Uncertainty analysis method for external collapse loads of extra-deep well casings

The invention discloses an uncertainty analysis method for external collapse loads of extra-deep well casings. The method comprises the following steps of: S1, establishing an external collapse load model of an extra-deep well casing according to an extra-deep well geological condition; S2, obtaining a probability density function and a cumulative probability function of an external collapse loadof the extra-deep well casing through a probability statistical method according to the external collapse model; S3, obtaining cumulative probability distribution functions of casing external collapseloads at different well depths according to the cumulative probability function of the external collapse load of the extra-deep well casing; and S4, selecting a corresponding casing anti-collapse safety coefficient according to a distribution interval of the obtained casing external collapse load with a confidence level of (v-u)*100%. According to the method, the size of external collapse load which possibly appears at ea