Residual Life Prediction Technology For Oil&Gas Corroded Pipeline

In recent years, buried oil and gas pipeline is the important link of the oil and gas production system, and the number of buried pipelines is growing. Pipelines buried underground all years which are affected by soil environment, pipeline corrosion is inevitable. Especially with the increasing of service time, the pipeline corrosion is more and more serious, and pipeline perforation cracking, leakage accident frequency is rising, which caused by pipeline corrosion failure and. This will take huge economic losses to the society. The residual life of corrosion pipe provides evidences that the corrosion of pipeline detection and maintenance. It is of great significance to ensure the safe operation of the pipeline. Therefore, in this paper, the contents of buried oil and gas pipeline corrosion residual life studying as following:(1)Oil and gas pipeline corrosion related statistical parameters includes corrosion depth, corrosion rate and the maximum corrosion depth. This paper gives the calculation methods based on different testing conditions, according to the actual need to choose the appropriate method of calculation for pipeline residual life prediction.(2)Using extreme value distribution theory and formula for local corrosion sets corrosion residual life prediction model, giving full consideration of the contingency,probability statistics method is used to estimate the possibility of the entire pipeline maximum corrosion depth and predict pipeline residual life. It estimates model parameters by using MCMC, avoiding the error of the general linear fitting for parameter, ensure the accuracy of the prediction results.(3)Using reliability theory builds pipeline failure model to predict pipeline residuallife, the model fully considers the various random factors on the corrosion, It simulates pipeline failure probability by MCS to predict uniform corrosion residual life.(4)According to the theory of extreme value distribution and reliability model predicted results, considering safety and economy, as an example, it takes a Liaoning pipeline, applying these two models to predict its residual life, 19.95 years and 20.63 years, which indicates that the predict result is correct and reasonable. combined with the two models, is proposed for the oilfield the optimal inspection maintenance strategy,which operation cost is the least, the next detection interval time is 11 years.