Study On Aquathermolysis Of Heavy Oil Synergetic Catalyzed By Reservoir Minerals And Exogenous Catalysts

With the declining recoverable reserves of light and easily recoverable reservoirs,heavy oil,which is difficult to extract,has become an important type of oil.Studies have shown that the high-temperature water vapor injected into the formation during hot mining can not only reduce the viscosity of heavy oil through physical action,but also reduce the colloidal asphaltene content in heavy oil through hydrothermal cracking reaction,so as to realize the modification of heavy oil,and the exogenous addition of catalyst can promote the hydrothermal cracking reaction of heavy oil.However,the synergistic catalytic effect between exogenous catalysts and reservoir in-situ minerals has been poorly studied.Based on the simulation of mineral content in the reservoir,a series of synthetic catalysts were added to improve the thermal cracking efficiency of heavy oil and water,and the reaction mechanism was explored.Firstly,according to the national or industrial standards,the basic physical properties of the heavy oil samples used in the experiment are determined and analyzed,and the reaction conditions of heavy oil are screened.The results showed that the reaction conditions of oil sample(oil sample 1)in Henan oilfield were determined as follows:the reaction temperature was 180℃,the reaction time was 4 h,the reaction water added was 30%of the oil sample amount,the reservoir mineral dosage was 0.2%of the oil sample amount,isopropanol was selected as the experimental hydrogen supply agent,and the isopropyl dosage was 30%of the oil sample dosage.According to the actual application of the aquathermolysis catalyst,the more commonly used water-soluble catalyst(citrate acid transition metal salt,MC)and oil-soluble catalyst(oleic acid transition metal salt,MO)were selected for synthesis.After aquathermolysis,it was found that the catalyst had a certain effect on viscosity reduction of heavy oil.Among them,Fe(Ⅲ)C and Mn(Ⅱ)C in water-soluble catalysts had good viscosity reduction effect on oil sample 1,and the viscosity reduction rates were 51.5%and 50.4%respectively compared with blank at 40℃.In oil-soluble catalysts,Fe(Ⅲ)O and Zn(Ⅱ)O had good viscosity reduction effects on oil sample 1,and the viscosity reduction rates were 57.2%and 53.6%respectively compared with blanks at 40℃.After the analysis of experimental results,Mn(Ⅱ)C+K and Zn(Ⅱ)O+K had the best synergistic catalytic viscosity reduction effect,and the viscosity reduction rate could reach 61.0%and 61.7%,respectively,compared with the blank at 40℃,and after isopropanol catalysis,the viscosity reduction rate was further improved,reaching 91.1%and 91.2%,respectively.A series of characterizations such as freezing point,thermogravimetric analysis,DSC analysis,component analysis,gas chromatography,wax crystal morphology analysis,and GC-MS analysis of aqueous organic compounds were carried out on heavy oil after reaction by different reaction systems,and the results were consistent with the viscosity reduction results.Finally,the reaction mechanism was studied by using model compounds,and it was confirmed that the depolymerization between macromolecules,the breaking of heteroatom chains,hydrogenation,ring opening and other effects mainly occurred during the reaction,thereby weakening the van der Waals force and hydrogen bond of the recombination division,inhibiting the formation of grid structure in heavy oil,and effectively reducing the viscosity of heavy oil.