Abstract：In recent years，extensive attention is poured into the waterfrac treatment for its simple application and low fracturing costs，and it has already made an obvious effect to increase the yield for the fracturing in some low permeability reservoirs. It is well known that the effect on waterfrac treatment mainly comes from the roughness and relative shear moving in the crack surfaces，but the theoretical researches are not so many on the crack closing shape of waterfrac treatment，and there are not some effective theories to guide the construction in oil field. Based on the full inspection of the relevant literature at home and abroad，the fracture characteristic is analyzed for the waterface treatment and the crack closing shape is analyzed with the mechanical methods. The shear strength models are established for waterfrac treatment under the partial crack opening and shear moving of the crack surface. It reveals the mechanism and the reasons for increasing well production from waterfrac treatment and it will also provide a theoretical basis for the future constructional design in waterface treatment.
