Title: Effect of heterogeneity variation on the oil recovery performance in CO₂-WAG process

Authors: Gongyeong Kim; Youngmin Kim; Wonmo Sung; Jeonghwan Lee

Addresses: Department of Energy and Resources Engineering, College of Engineering, Chonnam National University, Gwangju 61186, Korea ' Department of Energy and Resources Engineering, College of Engineering, Chonnam National University, Gwangju 61186, Korea ' Department of Natural Resources and Environmental Engineering, College of Engineering, Hanyang University, Seoul 04763, Korea ' Department of Energy and Resources Engineering, College of Engineering, Chonnam National University, Gwangju 61186, Korea

Abstract: The main objective of this study is to investigate the effect of the heterogeneity on the oil recovery with various WAG ratios using a probabilistic manner in a CO₂-WAG process. For the probabilistic scheme, 100 cases of different permeability distributions were generated for each heterogeneity index and used as parameters for different compositional simulations. In generating the fields, the correlation lengths and directions were considered for various permeability fields within the same heterogeneity index. Oil recovery factors according to the WAG ratio were obtained from 2D areal and vertical models. As a result, the heterogeneity has a significant effect on determining the WAG ratio and performance. Especially, it was revealed that the direction of permeability has an effect on the determination of the WAG ratio. The optimum WAG ratio differs depending on the permeability direction of the reservoir. When the direction of permeability is consistent with the extension line between the injector and the producer, the proportion of water should be increased to obtain favourable oil recovery performance. [Received: December 4, 2015; Accepted: March 1, 2016]

Keywords: CO₂-water alternating gas; CO₂-WAG; heterogeneous reservoirs; WAG ratio; probabilistic evaluation.

DOI: 10.1504/IJOGCT.2017.083859

International Journal of Oil, Gas and Coal Technology, 2017 Vol.15 No.1, pp.60 - 76

Received: 11 Dec 2015
Accepted: 01 Mar 2016
Published online: 25 Apr 2017 *

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