长庆姬塬油田黄3区CO2驱对采出原油物性影响

Effect of CO2 flooding on physical properties of produced crude oil in Huang 3 block of Changqing Oilfield

为深入研究CO2驱提高原油采收率方法对原油物性的影响,加深了解CO2驱油机理,为CO2驱现场试验效果分析提供理论依据,针对在长庆姬塬油田黄3区进行的CO2驱提高原油采收率现场试验,采用柱色谱法、气相色谱—质谱联用法等方法对长庆姬塬油田黄3区CO2驱油前后采出原油的物性变化进行了详细研究,重点考察了原油族组分含量、不同碳链烷烃含量、凝点、黏温曲线的变化情况。试验结果表明:注入CO2后,原油烷烃组分先减小后增加,非烃和沥青质组分先增加后减小;原油烷烃组分中轻质烷烃(C8—C16)先减小后增加,重质烷烃(C17—C40)含量先增加后减小;原油凝点先升高后降低,原油黏度低温(35℃)略有升高,高温下无明显变化。上述结果符合CO2混相驱油机理,原油物性的变化是由CO2抽提机理和CO2萃取机理共同作用的结果。通过上述研究,为CO2驱油机理的认识提供了数据支撑,为进一步制定提高CO2驱油效率方案提供了一定依据。

In order to study the effect of CO2 flooding on the physical properties of crude oil, understand the mechanism of CO2 flooding, and provide theoretical basis for the analysis of field test results of CO2 flooding, the field test of CO2 flooding in Huang 3 block of Jiyuan oilfield in Changqing was carried out by column chromatography and gas chromatography-mass spectrometry. The physical properties of crude oil produced before and after CO2 flooding in Huang 3 block of Jiyuan oilfield, Changqing, were stud. ied in detail by means of column chromatography, gas chromatography and mass spectrometry method and other methods. The changes of crude oil group content, different carbon chain alkanes content, solidification point and viscosity-temperature curve were mainly investigated. The experimental results show that after CO2 injection, the alkane fraction of crude oil first decreases and then increases, while the non-hydrocarbon and asphaltene fraction first increases and then decreases;the light alkane(C8-C16)in the alkane fraction of crude oil first decreases and then increases, the heavy alkane(C17-C40)content first increases and then de. creases;the pour point of crude oil first increases and then decreases, and the viscosity of crude oil at low temperature(35 ℃)in. creased slightly, but there was no obvious change at high temperature. The above results accord with the mechanism of CO2 misci. ble flooding. The change of crude oil physical properties is the result of the interaction of CO2 extraction mechanism. Through the above research, it provides data support for understanding the mechanism of CO2 flooding, and provides a certain basis for further formulating plans to improve the efficiency of CO2 flooding.