The study of pipeline wax deposition law and pigging period for Daqing waxy crude oil

Based on the determination of pipe wall shearing stress, the wax molecular concentration gradient at pipe wall, the radial temperature gradient and the temperature drop distribution along pipeline for different flow pattern, the wax deposition model of the crude oil pipeline is established and applied to the oil pipeline between some two united stations in Daqing oilfield. According to the principle of differential pressure method, the indoor simulation experiment device is set up in order to study the wax deposition process of the crude oil pipeline. And the wax deposition experiment of oil transferring pipeline is developed which covers all the typical working conditions of the Daqing waxy crude oil pipeline. Then we analysis the suitability comparisons between the prediction results of the wax deposition model and the experimental data. The wax deposition influence of operation time on the pipeline is forecasted, and the pigging period of four months and three months for seasonal highest and lowest soil temperature is optimized respectively combined with the impact of the wax deposition thickness on pipeline axial temperature and pressure drop.