A tubular pipe adapted for transporting oil and water may be treated upon its interior surface to reduce frictional pressure of a multiphase oil/water mixture flowing through the pipe. The tubular pipe may have an interior wall and a central cavity. In some instances, the interior surface is provided with a first textured region being adapted for reducing the adhesive forces of transported oil along the interior wall. A second region upon the interior wall may be adapted for reducing the adhesive forces of water along the interior wall of the tubular pipe. In some applications, riblets may be provided upon the interior pipe wall to further reduce the frictional forces of fluid flowing through the central cavity of the pipe.