Title: Performance of immiscible and miscible CO₂ injection process in a tight carbonate reservoir (experimental and simulation approach)

Authors: Ali Abedini; Farshid Torabi; Nader Mosavat

Addresses: Faculty of Engineering and Applied Science, Petroleum Systems Engineering, University of Regina, Regina, SK S4S 0A2, Canada ' Faculty of Engineering and Applied Science, Petroleum Systems Engineering, University of Regina, Regina, SK S4S 0A2, Canada ' Faculty of Engineering and Applied Science, Petroleum Systems Engineering, University of Regina, Regina, SK S4S 0A2, Canada

Abstract: In this study, the technical feasibility of CO₂ injection in a core sample of a tight carbonate reservoir was investigated under various operating conditions. First, the minimum miscibility pressure (MMP) of CO₂/oil system was determined to be 1,907 Psia. The effects of the operating pressure as well as the injection flow rate of CO₂ on the oil recovery were examined. The results showed that at the operating pressures far below the MMP, the ultimate oil recovery factor is considerably low and increases as the pressure approaches near-miscible condition. When injection pressure was increased to 2,000 Psia, the ultimate oil recovery factor reached 0.81 and further increase in injection pressure did not significantly improve the recovery factor. For injection pressures lower than MMP (i.e., immiscible condition), increasing injection flow rate of CO₂ resulted in lower oil recovery, while at the pressures near and above the MMP, the ultimate oil recovery was much less dependent on CO₂ injection flow rate. All the test results were simulated using the CMG package, ver. 2011 and attempt was made to history match the experimental results. In this process, relative permeability curves were used as matching parameter. The simulation results were in good agreement with experimental values. [Received: March 12, 2013; Accepted: August 4, 2013]

Keywords: CO2 injection; carbon dioxide; immiscible gas injection; miscible gas injection; numerical simulation; tight carbonate reservoirs; minimum miscibility pressure; MMP; operating pressure; injection flow rate; oil recovery.

DOI: 10.1504/IJOGCT.2015.068994

International Journal of Oil, Gas and Coal Technology, 2015 Vol.9 No.3, pp.265 - 279

Received: 13 Mar 2013
Accepted: 04 Aug 2013
Published online: 24 Apr 2015 *

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