Experimental Comparative Study of Miscibility Between CO2 and Crude and Synthetic Oils-Case Study: One of Iranian South Reservoir

Document Type : Research Paper

Authors

1 Department of Petroleum Engineering, School of Chemical & Petroleum Engineering, Shiraz University, Shiraz

2 EOR Research Center, Department of Petroleum Engineering, School of Chemical & Petroleum Engineering, Shiraz University, Shiraz

Abstract

One of the major problems in Enhanced Oil Recovery (EOR) processes is the precipitation and deposition of asphaltene. This may lead to formation damage or partial and utter obstruction of flow passages around the well, deposition of asphaltene on the surface of reservoir rock as well as wettability alteration from water- to oil-wetted, and deposition in processing units. The present study investigates the miscibility of synthetic oils with or without asphaltene and compares it with that of crude oil from one of the Iranian oil fields in the presence of CO2 gas using vanishing interfacial tension (VIT) technique. The experiments were conducted at a given temperature but for different pressures. The experimental results showed that normal paraffin, in the oil phase, served as instability agent for the precipitation of asphaltene. The higher content of n-paraffin resulted in more and faster precipitation of asphaltene at the gas/oil interface. Once this occurred then the slope of IFT curve between gas and oil increased resulting in decreased CO2 solubility. Furthermore, based on IFT measurements, the speed of approaching to miscibility is reduced in vicinity of the onset of asphaltene precipitation. Thus, asphaltene aggregation in the gas/oil interface is accompanied by reduced slop of VIT curve which made the miscibility condition harder to reach.
 

Keywords

References

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Journal of Petroleum Research
Volume 25, 85-2 - Serial Number 85
January and February 2015
Pages 88-99

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