In the water lubricated pipeline transportation of heavy oil and bitumen, a thin oil film typically coats the pipe wall, which is often referred to as ‘wall fouling'. A detailed study of the hydrodynamic effects of wall fouling is critical to the design and operation of oil/water pipelines, as the viscous layer can increase the pipeline pressure loss (and pumping power requirements) by 15 times or more.
In this study a parametric investigation of the hydrodynamic effects caused by the wall coating of viscous oil was conducted. A custom-built rectangular flow cell was used as the principal apparatus. The controlled parameters include the thickness of the wall coating layer, oil viscosity and water flow rate. For each test condition, the pressure loss across the test section was measured and the hydrodynamic effect of the wall coating on the pressure loss was determined. A novel procedure using CFD simulations was developed to determine the hydrodynamic roughness. The procedure was also applied for a set of pipeloop test results published elsewhere. The effects of wall coating thickness and water flowrate on the hydrodynamic roughness were evaluated. The most significant outcome of this analysis is a new correlation for the hydrodynamic roughness produced by a wall-coating layer of viscous oil.
The knowledge gained from the current research will be beneficial for designing, operating and troubleshooting pipeline systems in which a viscous wall coating is produced, including water lubricated bitumen transport in the oil sands industry, CHOPS and SAGD surface production/transport lines. The methodology can also be extended to the analysis of any unknown hydrodynamic roughness.