基于可拓理论的油井管螺纹密封性评价方法

Evaluation of OCTG Thread Tightness Based on Extension Theory

为了使油井管螺纹密封性评价结果更加准确全面,运用可拓理论建立油井管螺纹安全评价的物元模型,将其密封性等级、评价指标、指标值域结合为一体,构建评价指标体系和评价标准,通过对指标进行量化和归一化处理,确定待评物元的经典域和节域;利用可拓理论的关联函数计算评价指标对密封性等级的关联系数,引入改进的层次分析法计算指标权重,根据级别变量特征值判定油井管螺纹的密封性等级,对5根油井管的密封性进行了危险等级的评价,评价结果与实际情况相符,验证了评价方法的正确性,为油井管螺纹密封性评价提供了一种有效的新途径。

In order to make the evaluation results of OCTG thread sealing more accurate and comprehensive,the matter-element model of OCTG thread safety evaluation is established by using the extension theory.The sealing grade,evaluation index and index range are combined to construct the evaluation index system and evaluation standard.The classical domain and section domain of the matter-element to be evaluated are determined by quantifying and normalizing the indexes.The correlation coefficient of the evaluation index against the sealing grade is calculated by using the correlation function of extension theory.The improved Analytic Hierarchy Process(AHP)is introduced to calculate the index weight.The sealing grade of OCTG thread is determined according to the eigenvalue of the grade variable.The sealing grade of five tubular strings is evaluated according to the risk grade.The evaluation results are consistent with the actual situation,which verifies the correctness of the evaluation method.It provides a new effective way to evaluate the tightness of OCTG thread.