关键词: CO₂压裂, 对流换热, 数值模拟, 滤失效应

Abstract: To clarify the effects of key operational parameters on fracturing performance during convective heat transfer of CO₂ fracturing fluid in fractures(taking into account of filtration loss),numerical simulations were made on the heat and mass transfer of liquid CO₂ fracturing fluid in shale reservoir fractures.Focusing on fracture temperature,pressure and density fields,analysis centered on the influencing factors of CO₂ convection.The results show that after CO₂ injection,along the fracture length,the CO₂ fracturing fluid temperature gradually rose to a peak,then slightly decreased before stabilizing;the CO₂ pressure decreased gradually with a slow decline initially and a rapid decline later,eventually stabilizing; the CO₂ density decreased to a minimum then slightly rises before stabilizing.As the injection rate increases, the maximum temperature of the CO₂ fracturing fluid decreases and the total filtration loss increases.Raising the injection temperature increased CO₂ temperatures deeper in the fracture(farther from the inlet)and also raised total loss.Increasing the injection pressure raised the CO₂ temperature nearer the fracture inlet and reduced total loss.These findings can provide a theoretical reference for designing CO₂ fracturing operations in shale reservoirs.

Key words: CO₂ fracturing, convective heat transfer, numerical simulation, filtration effect