Optimization of miscible CO2 injection in the Nasiriyah oil field using a history-matched compositional reservoir model
DOI:
https://doi.org/10.31699/IJCPE.2026.3.8Keywords:
Proxy Model; Miscible CO2; Latin Hypercube Sampling; Optimization; CMOST; Enhanced oil recoveryAbstract
This study aims to evaluate and optimize the performance of miscible CO2 injection in the heterogeneous Mishrif carbonate reservoir, with the objective of enhancing oil recovery and improving reservoir production performance. A compositional reservoir model was developed using CMG-GEM to accurately represent fluid behavior and phase transitions. Fluid characterization and PVT data matching were performed using WinProp with the Soave–Redlich–Kwong (SRK) equation of state. History matching of production and pressure data was also carried out to validate the reliability of the reservoir model. A natural depletion scenario was adopted as a base case for comparison, after which miscible CO2 injection was implemented, and an optimization study was conducted using CMOST based on Latin Hypercube Sampling (LHS) and a proxy model to identify optimal operating conditions. The results of the natural depletion case showed a continuous decline in reservoir pressure, with a final recovery factor of only 2.74%. In contrast, CO2 injection improved reservoir performance and increased the recovery factor to 4.22% in the optimized case, with delayed gas breakthrough and a reduced gas-oil ratio compared to the base case. The study confirms that miscible CO2 injection is an effective enhanced oil recovery technique for the Mishrif reservoir, offering a significant increase in production while improving reservoir management and maintaining pressure support.
Received on 13/06/2026
Received in Revised Form on 30/07/2026
Accepted on 30/07/2026
Published on 30/09/2026
References
[1] M. Y. Khan, A. Kohata, H. Patel, F. I. Syed, and A. K. Al Sowaidi, “Water Alternating Gas WAG Optimization Using Tapered WAG Technique for a Giant Offshore Middle East Oil Field,” Abu Dhabi International Petroleum Exhibition & Conference, Society of Petroleum Engineers (SPE), Nov. 2016. https://doi.org/10.2118/183181-MS
[2] S. Mohammadi, M. Khalili, and M. Mehranfar, “The Optimal Conditions for the Immiscible Gas Injection Process: A Simulation Study,” Petroleum Science and Technology, vol. 32, no. 2, pp. 225–239, Jan. 2014. https://doi.org/10.1080/10916466.2011.557680
[3] S. Mohammadi, R. Kharrat, M. Khalili, and M. Mehranfar, “Optimal Conditions for Immiscible Recycle Gas Injection Process: A Simulation Study for One of the Iranian Oil Reservoirs,” Scientia Iranica, vol. 18, no. 6, pp. 1407–1414, 2011. https://doi.org/10.1016/j.scient.2011.10.003
[4] C. He, H. Liu, Z. Yang, J. Zhao, Y. Li, X. Wang, L. Zhang, and W. Pu, “Phase Behavior and Miscible Mechanism in the Displacement of Crude Oil with Associated Sour Gas,” Oil & Gas Science and Technology – Revue d’IFP Energies Nouvelles, vol. 74, Art. 54, Jun. 2019. https://doi.org/10.2516/ogst/2019024
[5] M. Samba, Y. Li, M. A. Naser, and M. O. Elsharafi, “Comparison of Different Gases Injection Techniques for Better Oil Productivity,” Journal of Petroleum and Geothermal Technology, vol. 2, no. 1, pp. 1–13, May 2021.
[6] A. Karkevandi-Talkhooncheh, S. Hajirezaie, A. Hemmati-Sarapardeh, M. M. Husein, K. Karan, and M. Sharifi, “Application of Adaptive Neuro-Fuzzy Inference System Optimized with Evolutionary Algorithms for Modeling CO₂–Crude Oil Minimum Miscibility Pressure,” Fuel, vol. 205, pp. 34–45, Oct. 2017. https://doi.org/10.1016/j.fuel.2017.05.026
[7] A. Barati-Harooni, A. Najafi-Marghmaleki, A. Tatar, A. H. Mohammadi, and M. Arabloo, “Estimation of Minimum Miscibility Pressure (MMP) in Enhanced Oil Recovery (EOR) Process by N₂ Flooding Using Different Computational Schemes,” Fuel, vol. 235, pp. 1455–1474, Jan. 2019. https://doi.org/10.1016/j.fuel.2018.08.066
[8] L. W. Lake, Primer on Enhanced Oil Recovery. Elsevier, 2019. https://doi.org/10.1016/C2017-0-03909-5
[9] K. Zhang, N. Jia, F. Zeng, and P. Luo, “A New Diminishing Interface Method for Determining the Minimum Miscibility Pressures of Light Oil–CO₂ Systems in Bulk Phase and Nanopores,” Energy & Fuels, vol. 31, no. 11, pp. 12021–12034, Nov. 2017. https://doi.org/10.1021/acs.energyfuels.7b02439
[10] K. Zhang, N. Jia, and F. Zeng, “Application of Predicted Bubble-Rising Velocities for Estimating the Minimum Miscibility Pressures of the Light Crude Oil–CO₂ Systems with the Rising Bubble Apparatus,” Fuel, vol. 220, pp. 412–419, May 2018. https://doi.org/10.1016/j.fuel.2018.01.100
[11] K. Zhang, N. Jia, S. Li, and L. Liu, “Quantification and Evaluation of Thermodynamic Miscibility in Nanoconfined Space,” Industrial & Engineering Chemistry Research, vol. 58, no. 11, pp. 4609–4624, Mar. 2019. https://doi.org/10.1021/acs.iecr.8b06297
[12] Y. Khalili, S. Abassi, and M. Bagheri, “A Comprehensive Review of Gas-Based Enhanced Oil Recovery (Gas-Based EOR) Techniques: Mechanisms, Applications, and Future Trends,” The Canadian Journal of Chemical Engineering, Feb. 2026. https://doi.org/10.1002/cjce.70238
[13] A. S. Zakaria, “Optimizing Simulation Studies for Miscible Gas Injection Process Using Horizontal Wells,” SPE Enhanced Oil Recovery Conference, Society of Petroleum Engineers (SPE), Jul. 2011. https://doi.org/10.2118/144069-MS
[14] N. M. Al Hinai and A. Saeedi, “Miscible Displacement Oil Recovery,” in Enhanced Oil Recovery – Selected Topics, IntechOpen, 2022. https://doi.org/10.5772/intechopen.105757
[15] G. F. Teletzke, P. D. Patel, and A. L. Chen, “Methodology for Miscible Gas Injection EOR Screening,” SPE International Improved Oil Recovery Conference in Asia Pacific, Society of Petroleum Engineers (SPE), Dec. 2005. https://doi.org/10.2118/97650-MS
[16] S. K. Masalmeh, S. A. Farzaneh, M. Sohrabi, and M. Alhammadi, “Experimental Investigation of Factors Affecting Oil Recovery and Displacement Efficiency of CO₂ Injection in Carbonate Reservoirs,” SPE Journal, vol. 30, no. 3, pp. 1492–1509, Mar. 2025. https://doi.org/10.2118/218525-PA
[17] M. K. Emera and H. K. Sarma, “Use of Genetic Algorithm to Predict Minimum Miscibility Pressure (MMP) between Flue Gases and Oil in Design of Flue Gas Injection Project,” SPE Middle East Oil and Gas Show and Conference, Society of Petroleum Engineers (SPE), Mar. 2005. https://doi.org/10.2118/93478-MS
[18] A. Hashemi Fath and A.-R. Pouranfard, “Evaluation of Miscible and Immiscible CO₂ Injection in One of the Iranian Oil Fields,” Egyptian Journal of Petroleum, vol. 23, no. 3, pp. 255–270, Sep. 2014. https://doi.org/10.1016/j.ejpe.2014.08.002
[19] Z. Li, Gas Injection Methods. Gulf Professional Publishing, an Imprint of Elsevier, 2023.
[20] S. Zendehboudi, M. A. Ahmadi, A. Bahadori, A. Shafiei, and T. Babadagli, “A Developed Smart Technique to Predict Minimum Miscible Pressure—EOR Implications,” The Canadian Journal of Chemical Engineering, vol. 91, no. 7, pp. 1325–1337, Jul. 2013. https://doi.org/10.1002/cjce.21802
[21] W. Yu, H. R. Lashgari, K. Wu, and K. Sepehrnoori, “CO₂ Injection for Enhanced Oil Recovery in Bakken Tight Oil Reservoirs,” Fuel, vol. 159, pp. 354–363, Nov. 2015. https://doi.org/10.1016/j.fuel.2015.06.092
[22] P. Luo, W. Luo, and S. Li, “Effectiveness of Miscible and Immiscible Gas Flooding in Recovering Tight Oil from Bakken Reservoirs in Saskatchewan, Canada,” Fuel, vol. 208, pp. 626–636, Nov. 2017. https://doi.org/10.1016/j.fuel.2017.07.044
[23] M. S. A. Perera, R. P. Gamage, T. D. Rathnaweera, A. S. Ranathunga, A. Koay, and X. Choi, “A Review of CO₂-Enhanced Oil Recovery with a Simulated Sensitivity Analysis,” Energies, vol. 9, no. 7, Art. 481, Jul. 2016. https://doi.org/10.3390/en9070481
[24] M. K. Emera and H. K. Sarma, “Prediction of CO₂ Solubility in Oil and the Effects on the Oil Physical Properties,” Energy Sources, Part A: Recovery, Utilization, and Environmental Effects, vol. 29, no. 13, pp. 1233–1242, Aug. 2007. https://doi.org/10.1080/00908310500434481
[25] H. A. Abdulameer and S. Hamd-Allah, “Reservoir Model and Production Strategy of Mishrif Reservoir–Nasiriyah Oil Field, Southern Iraq,” Journal of Petroleum Research and Studies, vol. 10, no. 3, pp. 54–85, Nov. 2020. https://doi.org/10.52716/jprs.v10i3.330
[26] R. M. Idan and A. L. Salih, “Reservoir Quality Related to Diagenetic Development in the Carbonate Mishrif Formation: A Case Study from the X Oilfield, Southern Iraq,” The Iraqi Geological Journal, pp. 100–114, Sep. 2023. https://doi.org/10.46717/igj.56.2C.8ms-2023-9-14
[27] F. M. Al-Najm, M. N. Shehab, H. A. Al-Samer, and M. H. Hafiz, “Studying the Statistical and Petrophysical Characteristics of the Mishrif Formation in the Nasiriyah Oil Field, Southern Iraq,” The Iraqi Geological Journal, pp. 101–114, Mar. 2024. https://doi.org/10.46717/igj.57.1C.8ms-2024-3-20
[28] G. Soave, “Equilibrium Constants from a Modified Redlich-Kwong Equation of State,” Chemical Engineering Science, vol. 27, no. 6, pp. 1197–1203, Jun. 1972. https://doi.org/10.1016/0009-2509(72)80096-4
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