轻质油藏注空气过程中原油低温氧化反应的O_2—CO_2转换率

Oxygen-carbon Dioxide Conversion Ratio in Air-light Oil Low Temperature Oxidation Process

根据注空气过程中原油低温氧化反应机理和实验结果,分析氧气消耗率和CO2转换率及其影响因素.根据不同条件下原油低温氧化实验和高温氧化实验,计算分析了不同反应条件下的CO2转换率.实验结果表明,原油的低温氧化活性和CO2转化率主要受原油种类、反应温度、气体压力和砂的影响.温度和压力越高,反应速率越快,氧气消耗越完全,CO2转换率越大;加入砂后,反应速率加快,氧气消耗量增多,CO2转换率增高.与高温氧化相比,低温氧化的CO2转换率低于65％,通常在20％-50％范围内.

Air injection into light oil reservoirs is an effective technique for improving oil recovery, and thistechnique mainly depends on a spontaneous low temperature oxidation （LTO） process which occurs at reservoirtemperature. During LTO process of air injection, oxygen in the injected air is consumed and carbon dioxide can beproduced in the reservoir, leading to flue gas flooding and generating a significant amount of heat. Products of theair-oil oxidation reaction mainly include oxidized hydrocarbons and carbon oxides. Oxygen consumption rate andCO2 conversion ratio are analyzed based on the mechanisms of the LTO reaction and experimental results. The COgconversion ratios at different reaction conditions were calculated and the corresponding influencing factors are ana-lyzed. Experimental results show that the LTO activity of crude oils and the CO conversion ratio is mainly affectedby oil composition, and reaction temperature. Higher temperatures and pressures and existence of reservoir sandscan promote faster reaction rate, more or complete oxygen consumption, as well as higher CO2 conversion ratio. TheCO2 conversion ratio can be used to determine which reaction （low temperature or high temperature reactions） isprevailed at reservoir conditions.