Predicting erosion in wet gas pipelines/elbows by mathematical formulations and computational fluid dynamics modeling

摘要

Sand erosion has been identified as a potential damage and failure mechanism in pipelines/elbows employed to transport gas from wells to terminals. Erosion can cause localized material loss decreasing the structural integrity of pipelines/elbows leading to failure. As a result, sand erosion has been the object of much research work in the oil and gas industry. The prediction of erosion caused by sand transported by hydrocarbons flow is a difficult task due to the large number of variables involved. At present, a great number of empirical models have been developed to predict sand erosion in smaller diameter pipelines under laboratory conditions. Therefore, such formulations generally present uncertainties for their application in larger diameter pipelines employed to transport oil and gas because there is no fundamental basis showing how the empirical formulations can be extrapolated to large diameters pipelines as most of the models have been developed on the basis of elementary laboratory experiments, which may not represent the real sand erosion conditions. Furthermore, most of the analytical/empirical models were developed for specific pipeline/elbows diameters and cannot be employed to predict erosion in different engineering structures. Hence, in the present work a computational fluid dynamic modeling strategy is proposed, which incorporated fundamental physically erosion parameters to predict erosion in larger diameter pipelines/elbows. The methodology was applied to different elbows/pipelines diameters in order to investigate how pipeline's diameter, sand production rate, and sand particles sizes affect the erosion mechanism and the erosion rate. The results showed the importance of including fluid and flow conditions, sand particles trajectory, and self-particles movement. The computational fluid dynaimcs results were compared with those obtained with the most employed empirical models to predict sand erosion in the oil and gas industry models published in the literature, and it was shown that the proposed modeling strategy can be used to predict erosion in larger diameters pipelines/elbows with good results.