LAUSR

Abstract Lost circulation is one of the most common and costly problems in drilling. The stability of the plugging zone is a key factor determining the lost circulation control. In this paper, an analytical model is derived based on the catastrophic theory, which considers key parameters affecting the stability of the plugging zone, such as formation parameters, contact parameters and plugging zone parameters. The maximum plugging pressure (MPP) can be calculated by this model to quantitatively evaluate the stability of the plugging zone. The validation case shows that the calculation result is in good agreement with the experimental measurement. In addition, the sensitivity analysis is performed and shows that the length of the plugging zone, the sliding friction coefficient of the fracture surface and the Young's modulus of plugging zone are positively correlated with MPP, but the shear height of plugging zone, sliding friction coefficient of lost circulation materials (LCMs) and Poisson's ratio of the plugging zone are negatively correlated with MPP. The model can be used to predict the MPP in lost circulation control and considered as a reference for the optimization of the LCMs and plugging program.