Sand particle erosion is a significant issue in oil and gas production. There is reasonable evidence to suggest that most wells now produce sand and that erosion accounts for about 10% to 20% of hydrocarbon release events. This is a widespread problem, affecting production both at the start of life and aging assets.

Accurate erosion predictions can be used to improve pipework design, inspection regimes, sand monitor placement and operating limits. There are various approaches to erosion prediction, ranging from simple equations to highly-sophisticated computational fluid dynamics (CFD) simulations. Each method has its advantages. Simpler calculations are generally quick and easy to use but they may be less accurate. CFD modelling can be more accurate and it can detect issues that other methods cannot, but it is a more time-consuming process.

Very little information is available on the relative merits of different erosion prediction methods. Erosion in multiphase pipe flows is a complex process; it is not fully understood, and there is significant scope to improve calculation methods. High-accuracy prediction is particularly important when a system is operating close to its tolerable erosion limit and over-estimates of erosion can lead to unnecessary design changes or overly-conservative production limits.

This work compares erosion predictions using standard erosion calculation methods (such as SPPS and DNV GL RPO501) and conventional CFD simulations against published erosion test data for bends in single and multiphase flow. Essentially, all of the methods produce similar results, with reasonable predictions for gas-sand flows, but significantly over-estimate erosion in the gas-liquid-sand flow regimes, which are more usually experienced in production systems. This comparison provides a useful measure of the overall accuracy of these methods, and hence how the results of erosion calculations should be used to steer engineering decisions.

An extension of previously published work is also included which shows that CFD simulations that explicitly model gas, liquid and sand as separate phases are as accurate as the best conventional erosion prediction methods. This approach has the advantage of being able to model complex geometries and no prior knowledge of the flow regime is required.

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