Characteristics of oil/water two-phase flow in horizontal pipelines

The flow patterns and frictional pressure drops of oil-water two-phase flow in horizontal steel and Plexiglas pipes of 40 mm I.D. were experimentally studied. The investigation shows that the phase inversion from water-in-oil (W/O) to oil-in-water (O/W) dispersed flow occurs about at the water cut of 0.4. With the increase of water cut, the frictional pressure drop decreases rapidly, once above 0.4, the pressure drop changes slowly. The frictional pressure drop of oil/water two-phase flow is affected by water cut, wettability of fluid to pipe wall, pipe roughness and flow rates. When in the state of O/W, the frictional pressure drop of oil-water flow in steel pipe is greater than that in Plexiglas pipe, while in W/O, the frictional pressure drop in Plexiglas pipe is greater. Therefore, when applying the experimental data and results tested in Plexiglas pipe in laboratory to the actual engineering pipelines, the effects of wettability of oil to pipe wall must be taken into consideration, specially at the state of W/O and low mixture flow rate.