Experimental study on permeability evolution in propped shale fracture

In the process of shale gas fracturing exploitation, the permeability of propped shale fracture is one of the key factors that affect the fracture conductivity. This work focuses on the effects of swelling and embedment on permeability in propped shale using experimental method. The Pulse test method was used to measure the permeability of adsorbed gas and non-adsorbed gas. The permeability of He, which is a non-adsorbing gas, in both granite and shale was measured for references. The reduction of permeability in shale is caused by the existence of proppant embedment. The “U shape” feature is observed in CO₂ permeability curve, which indicates that the swelling also has a significant effect on the permeability in shale. Compared with the permeability curve of He, the CO₂ permeability is even lower and achieves the minimum value at the pressure condition around the Langmuir pressure.