The Safety Assessment Of Oil Derrick Based On The Optimization Of Multi Evaluation Index

The oil derrick is the key of the whole bearing equipment of oil drilling rig system, its main use for bearing loads that drilling, casing and other work produced, its work safety is critical. In this paper, the two main theories of the oil derrick safety assessment—reliability theory, stability and strength theory was introduced, put forward the oil derrick reliability and stability evaluation index, used the reliability, stability evaluation index of safety evaluation for a type of derrick for examples differently. the equivalent treatment for oil derrick damage defects was studied; Analyzed the evaluation index of oil derrick damage and load sensitivity, and the applied the fuzzy comprehensive evaluation of integral method to optimize the oil derrick safety evaluation index. At last, estimated the safety of oil derrick based on multi index optimization of JJ220/42-K laboratory model derrick containing corrosion and initial bending, determined the safety bearing capacity by comprehensive analysis.Considering the random effect of derrick loading, material properties and structural geometry size and other factors, put forward the method of oil derrick evaluation that based on random reliability for safety evaluation index, established the oil derrick model, work out the file compilation flow analysis of derrick.The evaluation method of oil derrick strength, stability, the overall stability of the column was introduced, the overall stability and the pillar stability of derrick evaluation index wan recommended, and the numerical stability, the overall stability of derrick post index was calculated. The basic process of the oil derrick security assessment based on strength, stability was provided, and then conducted a certain type of oil derrick’s Stability evaluation.The common defects of oil derrick damage- corrosion and initial bending was analyzed, the function relationship of derricks poles with equivalent sectional area of corrosion depth was deduced; According to the site of initial bending deformation characteristics of oil derrick, and simplified it as sine wave curve, then conversion coefficient of different deformation was obtained. The sensitivity of oil derrick reliability index, the column stability index and stability index with the change of load, corrosion and initial bending of derrick was studied, then the model of safety evaluation index optimization of oil derrick was established by using the fuzzy comprehensive evaluation method.For example to evaluate the safety of the JJ220/42-K laboratory model derrick with damage. The damage characteristics of oil derrick was analyzed, evaluation index selected, and then safety assessment was estimated by calculation, the safety bearing capacity of the derrick under these conditions was obtained. Analysis shows that the method proposed in this paper is correct.