CO2与混合烷烃最小混相压力的界面张力法实验研究

Experiments on the minimum mixing pressure of CO2 and mixed alkane by using the interfacial tension regression method

关键词:  CO₂混相  混合烷烃  界面张力  最小混相压力  外推法

Key words:  CO₂ miscible phase  mixed alkane  interfacial tension  minimum mixing pressure (MMP)  extrapolation

摘要:

实验模拟伊朗西南部的阿瓦兹-班吉斯坦油田原油组分中的烷烃成分,不考虑沥青质,结合传统测界面张力的高压悬滴法和先进的计算机图像处理软件,分别测量了40 ℃和60 ℃下、压力范围分别为3.0～8.5 MPa和3.0～9.5 MPa时混合烷烃和被NaCl溶液饱和后的CO₂之间的界面张力,用外推法得到了对应的最小混相压力,成功验证了该方法的可行性,并对比文献讨论了实验结果。主要从原油组成成分和系统温度分析影响界面张力随压力的变化趋势,结果表明,低碳正构烷烃可以加快界面张力随压力下降的速度,高温下影响界面张力的综合因素造成压力关键点的形成。

Abstract:

Alkanes in Awaz-Banguistan crude oil from an oil field in southwestern Iran were simulated without considering asphaltene. At 40 ℃ and 60 ℃, and pressure ranges of 3.0-8.5 MPa and 3.0-9.5 MPa, the interfacial tensions between mixed alkane and CO₂ saturated by NaCl solution were measured by combining the traditional high-pressure pendant drop method and advanced computer image processing software. The corresponding minimum mixing pressure(MMP) was obtained by extrapolation. The feasibility of the method was successfully verified and the experimental results were discussed by comparing with literatures. The analysis are mainly carried out from two factors that affect the change trend of interfacial tension with pressure, i.e. crude oil composition and temperature. It is concluded that low carbon n-alkanes can accelerate the decrease of interfacial tension with pressure, and the formation of pressure key points is caused by comprehensive factors affecting interfacial tension at high temperature.