Title: Improving water-alternating-CO₂ flooding of heterogeneous, low permeability oil reservoirs using ensemble optimisation algorithm

Authors: Changlin Liao; Xinwei Liao; Longxin Mu; Xianghong Wu; Jing Chen; Hongna Ding; Feng Xu

Addresses: Petro China Research Institute of Petroleum Exploration and Development, Mail Box 910, Beijing 100083, China ' Petroleum Engineering Department, China University of Petroleum, Beijing, China ' Petro China Research Institute of Petroleum Exploration and Development, Mail Box 910, Beijing 100083, China ' Petro China Research Institute of Petroleum Exploration and Development, Mail Box 910, Beijing 100083, China ' United Energy Group Limited, Beijing, China ' Petroleum Engineering Department, China University of Petroleum, Beijing, China ' Petro China Research Institute of Petroleum Exploration and Development, Mail Box 910, Beijing 100083, China

Abstract: Injecting CO₂ into reservoir has been proven to be not only a feasible method for improving ultimate oil recovery, but also reducing CO₂ emissions and greenhouse effects. In this paper, the advantages of optimisation algorithm and numerical simulation are combined to establish mathematics model of production optimisation of water-alternate-gas (WAG) flooding. Augmented Lagrange function (ALF) and logarithm transformation (LT) are applied to convert constrained problems into unconstrained ones. The ensemble optimisation algorithm (EOA) is used to solve the latter. Then, the optimisation technology of reservoir production is formed. The optimisation technology is applied in a low permeability oil reservoir to test its feasibility of improving oil production. The results indicate that the CO₂ swept efficiency, miscible region and recovery, can be effectively improved by the optimisation technology which increases the economic benefit of the reservoir.

Keywords: CO₂ injection; CO₂ storage; ensemble optimisation algorithm; EOA; water-alternate-gas; WAG; oil reservoir.

DOI: 10.1504/IJGW.2017.084509

International Journal of Global Warming, 2017 Vol.12 No.2, pp.242 - 260

Received: 12 Dec 2014
Accepted: 21 Aug 2015
Published online: 12 Jun 2017 *

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