Gas injection is the most commonly used approach in enhanced oil recovery processes in the petroleum industry. Natural gas, nitrogen, and carbon dioxide are the most popular candidates for gas injection. However, gas cap (G.C.) could be another candidate somewhere, which is beneficial and cost-efficient. Therefore, it is essential to investigate and evaluate this kind of gas in the reservoir. Nevertheless, one of the most important key parameters that play an effective role in gas injection economy is the minimum miscibility pressure (MMP). MMP could be calculated with experimental investigations, empirical correlations, and computational methods like slim tube test and vanishing interfacial tension (VIT) or by means of reservoir simulation software such as ECLIPSE. This research is aiming at finding out the MMP of the oil/G.C. system and its mechanism; therefore, it has been attempted to appraise the MMP of the live/dead oil–G.C. system along with its mechanism at a constant reservoir temperature by the VIT technique. The results showed that the extracted MMP for the live oil–G.C. system is more than that for dead oil–G.C., and this value depends upon temperature, pressure, and composition of the system.

中文翻译：

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消失界面张力法的最小混相压力：将气顶注入死油/活油中的压力和成分的影响

注气是石油工业提高采收率过程中最常用的方法。天然气、氮气和二氧化碳是最流行的气体注入候选者。然而，gas cap (GC) 可能是另一个候选者，这是有益且具有成本效益的。因此，对储层中的此类气体进行调查和评价是十分必要的。然而，在注气经济性中发挥有效作用的最重要的关键参数之一是最小混相压力 (MMP)。MMP 可以通过实验研究、经验相关性和细管试验和消失界面张力 (VIT) 等计算方法或通过 ECLIPSE 等油藏模拟软件来计算。本研究旨在找出油/GC的MMP 制度及其机制；因此，试图通过 VIT 技术在恒定油藏温度下评价活/死油-GC 系统的 MMP 及其机理。结果表明，活油-GC 系统提取的MMP 比死油-GC 多，该值取决于系统的温度、压力和组成。