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The effect of designing parameter of WAG injection on enhancement of CO 2 trapping in heterogeneous formations: A numerical study
Author(s) -
Joodaki Saba,
Yang Zhibing,
Niemi Auli
Publication year - 2017
Publication title -
greenhouse gases: science and technology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.45
H-Index - 32
ISSN - 2152-3878
DOI - 10.1002/ghg.1719
Subject(s) - dissolution , trapping , water injection (oil production) , aquifer , residual , chemistry , hysteresis , petroleum engineering , groundwater , geology , mathematics , geotechnical engineering , ecology , algorithm , biology , physics , quantum mechanics
Dissolution and residual trapping of CO 2 injected in saline aquifers can be influenced by injection strategies applied. In this study, we focus on the water‐alternating‐gas (WAG) strategy and investigate the importance of parameters needed to design an effective WAG injection sequence, including (i) CO 2 and water injection rates, (ii) WAG ratio, and (iii) number of cycles. Using TOUGH2‐ECO2N, we perform 3D numerical simulations of sequences of CO 2 and water injection into a heterogeneous formation. Hysteresis in relative permeability and capillary pressure functions is considered based on the Land trapping model. Results show that to design a WAG injection in a high permeable formation, the WAG ratio and number of injection cycles are more important parameters than the CO 2 and water injection rates. Increasing the total amount of water injection (i.e., decreasing the WAG ratio for given total amount of injected CO 2 ) improves the CO 2 dissolution and residual trapping. It is also shown that increasing the number of injection cycles has a negative effect on both residual and dissolution trapping as measured at the end of the injection sequence, because both the free‐phase and the dissolved CO 2 plumes in the one‐cycle injection scenario reach farther distances and occupy larger reservoir volumes than in the multi‐cycle injection. This result means that while water injection following the CO 2 injection improves trapping in comparison with the CO 2 ‐only injection strategy, the WAG scheme with multiple cycles should not be chosen to enhance trapping for the scenario considered in this study. © 2017 Society of Chemical Industry and John Wiley & Sons, Ltd.