Determination of pigging circle for heated waxy oil pipeline under different flow states

As the temperature reduces in heated waxy oil pipeline, wax crystal continues to precipitate. The wax sediment reduces the pipeline transmission capacity, increases the friction resistance and raises power consumption. To restore the pipeline transmission capacity and ensure the safety operation of pipeline, regular wax removing is needed. Taking the transition of flow states into consideration, different formulas of temperature and friction drop under different flow states are applied. Wax precipitation and running cost corresponding to different flow states are obtained, and the best pigging circle is determined. Finally, the effect of different flow states on temperature drop, pressure drop and pigging circle of heated waxy oil pipeline is analyzed.