Study On Wax Deposition And Pigging Cycle Of Shunbei Pipeline

The wax deposition in the pipeline will reduce the pipeline transportation capacity,increase the power consumption,reduce the transportation efficiency,and seriously threaten the safe operation of the pipeline.The Shunbei Pipeline was put into operation in early 2020,and there are many types of crude oil.Low viscosity,high wax precipitation point.At present,the wax deposition and pigging cycle of this pipeline are not fully understood.It is of great significance to explore the wax deposition and predict the thickness of wax deposition to ensure the safe operation of the Shunbei Pipeline.The experiment tested the basic physical properties such as freezing point,density,viscosity,wax precipitation point and wax content of crude oil transported from Shunbei.90 sets of experiments were carried out in the experimental device,and the effects of different oil temperature,flow rate,oil wall temperature difference and deposition time on the deposition of six kinds of crude oil were studied.For different crude oils in the Shunbei Pipeline,a wax deposition model was established based on their basic physical properties and the thickness of the wax layer in the pigging cycle was predicted.The wax deposition model of the Shunbei crude oil can accurately predict the thickness of the wax layer along the pipeline.The model was used to explore the effects of different ground temperatures,throughput and heat transfer coefficients on the deposition rate of wax in the Shunbei crude oil.The wax deposition rate and thickness of wax layer were predicted under 36 working conditions of six kinds of crude oil in the Shunbei pipeline by using the wax deposition model of Shunbei crude oil.Under the same conditions,the deposition rate of crude oil in well 1-2 is the largest,and the deposition rate of crude oil in station TP13 is the smallest.For the same crude oil,the wax deposition from Shunbei No.1processing station to No.3 valve chamber is the most serious,and the wax deposition from the intermediate pigging station to the Yakela station is less.Taking the oil transportation outside Shunbei 1 processing station as an example,the ground temperature is 2℃,the transportation volume is 55t/h,the pipeline runs for 30 days,and the wax deposition thickness of the pipeline is 4.76mm;The thickness of pipeline wax deposition is 1.06 mm.Considering the safety of pipeline operation,the pigging cycle of the Shunbei pipeline is formulated.The pigging cycle from Shunbei 1 processing station to the intermediate pigging station is 12 days to 55 days,and the pigging cycle from the intermediate pigging station to the Yakela station is 90 days.