Application of fuzzy comprehensive evaluation on borehole collapse risk

According to the high uncertainty and vagueness of wellbore stability issue during drilling, the methods of analytical hierarchy process and fuzzy comprehensive evaluation are applied to borehole collapse risk prediction, based on the sufficient analysis on all the factors affecting borehole stability. The analytical hierarchy process method is used to determine the weight coefficients of each factor, and the fuzzy comprehensive evaluation method is taken to establish risk prediction model for borehole collapse. A set of quantitative analyse method is formed to assess the borehole collapse risk, which supplies effective risk control for the potential borehole collapse risk. The model is used in Well YB-22 and the results show that the method is feasible to forecast well collapse risk.