Entrained sand particles in the oil/gas production fluid impinge on the inner surfaces of the pipes, fittings, and valves that result in solid particle erosion. Even in situations when sand control means are utilized such as gravel packing and sand screens, small sand particles can plug sand screens promoting higher flow velocities through other portions of sand screens causing failure of sand screens and allowing sand production.
Predicting solid particle erosion in multiphase flow is a complex task due to existence of different flow patterns. The existence of different flow patterns and sand and liquid holdup in vertical and horizontal pipes means that a unique erosion model has to be developed for each flow regime if the model has to account for the number and velocity of impacting particles. In current efforts at the Erosion/Corrosion Research Center, local void fraction measurements by Wire Mesh Sensors (WMS) and Computational Fluid Dynamics (CFD) simulations of multiphase flows are employed to aid in predicting gas-liquid-sand velocities in multiphase flows. For the first time, CFD is used to compute erosion rates in multiphase flow. CFD is a very useful tool for predicting details of multiphase flow. However, CFD results must be validated by grid refinement studies and by comparison to experimental data.
Erosion experiments are also conducted on elbows in a 3-inch and 4-inch large scale multiphase flow loop with gas, liquid and sand flowing in vertical and horizontal test sections. Based on the experimental data and simulations for different flow regimes including slug, wet gas and annular flow a mechanistic model is being developed to predict solid particle erosion rates of elbows in multiphase flow.