Remaining Life Prediction Method Of Oilfield Oil And Gas Gathering Pipelines

Pipeline is the most secure and efficient transportation means ofoil nowadays. Liao he Oilfield as the third oilfield in China hasexplored and mined more than40years since1970. The crude oilgathering pipelines have entered aging service stage, and all of thetube wall is happening the corrosion and thinning circumstances byrestrictions on conditions of pipelines laying at that time andanticorrosion coating material of tube wall and cathodic protectionfailure after long-term operation. It is necessary to assess thesepipelines by remaining life prediction and reduce the risk of pipelineoperation and maintain the serious corrosion section.Refer to relevant document literature at home and abroad aboutthe corrosion of oil and gas buried pipeline and making on-the-spotinvestigations in Liao he Oilfield, the paper comprehensive analysesthe corrosion characteristics, molds, essences and corrosion effectelements of buried gathering pipeline. The paper expounds theprocedures of remaining life prediction, the key ingredients foraccuracy and the key point localities of prediction. The paper analysesthe corrosion district and corrosion rate determination method ofpipeline. Fully depending on the on-spot corrosion inspection data, themodel of prediction of residual life of pipeline is proposed, based onextreme value distribution method and localized corrosion developingformula. The paper establishes a improved grey model to simulate thecorrosion depth growing of tube wall based on GM(1,1) grey model,and the prediction model of tube wall corrosion state for the entirepipeline is established based on combining the improved grey model and Markov chain. The paper is established the pipeline failureprobability model in order to reduce the random factors of pipeline forremaining result and raise the accuracy. The Monte-Carlo method isapplied for simulate the pipeline failure probability and predictspipelines the remaining life based on the requested target reliability.It lists four common calculation formulas of failure pressure inresidual strength and analyses the Folias expansion coefficient andfailure pressure of formulas. In addition, the paper draws failurepressure curves of different grade pipeline steel which the tensilestrength is from small to large, and analyses the usability of fourformulas in pipeline steel. The paper is established corrosion defectdimension model based on ASME B31G-2009blow equation andregular pattern of internal pressure distribution of oil-gas gatheringpipeline. The paper uses the C language to calculate the length anddepth of corrosion area.