Application of core annular flow for oil transportation in different pipe configurations using computational fluid dynamics

Abstract

The application of Core Annular Flow (CAF) has become an interesting solution in transporting heavy oil through pipeline because of its energy reduction and cost efficiency. Current study conducted a 3D computational fluid dynamic (CFD) to simulate CAF of oil-water in horizontal T- and Y-pipe junctions with two types of oil characteristic i.e., oil as Newtonian fluid and oil as non-Newtonian Carreau Fluid. The 2k factorial statistical experimental design was applied to investigate the effect of geometry on the flow performance. Eight cases were run with different diameter combinations and junction angle. The most attractive design was measured by the high value of oil holdup with small average values of pressure gradient and pressure standard deviation. The simulation result showed the stable CAF along the upstream region but then broke up when passing the intersection. A strategy to recover the stability of CAF after passing the intersection area of a T-pipe without interrupting the flow process was also proposed specifically for T50-50 (T-pipe with inlet and outlet diameter of 50 mm) as the most desired design for water-oil as non-Newtonian Carreau Fluid case. An additional water insertion was introduced at the intersection point to support the recovery of CAF structure by suppressing fouling. The proposed design showed significant improvement of CAF consistency for downstream region until pipe outlets. Energy evaluation was also has been conducted and it was estimated that CAF in T50-50 was able to reduce the pressure drop to more than 90% compared to transportation without lubrication. In addition, the cost of power consumption can be saved to more than 80% than single phase oil transportation. A scaled-up pipe size simulation was also completed to 10 times bigger dimension. More consistence result of lubricated flow was shown by bigger dimension pipe.