Abstract
Internal pipeline corrosion is a serious concern for transportation pipelines in the oil and gas industry. Water wetting is an important aspect of internal corrosion of mild steel pipelines, since the steel will not corrode unless the water is in direct contact with it. A water wetting model considering oil and water properties, flow rates, water cut, etc., has been proposed previously. This model showed good agreement between experimental results and the water wetting predictions for a water-paraffinic model oil system. However, for crude oil systems, this model over-predicted water wetting leading to overestimation of corrosion in realistic flow system. Here, a new, improved water wetting prediction model is proposed. The new model includes the effect of the steel surface-fluid interactions in order to calculate the transition between oil and water wetting in oil-water two-phase flow, in addition to considering the interaction between the bulk turbulence and the surface tension, as was done in the original model. The new model significantly improves the prediction of the critical oil phase velocity required for full water entrainment of water, when compared to the original model. The new model has been verified with results from large scale (0.1 m ID) multiphase flow loop experiments as well as with results obtained using a doughnut cell - which is a benchtop multiphase flow apparatus. The verification included data obtained with different crude oils as well as with a model oil containing different surface active chemical.
