(399a) 3D Modeling of Wax Deposition in Oil/Water Stratified Flow

Wax deposition is a crucial economic issue in sub-sea oil production. Deposition modeling not only establishes scientific insight into deposition mechanisms, but also predicts deposit profiles for corrective methods such as pigging. Meanwhile, increasing off-shore drilling complicates wax deposition with multiphase flows. Previous research has been primarily focusing on single-phase wax deposition models in laminar/turbulent flow. The methods to calculate the hydrodynamics and heat/mass transfer under stratified flow are significantly different from well established single-phase flow correlations. Meanwhile, iterations on the momentum balance using computational fluid dynamics require extreme computational intensity. In this study, the first 3D deposition model in oil/water stratified flow has been developed based on the simplification of unidirectional flow in a laboratory scale flow loop. The unidirectional flow assumption helps to reduce dimensions of the calculations of the velocity profile, which is solved with successive over-relaxation (SOR) method. The 3D heat/mass transfer is solved with alternating-direction implicit (ADI) method. The model predicts that wax deposits on the upper part of the wall and reveals the effect of the addition of water. It is seen that the water phase, due to its greater heat capacity and greater thermal conductivity, has a significant impact on deposition by affecting the peak location of wax deposit, the cross-sectional averaged thickness and also in the azimuthal distribution of the deposits.