Experimental Studies of Water Wetting in Large-Diameter Horizontal Oil/Water Pipe Flows

Internal pipeline corrosion in oil production and transportation is always associated with the presence of water, and the likelihood of corrosion generally increases with the volume fraction of water. When the walls of the pipeline are wetted with oil no corrosion is possible. Highly turbulent flow was associated with negligible corrosion due to water entrainment by the flowing oil, whereas low flow rates or intermittent flow have been associated with corrosive conditions. In this study, four advanced techniques (wall conductance probes, corrosion monitoring, wall sampling and flow pattern visualization) were used to determine phase wetting on the internal wall of pipe at different superficial oil and water velocities in the large diameter oil-water horizontal flow. Four flow patterns were observed: stratified flow, stratified flow with mixed layer, semi-dispersed and dispersed flows. Three types of phase wetting regimes (water wetting, intermittent wetting and oil wetting) were determined. A phase wetting map was obtained based on the overlapping information from these techniques. It is clear that the critical oil velocity of water entrainment increases with increasing input water cuts. The water cut has a significant effect on the critical oil velocity for water entrainment. Based on the results of corrosion monitoring, it is also found out that no corrosion occurs under oil wetting. At same superficial oil velocity, corrosion rate under water wetting is much higher than that under intermittent wetting.