Evaluation Of Catalytic Upgrading Effect Of Hydrogen Supply In Heavy Oil Combustion And Analysis Of Viscosity Reduction Mechanism

In-situ combustion is an efficient heavy oil recovery method.By injecting air to ignite the oil layer and using the cracked coke in the oil layer as fuel,the combustion front is kept burning continuously,and the recovery efficiency is improved by the combined action of heat and other comprehensive driving forces.Moreover,in the process of in-situ combustion,a series of thermal modification reactions can further reduce the viscosity of crude oil and improve the quality of produced oil.However,in the actual production process,due to the lack of quantitative data of heavy oil upgrading reaction as a reference,it is impossible to determine the optimal reaction conditions and the degree of heavy oil upgrading,which leads to unreasonable fire drive scheme setting or improper use of auxiliary means such as catalysts and hydrogen donors to improve the efficiency of heavy oil burning reaction.Therefore,in this paper,aiming at the process of catalytic upgrading of hydrogen supply in the burning oil reservoir,Du84 heavy oil in Liaohe Oilfield is taken as the research object,and the scheme of adding Ni-Fe based super dispersed catalyst and tetrahydronaphthalene hydrogen donor as the upgrading technology to carry out the evaluation of experimental upgrading effect and mechanism research.Before the hydrogen supply catalytic experiment,the ignition temperature,preheating temperature of combustion tube and gas injection speed are selected as the controllable parameters of the conventional combustion tube experiment,so that the combustion reaction can achieve the best reaction efficiency without the participation of catalyst hydrogen donor.Then on the basis of these conditions,from the perspective of fuel consumption,combustion front propulsion distance,propulsion speed,combustion front maximum temperature,air consumption and oxygen utilization rate and other key experimental parameters,the experiment is carried out to select the optimal catalyst and the optimal hydrogen donor dosage separately,and the improvement capacity of catalyst and hydrogen donor is verified at the same time.Finally,1%wt catalyst and 0.7wt%hydrogen donor were selected for the experiment of catalytic hydrogen supply and upgrading.By comparing the experimental results with the experimental data of hydrogen supply without catalyst,the catalytic effect of hydrogen supply by burning heavy oil is quantitatively analyzed:after adding catalyst hydrogen supply,the combustion time of oil sample is shortened,and the maximum temperature of combustion front is obviously increased,in which the combustion time is 15%shorter than that of pure fire drive,and the maximum temperature of combustion front is 629?.At the same time,the catalyst also accelerates the advance speed of combustion front and makes the whole combustion process more stable.In terms of oil recovery,the oil recovery after hydrogen supply catalysis is 94.1%,which is 8.7%higher than that of no catalysis fire flooding experiment.Finally,through the viscosity,density,total hydrocarbon chromatogram and infrared spectrum analysis of the modified oil,the catalytic effect of hydrogen supply and upgrading in heavy oil combustion was quantitatively analyzed:the main peak carbon of the crude oil in the field changed from C₃₃to C₂₃,and the original high content heavy components had been consumed as fuel during the combustion process,and the hydrocarbon distribution mainly concentrated in C₂₀-C₃₅ also changed to C₁₆-C₂₀.The viscosity of oil produced by catalytic fire flooding is 1.07Pa·s?50??,the viscosity reduction rate is 98.86%,which is 10.72%higher than that of pure fire flooding.