Lubricated Transport of Heavy Oil Investigated by CFD

Heavy oil-water flow in horizontal pipes is studied by computational fluid dynamics (CFD) using the commercial CFD software ANSYS Fluent. Water-lubricated transport of heavy viscous oil “core annular flow” (CAF) is a promising technique for transporting heavy oil via horizontal pipes. This work investigates CAF numerically, using Large Eddy Simulation (LES). Its objectives are to gain an improved understanding of the behaviour of heavy oil flow through turbulent CAF in horizontal pipes and to examine the effectiveness and applicability of the LES. Heavy oil-water-air three-phase flow and heavy oil-water two-phase flow in horizontal pipe are simulated using ANSYS Fluent 16.2. A relationship between the appearance of lubricated flow and the water inflow volume fraction is identified and related to oil fouling on the pipe wall. The rise in frictional loss is characterised and closely related to oil fouling on the pipe wall from the axial pressure gradient. The model predicts that fouling can be minimized by increasing the water flow. It is found that the water phase affects the behaviour of the CAF and the axial pressure drop. It was observed that greater stability in the CAF leads to a reduction in the axial pressure drop to a value close to that for a water flow. The impact of temperature on three-phase heavy oil-water- air flow in a horizontal pipe is affected by gravity. It has been observed that the air phase and changes in the temperature influence the stability of annular flow and the axial pressure drop. Some results made during this study are validated with reference experimental and numerical results from literature and shown to be in reasonably good agreement.