| Waxy crude oil accounts for more than 80% in China.Waxy crude oil has high pour point and complex rheological properties.In order to ensure the safe and economic operation of waxy crude oil storage and transportation system,technical measures must be taken to improve its fluidity.The magnetic treatment technology can reduce the viscosity of waxy crude oil and improve its fluidity in gathering pipeline.In this paper,static and dynamic magnetic treatment experiments were carried out to study the viscosity changes of waxy crude oil before and after magnetic treatment,and the effects of different magnetic treatment conditions on the viscosity of waxy crude oil were analyzed.The structural changes of waxy crystals and asphaltenes were analyzed through magnetic treatment microscopic observation experiments,and the reasons for viscosity reduction of waxy crude oil treated by magnetic treatment were explored.The self-developed static magnetic treatment device consists of N52 Nd Fe B permanent magnet,austenitic stainless steel 1Cr18Ni9 Ti material and constant temperature water bath.The magnetic field intensity ranges from 0 to 300 m T and the magnetic treatment temperature ranges from 0 to 75 ?.The self-developed dynamic magnetic treatment device consists of crude oil storage tank,main section,magnetic treatment section and control cabinet.The magnetic field intensity ranges from 0 to 300 m T,and the magnetic treatment temperature ranges from 25 to 80 ?.The viscosity reduction of waxy crude oil increases first and then decreases with the increase of magnetic treatment temperature,increases first and then decreases with the increase of magnetic treatment intensity,increases first and then remains unchanged with the increase of magnetic treatment time,and decreases with the increase of flow rate.For the oil samples,the optimum magnetic treatment temperature is 6 ? higher than wax precipitation temperature,the optimum magnetic field intensity is 150 m T,the optimum magnetic treatment time is 1 min,and the optimum flow rate is 0.1 m/s.The effect of magnetic treatment temperature on viscosity reduction rate is the greatest,followed by magnetic treatment intensity and magnetic treatment time,and the effect of flow rate is the smallest.Microscopic observation of magnetic treatment shows that the magnetic field can aggregate wax molecules and disperse asphaltene.The increase of the proportion of large wax crystals in waxy crude oil increases the flow area of liquid hydrocarbons,which reduces the viscosity of waxy crude oil.The increase of dispersed asphaltene inhibits the precipitation of waxy crystals and decreases the amount of aggregated asphaltene,which reduces the wax crystallization core and the cumulative wax precipitation,thus reducing the viscosity of waxy crude oil and improving its fluidity. |
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