Study Of Combination Effects Of Mixing Heavy Oil And Adding Pour Point Depressant On Waxy Crude Oil

The Shixi-Karamay Pipeline of Xinjiang Oilfield used LS-1 pour point depressant(PPD)in the winter of 2017.The pipeline ran steadily and safely last year,but the gel point of the crude oil in the pipeline rised sharply in this year early.So the pour point depressant for both Shixi-Karamay Pipeline and Shinan No.21 Pipeline should be rescreened.If a certain proportion of heavy oil can be mixed into the pipeline,the pipeline will run more steadily than just adding pour point depressant.The experiments for feasibility and stability of the program were conducted in the laboratory.In this paper,the stability of the pour point depressing effect in Shixi-Karamay Pipeline and Shinan No.21 Pipeline are evaluated through indoor evaluation experiments.The program just adding PPDs in winter are simulated through pipeline transportation simulation experiment and two kinds of PPD are screened.In October 2018,the pipelines are subjected to the field experiments of adding PPDs and the operation plans in winter are determined.The experimental results show the outlet temperature of Shixi station should be controlled at 55°C or higher and the dosage should be controlled at 30 ppm or more,when adding the PPD to the Shixi-Karamay pipeline in winter.There is no need to use the furnace at the intermediate station during the winter.The indoor experiments of mixing heavy oil and waxy crude oil are conducted.The experimental results show when the mixing ratio is 1:1 and heated to 55?,the gel point is measured as low as-8?,which can provide theoretical support for oil mixing transportation.If same dosage of PPDs are added in mixed oil,the gel point will be as low as-10?.Indoor evaluation experiments are conducted to evaluate the stability of the mixed oil used and not used PPDs.The experimental results show when PPD treated oil mix a certain proportion of heavy oil and measure the gel point at the same condition of Zongzhan station,negative effects on flowability of oil brought by oil temperature rising and shearing can be inhibited slightly.The method can help we get the true gel point of the crude oil in the pipeline in actual production of oilfield.The design throughput is 2 million tons per year,while the current throughput is only 1 million tons per year.So transporting mixed oil can also improve efficiency of the pipeline.