A study on friction loss and hold-up ratio in the water-lubricated pipeline transportation of heavy oil

CORE ANNULAR FLOW (CAF) is an economically efficient and environmentally sustainable technology for transporting heavy oil and bitumen, especially compared with conventional methods such as truck hauling, dilution, and heating. In CAF, heavy oil forms the core of the flow and a water sheath encloses this core by forming a continuous layer on the pipe wall. Power requirements are orders of magnitude lower than those associated with the flow of heavy oil alone. In fact, the CAF pressure loss is comparable to that for transporting only water. One of the major obstacles to the largescale implementation of this technology is the unavailability of a reliable model for the frictional pressure loss. In this work, a CFD-based modelling methodology is validated and analysed with respect to the measured values of pressure losses in a CAF pipeline. Another subject of interest in the field of CAF hydraulics is modelling the hold-up, which simply refers to the in situ volume fraction. Most of the previous works did not focus on the underlying physics of the phenomenon. As a result, the available models do not take into account the process parameters such as mass flow rate, viscosity, and density. A new modelling approach is introduced in this work that addresses the actual physics of hold-up.The current study helps to understand the hydrodynamics that govern friction losses in CAF pipelines.