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Tang Y.,Southwest Petroleum University | Liu Q.Y.,Southwest Petroleum University | Liu Q.Y.,Chengdu University of Technology | Xie C.,Southwest Petroleum University | Chen S.W.,Quality Supervision and Testing Research Institute
Engineering Failure Analysis | Year: 2015

Taking a double ram blowout preventer (Ram BOP) 2FZ54-105 as an example, we have analyzed the stress distribution rule and the stress concentration regions of its body under the rated working conditions (RWC) and the hydrostatic test pressure (HTP) with the finite element analysis (FEA) methods and the stress testing experiment (STE) methods. And then it was found that the simulation results of the FEA were essentially consistent with the STEs through the comparative analysis, and the feasibility and accuracy of these two methods are corroborated each other. Moreover, we confirm that the body strength meets the design requirements and using conditions by combining with the analysis results of two methods. Finally, the stress concentration regions of inner and outer surfaces of the body were summarized and gained based on the comprehensive analysis of all cases. These methods and results in this study can provide references for structure modified design of the body and guide on-site maintenance and safety evaluation of the Ram BOP in service. © 2015 Elsevier Ltd.

Tang Y.,Southwest Petroleum University | Jing J.J.,Quality Supervision and Testing Research Institute | Yang Y.,Southwest Petroleum University | Xie C.,Southwest Petroleum University
Mathematical Problems in Engineering | Year: 2015

The wearing parts of a system have a very high failure frequency, making it necessary to carry out continual functional inspections and maintenance to protect the system from unscheduled downtime. This allows for the collection of a large amount of maintenance data. Taking the unique characteristics of the wearing parts into consideration, we establish their respective delay time models in ideal inspection cases and nonideal inspection cases. The model parameters are estimated entirely using the collected maintenance data. Then, a likelihood function of all renewal events is derived based on their occurring probability functions, and the model parameters are calculated with the maximum likelihood function method, which is solved by the CRM. Finally, using two wearing parts from the oil and gas drilling industry as examples - the filter element and the blowout preventer rubber core - the parameters of the distribution function of the initial failure time and the delay time for each example are estimated, and their distribution functions are obtained. Such parameter estimation based on objective data will contribute to the optimization of the reasonable function inspection interval and will also provide some theoretical models to support the integrity management of equipment or systems. © 2015 Y. Tang et al.

Tang Y.,Southwest Petroleum University | Zou Z.,Southwest Petroleum University | Jing J.,Quality Supervision and Testing Research Institute | Zhang Z.,Quality Supervision and Testing Research Institute | Xie C.,Southwest Petroleum University
Journal of Natural Gas Science and Engineering | Year: 2015

There are few scientific maintenance decision-making methods in current maintenance and management of drilling and production equipment (DPE). Conventional methods have some conspicuous deficiencies and shortcomings, for example, unreasonable maintenance methods, surplus or insufficient maintenance, exorbitant maintenance costs and increasing failure frequency, which have caught a great influence to production safety and economic cost in the oil and gas exploitation process. In this study, a framework for making maintenance decisions was presented in order to improve the maintenance and management of the DPE. First, eight evaluation indexes and their scoring criteria were defined to quantify subjective evaluation of importance level of the DPE. Then, a linear weighted mathematical model was presented to calculate importance level value and a weight computing method of each evaluation index was put forward based on the Analytic Hierarchy Process (AHP). And the subjective effects were eliminated with Monte Carlo Simulation (MCS) in the scoring process. Next, maintenance decision-making trees (MDMTs) for the DPE were set up by reference to the logic decision tree of reliability-centred maintenance (RCM). Finally, feasibility of the framework was verified by testing a well control system in Tarim Oilfield. Therefore, the framework for making maintenance decisions can provide reasonable maintenance methods and achieve scientific maintenance and management for the DPE. © 2015 Elsevier B.V.

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