Experimental Study On Viscosity Reduction By Microwave Heating Assisted By Nano-Catalyst

Chinese heavy oil resources are abundant,and the full exploitation and utilization of heavy oil resources are of great significance for ensuring the rapid,steady and effective development of Chinese economy.However,its high content of resin and asphaltene,which causes high viscosity and poor fluidity at room temperature,becomes the main problems restricting heavy oil exploitation and gathering.At present,the common technical methods of heavy oil pipeline transportation are heating,emulsification and dilution transportation,which have the disadvantages of high energy consumption and poor stability.In this paper,nano-catalyst and microwave synergistic viscosity-reducing methods are applied.Firstly,single-factor experiment is used to screen microwave power,temperature and nano-catalyst concentration to determine the optimal parameter range.In order to explore the interactive relationship and the significance of their influences,response surface experimental design method was used to carry out regression analysis of the data and optimize parameter values.It is found that temperature has the most significant effect on viscosity reduction under the single factor.Under the interaction,temperature and catalyst concentration,power and catalyst concentration had significant interaction.The optimum processing parameters are microwave power of 600W,catalyst concentration of 0.5%,temperature of 72.38?,and the predicted viscosity reduction rate at 42.7%.The viscosity reduction rate of the model is 37.65%,and the difference between the model and the predicted value is 5.05%,further proving the reliability of the model optimization results.In order to analyze the stability of viscosity reduction,water-in-oil emulsions of 10%,20%,30%and 40%were prepared by S-80.It is found that the emulsions with 30%and 40%water content have a better viscosity reduction stability,and the viscosity reduction rates remain 74.28%and 85.5%after 10 days of rest.At the same time,In order to compare the effect of nano-catalyst assisted microwave on viscosity reduction,nano-catalyst assisted ultrasound and water bath heating were selected for experiments.Because of the limitation of experimental conditions,the Slotting ultrasonic wave was used.It is found that there is no interaction between the parameters of ultrasonic wave and nano-catalyst.The results of comparison between water bath and microwave show that microwave has a better viscosity reduction effect under the combined action of thermal and non-thermal effects of microwave.Finally,In order to further analyze the mechanism of viscosity reduction,the oil samples were subjected to four-component separation,elemental analysis,infrared spectroscopy and full two-dimensional gas chromatography using modern testing methods.The original oil samples,oil samples treated by microwave,oil samples tread by nano-catalyst and oil samples treated by nano-catalyst assisted microwave were tested microscopically.It is found that the total amount of resin and asphaltene decreased from44.68%to 26.73,34.7%and 18.59%singly,which increases the saturated hydrocarbons and aromatic hydrocarbons in light components.The sulfur content decreases from 1.917%to 1.56%,1.09%and 0,the nitrogen content decreases from 0.536%to 0.427%,0.502%and 0.389%.Not only the relative concentration of functional groups decreases,but also the number of isoparaffins and aromatic rings and heterocycles decreases as well.The results of two-dimensional analysis shows that the content of PAHs and macromolecular compounds decreases,and the total amount of C₃₀-C₄₀ decreases from 1.88%to 1.28%,1.164%and 0.89%,respectively.The percentage of n-alkanes increases,which further explains the reason of viscosity reduction.