Selection of PDC Bit by Using Improved Fuzzy Comprehensive Evaluation Method

In order to overcome the disadvantage of strong subjectivity and possible information loss by the traditional fuzzy comprehensive evaluation method to optimize PDC bits,this paper advanced the improved comprehensive evaluation method.Using analytic hierarchy process to calculate weight set to overcome the defect of strong subjective factors in original method to determine weight set,the method adopts weighted method for fuzzy operation,taking the effects of all factors into comprehensive consideration.With this improved method,the PDC bits for a block in Dagang Oilfield were selected,the membership degree of the bit which has the longest drilling footage and highest penetration rate is less than that of bits which consider the various factors comprehensively,indicating that in optimization of PDC bits,all factors,rather than the footage and penetration rate alone,should be considered comprehensively.Field application showed that the improved fuzzy comprehensive evaluation method had high feasibility,and the PDC bits selected by it had high adaptability to formation.