through PPG placed in the fractures. During injection, PPG propagated like a piston along a fracture and a gel pack was formed in the fracture. When water broke through the particle-gel pack after PPG placement, several channels were created that discharged water from the outlet while water was being injected. Investigation of factors that influence PPG injectivity and plugging efficiency revealed that PPG injectivity increases with fracture widths and flow rates but decreases with brine concentrations (on which the PPG swelling ratio depends). PPG can reduce the permeability for the fractures with different widths to the same level. Full-factorial experimental design analysis was performed to rank the influence of injection rate, fracture width, and PPG swelling ratio on pressure response, resistance factors, and injectivity.