Optimization Of Microwave-Magnetic Nanoparticle Synergistic Demulsification Effect

In order to improve oil recovery,major oil fields have adopted chemical drive oil recovery technology in recent years.Natural active agents make the composition of crude oil emulsions more complex and kinetically stable.The accompanying problem is that it is more difficult to separate oil and water,and the water content of oil must be less than 0.5%before transmission,so how to achieve efficient and environmentally friendly demulsification has been a major concern in the oil industry.In this paper,microwave-magnetic nanoparticle synergistic demulsification technology is used to study Xinjiang heavy oil.The project team found that the microwave and magnetic nanoparticles have significant effect in demulsification,but there are also problems such as high oil content and unclear water quality.Therefore,a new magnetic flocculant Fe₃O₄@CPAM was prepared by coating the commonly used flocculant CPAM on the surface of Fe₃O₄.And the synergistic demulsification experiments were carried out between magnetic nanoparticles and microwave before and after the modification,and the influence of microwave radiation power,radiation time and concentration of magnetic nanoparticles before and after the modification on the synergistic demulsification was studied from macroscopic perspective;The effects of microwave radiation power and radiation time on the oil droplet distribution of emulsions before and after modification,the charged properties and wettability of magnetic nanoparticles before and after modification were compared and analyzed by using biological microscope,zeta potential analyzer and contact angle measuring instrument to reveal the influence mechanism of microwave on the synergistic demulsification of magnetic nanoparticles before and after modification from a microscopic perspective.Finally,the force model of a single oil droplet under the synergistic effect of microwave-magnetic nanoparticles was established to dissect the mechanism of the effect of microwave on the synergistic demulsification of magnetic nanoparticles before and after modification from the kinetic point of view.The experimental results show that the microwave radiation parameters are too high or too low will inhibit the demulsification of magnetic nanoparticles before and after the modification,and only in the optimal range of radiation parameters,the microwave will promote the demulsification of magnetic nanoparticles before and after the modification.With the increase of magnetic nanoparticle concentration before and after the modification,the water separation of the emulsion first increases and then decreases.At a concentration of 175mg/L,there is no microwave effect,the water separation rates of Fe₃O₄@CPAM and Fe₃O₄emulsions were 42.86%and 21.34%respectively in 1h,and the demulsification rate increased nearly twice;Under the action of microwave（400W,20s）,the water separation rates of Fe₃O₄@CPAM and Fe₃O₄ emulsions were 77.38%and 55.56%respectively in 1h,and the demulsification rate increased nearly 1.5 times,and the water separation rate of Fe₃O₄@CPAM emulsion reached 95.67%at 100 min and 85℃,and the demulsification rate remained high after 7 cycles of use.The positive charge on the polymer chain of Fe₃O₄@CPAM can bridge and adsorb with multiple oil droplets at the same time,and can also form large and solid magnetic flocs and fall rapidly through the bridging and net-trapping of its own polymer chain to promote demulsification.Kinetic theory studies have found that（1）The motion velocity of oil droplets in horizontal direction is related to the radius of oil droplets,the dielectric parameter of water phase,and the interfacial tension of oil droplets.And the motion speed increases with the increase of oil droplet charge and microwave radiation power,and decreases with the increase of emulsion viscosity and oil droplet dielectric parameters.However,when the microwave radiation power is too large,the emulsion will move too fast in the horizontal direction,which will affect the aggregation of droplets and make the emulsion breaking rate decrease.The motion speed of oil droplets in the vertical direction decreases with the increase of emulsion viscosity,aqueous phase dielectric parameter,aqueous phase permeability,and oil droplet radius,and increases with the increase of oil droplet charge,dielectric constant of emulsion,magnetic permeability of emulsion,and microwave radiation power,so the emulsion breaking efficiency of emulsion increases subsequently.（2）Under the same radiation parameter of 400W and 20 s,for a single droplet,the motion velocity of the emulsion with Fe₃O₄@CPAM added in the horizontal direction is greater than that of the emulsion with Fe₃O₄ added in the microwave electromagnetic field,while the motion velocity in the vertical direction is smaller than that of the emulsion with Fe₃O₄ added in the emulsion,but the velocity in the horizontal direction is much greater than that in the vertical direction,so the coupling synergy between microwave and modified magnetic nanoparticles Fe₃O₄@CPAM is stronger,which reveals the synergistic microwave-magnetic nanoparticle emulsion breaking mechanism from the kinetic point of view.