Research Of Enhance Heavy Oil Recovery By Air Injection Assisted Cyclic Steam Stimulation

Technique of air injection assisted cyclic steam stimulation in heavy oil reservoir isinjection of air into the reservoir by cyclic steam stimulation. In this environment of hightemperature and pressure, O2in air reacts with heavy oil and is consumed, we use themechanisms of pressurizing cleanup, profile control, assisted gravity drainage, improving theheat efficiency of flue gas such as unreacted N2and generated CO2. Profile control effect andsand fixing effect of low temperature oxidation in heavy oil, to improve the effect of cyclicsteam stimulation. Among them, supplement the formation energy, and enhance the formationpressure are the key factors to improve the effect of cyclic steam stimulation. In order toevaluate the potential of exploitation with air injection assisted in heavy oil reservoir. In thispaper, we conducted a laboratory physical simulation experiment and reservoir numericalsimulation study of Du84heavy oil block of in Liaohe oilfield, clear the mechanism of airinjection assisted steam stimulation, providing theoretical basis and technical supportforheavy oil thermal recovery.（1）Carrying out the static experiment of high temperature and high pressure reactionkettle, on the basis of further comparison and synthetic investigation, the thesis comes to aconclusion: under the condition of reservoir exploited by air injection assisted cyclic steamstimulation, heavy oil takes place low temperature oxidation reaction with air, and has thecharacteristics of reducing glial content and increasing asphaltene content. Low temperatureoxidation reaction of heavy oil in Du84consist of oxygen reaction and pyrolysis reactions.The main solution of the reaction product is nonpolar compounds such as ketone, aldehyde,ester and so on. The gaseous products of the reaction is mainly comprised of residual O2, CO2,CO, and a small amount of hydrocarbon generation, SO2and H2S, the residual O2concentration is below4%, within a safe range.（2）Experiments of corrosion simulation in reaction kettle under high temperature andhigh pressure and sand filling model of tube show that: under the condition of reservoirpressure, viscosity of heavy oil increased after air injection; Changes in content of saturatedhydrocarbon oil is not great. Glial content decreased, while the asphaltene content increased,the heavy component content increased; permeability of the sandpack model decreased afterair oxidation at low temperature, the residual oil volume increased slightly, but little change.When the steam and air temperature is200℃, corrosive effect on N80steel is smaller. Theinhibitor or deoxidization agent can effectively reduce the corrosionrate of N80steel.（3）The stimulation mechanism of steam huff and puff assisted of injecting air is asfollows: effect of heating and visbreaking, reducing viscosity with solubility of gas, gravitydisplacement, gas booster, improving thermal efficiency with gas and the function of in-situsand curing.（4）Physical simulation experiments of sand pipe and large sand packed model and reservoir numerical simulation show that: In the process of steam stimulation, the injected airhas obvious pressurization, the plugging effect and significant effect of increasing yield,pressurization and effect of increasing yield are equivalent to N2assisted steam stimulation’s.Periodic oil production can be improved remarkably. The more times of stimulation is, themore obvious increase production effect is.