Experimental Study On Oxygen-enriched Combustion And Catalytic Oxidation Of Oil Sand In In-situ Combustion

In-situ combustion is a heavy oil thermal production method,which makes oxidation,cracking,viscosity reduction of the heavy oil possible after burning part of the oil reservoir by injecting air or oxygen to the oil reservoir.It is now being attached great importance in an era of increasingly scarce oil resources.Some criteria and methods of prediction and filtering are needed to make sure whether In-situ combustion can be applied to develop heavy oil reservoir in order to ensure the feasibility of the project.The condition of oil reservoir determines whether these methods could be used to enhance oil recovery.The rock mineral composition has a great influence on the frontal movement of in-situ combustion.The metal salt contained in the rock has a catalytic oxidation effect on burning front and the effect is associated with the type,content and surface area of metal salt.The physical and chemical properties of crude oil have a great influence on the deposition and high temperature oxidation of heavy oil fuel in the process of in-situ combustion.This thesis aims to explore the influence of the pyrite and 3 kinds of metal salts on the burning front through physical simulation of in-situ combustion by the combustion tube.To further investigate catalytic,and the mechanism,analysis of group composition and analysis of electron probe have been conducted for the oil sand samples before and after combustion,thermogravimetric analysis has been conducted for the crude oil sample which has been added these metal salt or added nothing,combustion reaction kinetic model has been established at last,analyze the catalyzed oxidation action of metal salt on the level of reaction mechanism.The result of the physical simulation combustion showed that the low content of pyrite promoted the high temperature oxidation reaction of heavy oil and improved the burning front peak temperature,while,the high content of pyrite increased the deposit amount of fuel.Electron probe micro analysis results showed that the pyrite reacted in the process of combustion and generated Fe O,and at the same time,part of the sulfur elements entered into the heavy oil.Group composition analysis showed that the resin was converted into Saturates hydrocarbons,Aromatic hydrocarbons withthe high temperature oxidation of heavy oil.The addition of pyrite made more asphalt turned into carbon deposition,and thus improved the deposit amount of fuel.Tin salt,copper salt,zinc salt improved the burning front.Among them,tin salt improved the whole process of fire flooding,but the effect was not obvious.Experiments showed that its effect was obvious only content is between 0.3 %~0.6 %,and the front temperature peak had no positive correlation with the tin salt content;while,copper salt kept burning front stable,and from temperatures in different section could keep at a high temperature range.Besides,burning front was not sensitive to the copper salt with content of 0.33 %~1.0 %.Zinc salt could significantly increase the burning rate and frontal combustion temperature of the fire flooding,but the combustion was not stable,sometimes local severe oxidation will occur.zinc salt just strengthened the stage of high-temperature oxidation,as a result,the effect could be improved by the increase of the zinc salt content.TGA displayed out main role of addition of metal salt was reducing the active energy of part stage during the oxidation of crude oil,making temperature interval reaction needed lower.On the detail,while three kinds of metal salts reduced the apparent activation energy of the oxidation phase,the change of DTG curves and DSC curves was not translating along temperature axis,it showed reaction type of high temperature oxidation could be changed,and heat releasing also was affected.While tin,copper,and zinc salts,three species metal salts existing in crude oil affected the apparent activation energy of oxidation,it existed differences among catalyst effect of low-temperature oxidation,fuel decomposition,high temperature oxidation three stages,the drop of apparent activation energy of oxidation in each stage was inconsistency.These status kept consistent well with the result of combustion simulation experiment,showed that oxidation kinetics analysis is reliable,and the catalytic mechanism of different metal salt is different.