Calculation of wax content and tracking of PPD-added oil head for waxy crude oil pipeline

During transportation of waxy crude oil, wax precipitation may lead to pipeline blockage and difficult re-start after shutdown. To address this problem, after analysis of operating parameters, hydraulic friction formula transformation and SPS modeling are made to derive the content of non-effluents mainly consisting of wax precipitated along a long-distance pipeline. Considering the filter stoppage and lower pour point of PPD-added oil head when it arrives at terminal station, actual volume of non-effluents is obtained. Both results are compared, indicating that the calculated wax content tallies with the actual wax content, so the model meets the requirements basically. Because of large difference of viscosity between Chad high pour point oil with PPD and without PPD, an PPD-added oil head tracking method is proposed according to pressure drop variation between valve chambers/stations. The method is used to estimate the approximate location of PPD-added oil head, providing a reference to the determination when and how much depressant is added in high pour point and high waxy crude oil pipeline.