Journal of Canadian Petroleum Technology
Volume 50, Number 9, September/October 2011, pp. 71-81

Summary

A new experimental technique of vanishing interfacial tension (VIT) has been reported in recent literature for quick and cost-effective determination of gas/oil miscibility. However, this technique has been criticized because of the perceived absence of compositional-path specification and lack of confirmation against standard gas/oil systems. In this paper, we address these concerns by conducting interfacial-tension (IFT) measurements at elevated pressures and temperatures in two standard gas/oil systems and at varying molar compositions of gas and oil in feed mixtures.

Though gas/oil ratio was found to have an impact on mass-transfer rates, the IFT between gas and oil was unaffected in the two standard gas/oil systems as the fluid phases approached equilibrium. This indicates compositional-path independence of gas/oil IFTs measured at near-equilibrium conditions; hence, miscibilities determined using the VIT technique. The minimum miscibility pressures (MMPs) determined using the VIT technique acceptably matched (within 5 to 8%) with the reported slim tube miscibilities for both the standard gas/oil systems. These experimental results clearly support wide use of the VIT technique for rapid and cost-effective determination of MMPs and minimum miscibility enrichments (MMEs) in improved-oil-recovery applications.

© 2011. Society of Petroleum Engineers

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History

• Original manuscript received: 5 September 2008
• Meeting paper published: 22 April 2006
• Revised manuscript received: 24 January 2011
• Manuscript approved: 28 January 2011
• Version of record: 13 September 2011