Experimental Study on Heavy Oil Drag Reduction in Horizontal Pipelines by Water Annular Conveying

Transportation of heavy oil by the so-called water-ring technique is a very promising method by which pressure drop and pollution can be significantly reduced. Dedicated experiments have been carried out by changing the phase's density, viscosity, velocity and interfacial tension to systematically analyze the characteristics of the water ring. On the basis of such experimental data, a mathematical model for pressure drop prediction has been introduced. This research shows that as long as the density of oil and water remains the same, a concentric water ring can effectively be formed. In such conditions, the oil-water viscosity difference has little effect on the shape of water ring, and it only affects the pressure drop. The greater the viscosity of heavy oil, the smaller the pressure drop of the oil-water ring transportation system. The influence of phases' interfacial tension on the characteristics and pressure drop of the heavy oil-water ring can be considered negligible. The pressure drop prediction model introduced on the basis of the Buckingham's principle provides values in good agreement (95%) with the experimental data.