The invention relates to a borehole wall sloughing
analysis method which comprises the steps of parameter collection and input (1), initial stress
processing (2), first time of stress release (3), first step of second time of stress release (4A), second step of second time of stress release (4B), characteristic value evaluation (5), generalized force and generalized displacement (6), path curve balancing (7), and collapse pressure
processing (8). Evaluation is conducted according to a minimum obtained characteristic value (Mu1) m, and when the minimum obtained characteristic value (Mu1) m is more than 0, if m is less than M, m plus 1 arrows m, thus entering the second step of the second time of the stress release (4B); otherwise, a
total field is obtained; when the minimum characteristic value (Mu1) m is less than 0, a disturbance field is calculated according to an interpolation method; and the collapse pressure qcr and a plastic area distribution area corresponding to the qcr are calculated, so as to determine the density of collapse prevention
drilling fluid. The borehole wall sloughing
analysis method has the effect of being capable of analyzing the borehole wall stability of a
strain softening plastic stratum under the condition of non-uniform ground stress; and the density of the collapse prevention
drilling fluid is designed, thus playing the role of protecting a reservoir stratum during on-site drilling.