Wax Deposition Modeling with Considerations of Non-Newtonian Characteristics: Application on Field-Scale Pipeline

Wax removal by pigging is costly in sub-sea oil production. Cost-effective scheduling of pigging can be achieved based on the deposition rate predicted by wax deposition models. Conventional wax deposition models predict wax deposition rates on the basis of Newtonian fluid mechanics. Such an approach can become invalid for highly waxy crude oils with non Newtonian rheology. In this investigation, different simulation techniques, including large eddy simulation, Reynolds-averaged Naiver Stokes equations, and the law of the wall, were applied to model non-Newtonian pipe flow. It was discovered that the law of the wall method is the best method to calculate the velocity profile, shear stress and the turbulent momentum diffusivity in turbulent non-Newtonian pipe flow of waxy oil. An enhanced wax deposition model considering the non-Newtonian characteristics of waxy oil using the law of the wall method was developed and applied to predict wax deposition rates in a field scale pipeline.