Comparative evaluation of immiscible, near miscible and miscible CO2 huff-n-puff to enhance oil recovery from a single matrix–fracture system (experimental and simulation studies)

► In this study we examined the applicability of CO2 based huff-and-puff to fractured reservoirs. ► We performed a numerical simulation to history match the experimental results obtained. ► Effects of key parameters on the performance of CO2 based huff-and-puff are examined. ► It was concluded that...

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Bibliographic Details
Published in:Fuel (Guildford) 2012-03, Vol.93, p.443-453
Main Authors: Torabi, F., Qazvini Firouz, A., Kavousi, A., Asghari, K.
Format: Article
Language:English
Subjects:
Accuracy
Applied sciences
Carbon dioxide
Computer simulation
Cyclic CO2 injection
Energy
Energy. Thermal use of fuels
Exact sciences and technology
Fractured porous media
Fuels
Immiscible and miscible displacement
Mathematical models
Numerical simulation
Oil recovery
Phase (cyclic)
Recovery
Visual
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Summary:► In this study we examined the applicability of CO2 based huff-and-puff to fractured reservoirs. ► We performed a numerical simulation to history match the experimental results obtained. ► Effects of key parameters on the performance of CO2 based huff-and-puff are examined. ► It was concluded that injecting CO2 at supercritical condition is the most viable option for EOR. In this paper, the performance and efficiency of improved oil recovery in fractured porous media utilizing the cyclic CO2 injection process (otherwise known as CO2 huff-n-puff) are examined for immiscible, near-miscible and miscible pressure conditions. The main approach involved the comparison of simulation results to experimental data obtained from a laboratory CO2 huff-n-puff model. Previous experimental studies performed showed promising results for CO2 huff-n-puff process in a fractured model saturated with light oil. In order to upscale the experimental results and perform further studies, fully compositional simulation software was utilized to simulate the cyclic CO2 injection experiments. Prior to this, the phase behavior of a mixture of CO2 and decane (nC10) was studied and minimum miscibility pressure (MMP) of CO2–nC10 was found to be 1058psi, which was in good agreement with experimental results obtained by rising bubble apparatus (RBA) and visual tests [9,10]. The results of six sets of huff-n-puff experiments performed under constant temperature of 35°C and a wide range of pressures from 250 to 1500psi were simulated. Simulation results were in good agreement with those obtained experimentally. Throughout these studies, it has been found that near-miscible CO2 huff-n-puff process can improve the recovery factor from the light oil saturated experimental model by a factor of two. It was also discovered that the injection of CO2 at pressures much higher than the MMP was not significantly beneficial to recovery factor and may require further economical analysis. Also, cyclic CO2 performance improved greatly when conditions transitioned from immiscible to near-miscible (i.e. operating and injection pressures were increased to 1000psi) as indicated by a sharp increase in oil production.
ISSN:0016-2361
1873-7153
DOI:10.1016/j.fuel.2011.08.037