OPEN ACCESS
Deep geologic injection of supercritical carbon dioxide (CO2) for enhanced oil recovery (EOR) has been widely used for improved oil recovery from depleted oilfields since early 1970s. The CO2 injection maintains the pressure, mobilize the oil and release the petroleum resources that would otherwise be inaccessible. In addition to improving the oil recovery, the CO2-EOR contributes to minimize the impact of CO2-emissions to the atmosphere. The injected CO2 will be remained trapped in the under- ground geological formations, as the CO2 replace the oil and water in the pores. Carbonate reservoirs are characterized by low permeability and high heterogeneity, resulting in early breakthrough of gas and water and hence low oil recovery. The presence of naturally fractures in carbonate reservoirs is a major problem for the oil industry using CO2-EOR, because significant amount of CO2 are recycled to the well, and thereby not distributes in the reservoir. This study focuses on CO2 injection into a naturally fractured carbonate reservoir, including near-well simulations of CO2-distribution in the rock matrix. The simulations are carried out using the reservoir simulation software Rocx in combination with OLGA. The simulations show that CO2-injection into a naturally fractured carbonate reservoir in combination with closing of the fractured zones result in good distribution of CO2 in the reservoir.
CO2-EOR, fractured carbonate reservoir, inflow control, near-well simulations
[1] Hill, B., Hovorka, S. & Melzer, S., Geologic carbon storage through enhanced oil recovery. Energy Procedia, Elsevier Ltd: USA, 37, pp. 6808–6830, 2013.
[2] Khudaida, K.J. & Das, D.B., A numerical study of capillary pressure-saturation relationship for supercritical carbon dioxide (CO2) injection in deep saline aquifer. Chemi- cal Engineering research and Design, 92(12), pp. 3017–3030, 2012 http://dx.doi.org/10.1016/j.cherd.2014.04.020.
[3] Ettehadtavakkol, A., Lake, L.W. & Bryant, S.L., CO2-EOR and storage design optimi- zation. International Journal of Greenhouse Gas Control, 25, pp. 79–92, 2014. http://dx.doi.org/10.1016/j.ijggc.2014.04.006
[4] Fitch, P.J.R., Heterogeneity in the petrophysical properties of carbonate reservoirs. Doctor of Philosophy, The University of Leicester, Department of Geology, 2010.
[5] Moore, C.H., Carbonate Diagenesis and Porosity, Elsevier Science Publishers B.V: USA, 46, 1989.
[6] Tarek, T.A., Petrophysical characterization of the effect of Xanthan gum on drainage relative permeability characteristics using synthetic unconsolidated core plugs. Degree of Master of Petroleum Engineering, Dalhousie University, Halifax: Faculty of Engi- neering, 2014.
[7] Brettvik, M., Experimental and computational study of CO2 for EOR and secure storage reservoirs. Master Thesis, Telemark University College, Faculty of Technology, 2013.
[8] Pasala, S.M., CO2 displacement mechanisms: Phase equilibria effects and Carbon dioxide sequestration studies. Doctor of Philosophy, The University of Utah: Depart- ment of Chemical Engineering, 2010.
[9] NRG Energy. CO2 Enhanced Oil Recovery. NRG Fact Sheet, Texas: NRG Energy Inc. 2014, available at: http://www.nrg.com/documents/business/pla-2014-eor.pdf.
[10] Ghoodjani, E. & Bolouri, S.H., Experimental study and calculation of CO2-oil rela- tive permeability. Petroleum & Coal, Iran: Sharif University of Technology and Shahid Bahonar University, 53(2), pp. 123–131, 2011.
[11] NETL/DOE, Carbon dioxide enhanced oil recovery - untapped domestic energy supply and long term carbon storage solution. The Energy Lab, 2010.
[12] Haugen, Å., Fluid flow in fractured carbonates: wettability effects and enhanced oil recovery. PhD-dissertation, Department of Physics and Technology, University of Bergen, Norway, 2010.
[13] Aakre, H., Halvorsen, B., Werswick, B. & Mathiesen, V., Autonomous inflow control valve for heavy and extra-heavy oil. In SPE 171141, SPE Heavy and Extra Heavy Oil Conference - Latin America held in Medellin, Colombia, pp. 24–26, 2014.
[14] Aakre, H., Halvorsen, B., Werswick, B. & Mathiesen, V., Smart well with autonomous inflow control valve technology. SPE 164348-MS, SPE Middel East Oil and Gas Show and Exhibition held in Manama, Bahrain, 2013. http://dx.doi.org/10.2118/171141-ms
[15] Schlumberger, Fundamentals of wettability. Oilfield Review, 19(2), pp. 66–71, 2007.