中原油田轻质油藏注空气低温氧化反应机理研究

The Mechanism of Low Temperature Oxidation by Air Injection Process in Zhongyuan Light Oil Reservoir

林伟民 邓瑞健 刘 勇 陈永浩 牛保伦

LIN Wei-Min DENG Rui-Jian LIU Yong CHEN Yong-Hao NIU Bao-Lun

空气泡沫驱油技术是提高采收率的有效方法之一。为研究空气与中原油田地层原油的低温氧化反应机理，开展了空气-地层原油体系相态特征分析、低温氧化反应动力学测定、低温氧化反应影响因素和低温氧化反应区间及途径的实验研究。结果表明：胡状原油单次脱气体积收缩率为10.1126%，在90℃下的饱和压力为6.36 MPa，温度从90℃增至150℃、压力为23.5 MPa时，原油体积增加5.49%。油藏条件(90℃、23 MPa)下，胡状原油能溶解其自身体积9.07%的空气量，体积膨胀3.68%。原油与空气发生的低温氧化反应为一级反应，反应速率常数为5.1×10-3h-1，活化能为81.9 kJ/mol，指前因子为2.85×109 h-1，活化能较大，反应活性较低。原油具有较强的氧气消耗能力，在96 d内消耗自身体积2.4倍空气中的氧气，充分反应后，原油脱出溶解气中的氧气体积分数不超过3%。升高温度、压力、加入黏土及地层水均可促进氧化反应进行，其中温度是最主要因素。低温氧化反应后，饱和分和芳香分相对含量降低，而胶质和沥青质及氧元素相对含量升高。原油低温氧化反应分为加氧反应和断链反应两步。

Air foam flooding was one of the effective EOR methods. In order to research the mechanism of low temperature oxidation by air injection process, this study was carried into execution. Its main contents included air and formation oil phase behaviors, reaction kinetics of low-temperature oxidation, influencing factors of low temperature oxidation and the reaction path and reaction domain of low temperature oxidation. The results showed that the single degassing volume shrinkage of Huzhuang oil was 10.1126%, and the saturation pressure was 6.36 MPa at 90℃. The volume of oil increased 5.49% when the temperature increased from 90℃ to 150℃ and the pressure was 23.5 MPa. 9.07% air of its own volume could solve in oil and swelling factor was 3.68% at the formation condition (90℃、23 MPa). The reaction of low temperature oxidation between formation oil and air was first order reaction with 5.1×10-3 h-1 reaction rate constant, 81.9 kJ/mol activation energy, and 2.85×109 h-1 pre-exponential factor. The value of activation energy was high, but the activity was lower. Huzhuang oil was provided with the higher consume ability of oxygen. In 96 days, the oil consumed 2.4 times its own volume of oxygen in the air, and the oxygen volume fraction separated from oil was less than 3%. Increasing temperature or pressure, adding clay or formation water could enhance the reaction rate. Temperature was the main factor. Oil oxidation characters depended on its group composition. After the low-temperature oxidation reaction, the relative amounts of saturated and aromatic hydrocarbons reduced, and that of resin, asphaltene and oxygen increased. Formation oil oxidation reaction at low temperature could be divided into two steps, adding oxygen reaction and chain breaking reaction.