Corrosion Forecast of Offshore Oil and Gas Pipelines Based on Frechet Distribution

Frechet extreme distribution was used to establish for the maximum depth of corrosion pit, the values of parameters in the forecast model were estimated using Markov chain Monte Carlo (MCMC) method. By combining with the evaluation method of corrosion damage of steel pipelines and Markov chain model, forecasted maximum corrosion depths of pipelines, the maximum probability state of pipeline wall corrosion was analyzed and forecasted, so that the scientific evaluation and forecast on corrosion status and operation condition of offshore oil and gas pipelines could be realized. The results show that the corrosion rate will be accelerated when the pipeline enters the third state, when the pipeline runs to the tenth years, it will need to be replaced with a new tube. The combination model can well forecast the maximum depth of corrosion pit and the corrosion situation of offshore oil and gas pipelines, and provide a scientific basis for maintenance, repair and detection of the offshore pipelines.