Study On Mechanism Of Heavy Oil Upgrading And EOR With Nano-catalyst Assisted Microwave

Heavy oil reservoirs are widely distributed in our country with abundant reserves.Most heavy oil reservoirs have good porosity and permeability,but their high viscosity and poor mobility lead to low recovery of heavy oil.In this paper,nano-catalyst assisted microwave heavy oil upgrading and enhanced oil recovery technology was proposed,which is very important for the development of heavy oil.Based on the investigation of microwave and nano-catalyst technology,the effect of nanocatalysts on the heat utilization efficiency of heavy oil was studied with heavy oil heat transfer experiments and microwave heating experiments.The related mechanisms were analyzed in three aspects: nano-catalyst enhancing the heat transfer process of heavy oil,nano-catalyst improving the ability of absorbing microwave of heavy oil,and formation of local high temperature region in microwave envrionment.The upgrading and viscosity reduction effects of nano-catalyst assisted microwave technology were studied with microwave heating experiments.Besides,the effects of water,hydrogen donor,nano-catalyst,and microwave parameters on the viscosity reduction of heavy oil were analyzed,and the viscosity recovery phenomenon was investigated.Through the microwave heavy oil gravity drainage experiment,the mechanism of nano-catalyst assisted microwave technology enhancing heavy oil recovery was studied,and the effects of water cut,nano-catalyst,and microwave power on oil drainage production were analyzed.The results showed that the nano-catalyst can improve the heat transfer capacity of heavy oil.The surface temperature of heavy oil sample that was added 1wt% nano-magnetic iron oxide catalyst increased by 22.5% in comparison with the original one,under identical experimental conditions.The nano-catalyst can improve the microwave absorbing ability of heavy oil,and the heating rate of the heavy oil in the microwave is increased by 60.6% with 0.6wt% nano-magnetic iron oxide catalyst.The nano-catalyst facilitates the formation of local high temperature area during microwave heating,which provides the condition for heavy oil cracking.The nano-catalyst assisted microwave heating heavy oil method can effectively improve the viscosity reduction of heavy oil,reduce the asphaltene content from 12% to 2%.The optimal experimental conditions are as below: the concentration of tetrahydronaphthalene was 2-5 wt%,nano-scale concentration of magnetic iron oxide catalyst was 0.5 wt%,the optimal microwave heating time was 50-60 min,and the optimal microwave power was 539 W.The method has the viscosity recovery problem,and the final viscosity reduction rate is stabilized at 50% after recovery.The mechanisms of nano-catalyst assisted microwave techonology on enhancing oil recovery were proposed.On one hand,nano-catalyst can improve the microwave absorbing ability of heavy oil and accelerate the heating rate of heavy oil.On the other hand,the nano-catalyst catalyzes the hydrocracking reaction of heavy components in heavy oil under microwave heating environment.This reaction upgrades the heavy oil and reduces the viscosity of the heavy oil,which speeds up the drainage production.