Reynolds Number Influence on Wax Deposition

Wax deposition is a phenomenon present in oil production systems (mainly in deep water due to the low temperatures), which consists in the adhesion of solids fractions of hydrocarbon to tubing and lines, reducing the area opened to flow until eventually being completely blocked. The comprehension of the mechanisms that influences in the deposition has not yet been fully achieved. Given the relevance of this kind of system in new fields' development and the absence of a theory able to explain the deposit's evolution and characteristics, the production limitation caused by this phenomenon is one of the main issues in flow assurance. The flow regime in production lines can vary from laminar to turbulent. Therefore, the influence of the Reynolds number in the deposition phenomena is investigated. To represent the turbulence, a two equation κ-ω turbulence model coupled to the enthalpy-porosity model, where the deposit is a porous media, was developed. From a thermodynamic equilibrium, the species that comes out of solution are determined while their concentration distribution is determined by each molar conservation equation. The conservations equations were solved with the finite volume method, employing the Power-law and implicit Euler schemes to handle the spatial and temporal discretization. Comparison with controlled experiments in an annular section was performed with reasonable agreement for the deposition thickness, especially for steady state. The deposit's thickness reduction with the Reynold number increase was verified. The influence of the flow regime from laminar to turbulent is examined through the deposit thickness, velocity, temperature and species fields.