SMOOTHPIPE: Applied Surface Technology for Multiphase Pipelines

Pressure drop along the pipeline is the main obstacle to transportation of unprocessed or partly processed wellstream over long distances. Several parameters contribute to the pressure drop, e.g. liquid hold-up, precipitations, gas-liquid surface drag for ces and surface roughness. The project will focus on how pressure drop can be reduced by coating the inside of the pipeline. Precipitation may decrease the effective internal diameter of the pipe, as well as increasing surface roughness. The most impor tant precipitants are wax, hydrates or scale, depending on properties of the fluid, pressure and temperature. Wax deposition will be studied in this project. Deposition is expected to depend on a balance of the particle-wall adhesion force and hydrodynami c forces and phoretic forces. A thorough knowledge of these mechanisms is vital input to the design of an effective non-stick coating. Wax deposition is limited to the cooling zone of the pipeline. Hence, application of a non-stick coating in this part of the pipe will decrease the problem. Since a limited area will be treated, highly advanced coatings may be used. Recent developments in nanotechnology will be utilised to design such a coating. Applying a protective coating inside the pipeline will pre vent corrosion and decrease surface roughness, which again may decrease pressure drop. Wetting properties of the coating will affect liquid films on the pipe wall, which in turn affect pressure drop due to drag forces between gas and liquid phases. Whethe r the surface is wetted by water or hydrocarbons may also have a significant effect on pressure drop. The purpose of applying a coating is to add new functionality of the surface. However, in order for the effect to be lasting the coating must be dura ble in the environment it will be exposed. Hence, obtaining a thorough understanding of coating degradation mechanisms, expected lifetime and consequences is of vital importance.