Title: Potential application of the CO2-assisted gravity drainage process in a mature oil field: insights from reservoir-scale EOR evaluation

Authors: Watheq J. Al-Mudhafar; Dandina N. Rao

Addresses: Basrah Oil Company, Basrah, Iraq ' Department of Petroleum Engineering, Louisiana State University, Baton Rouge, LA, USA

Abstract: The gas-assisted gravity drainage (GAGD) process was implemented through continuous and cyclic immiscible injection to enhance the recovery of bypassed oil in the upper sandstone reservoir in the South Rumaila oil field, located in Southern Iraq. A compositional simulation model was constructed for the carbon dioxide (CO2) flooding evaluation through the GAGD process implementations. After achieving history matching, 20 vertical CO2 injectors and 11 horizontal oil producers were placed in top reservoir and oil zone, respectively. The immiscible CO2-GAGD performance was evaluated for 10 years of future prediction. The continuous and cyclic immiscible GAGD cases resulted in reaching recovery factor of 14.5% and 21.3% given the remaining oil, respectively. However, the recovery factor given the remaining oil was 7.6% through primary production by the end of prediction period. Additionally, the obtained amount of oil in 10 years primary production can be produced in only one year by the continuous case and in 8 months by the cyclic case. Consequently, the optimal implementation of the GAGD process is by adopting the cyclic CO2 flooding that efficiently enhance the recovery of bypassed oil. [Received: December 30, 2017; Accepted: December 17, 2018]

Keywords: gas-assisted gravity drainage; GAGD; immiscible CO2 flooding; enhanced oil recovery; South Rumaila field; insights learned.

DOI: 10.1504/IJOGCT.2020.108852

International Journal of Oil, Gas and Coal Technology, 2020 Vol.25 No.1, pp.19 - 40

Received: 30 Dec 2017
Accepted: 17 Dec 2018

Published online: 24 Apr 2020 *

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