The study on temperature field variation and phase transition law after shutdown of buried waxy crude oil pipeline

In the buried waxy crude oil pipeline, considering the change of physical properties with temperature and the latent heat of wax precipitation, based on the pipeline-soil-atmosphere coupled heat transfer, the temperature drop model after shutdown is established by apparent heat capacity method. Taking a waxy crude oil transportation pipeline in Daqing Oilfield as an example, under different initial oil temperatures, different environmental temperatures and different soil thermal conductivities, the distribution of temperature field in pipeline and soil is simulated, the influence mechanism on temperature field of these three cases is analyzed. In addition, the phase transition interface of wax precipitation in crude oil is traced, the variation law of interface position after shutdown is analyzed. This research could provide a theoretical basis for the establishment of pipeline shutdown engineering scheme.