Abstract: Pressure-bearing plugging is an important method to solve the problem of lost circulation in fractured formation. Accurate prediction of pressure-bearing capacity of leakage formation is the core basis of scientific application of pressure-bearing plugging technology. For this purpose, on the basis of analyzing the variation of fracture width under non-uniform in-situ stress, the crack tip stress intensity factor when considering in-fracture plugging is derived based on superposition principle, and an analytical model for predicting the pressure-bearing capacity of plugged fractured formation is established. Compared with the traditional model, the prediction results of this model have higher accuracy and reliability. Finally, the influence of different engineering and geological parameters on the pressure-bearing capacity of plugged fracture is analyzed. The results show that increasing the fracture tip length and reducing the fluid pressure at the fracture tip during plugging treatment are beneficial to improving pressure-bearing capacity of fractured formation. When a low-permeable plugging zone is formed in the vicinity of borehole wall, it is necessary to optimize the length of the plugging zone to maximize the pressure-bearing capacity of plugged fracture. When the formation permeability is determined, pressure-bearing capacity of plugged fracture decreases with the increase of the ratio of in-situ stresses, and increases with the increase of elastic modulus, Poisson's ratio and fracture toughness.

Key words: fractured formation, lost circulation, fracture width prediction, pressure-bearing plugging, parametric analysis