Қазақстанның мұнай-газ саласының хабаршысыҚазақстанның мұнай-газ саласының хабаршысы2707-42262957-806XKMG Engineering10878110.54859/kjogi108781Research ArticleThe role of Capillary Hysteresis in Enhancing CO₂ Trapping Efficiency and Storage StabilityKhoramianRezareza.khoramian@nu.edu.kzhttps://orcid.org/0009-0008-7775-3816PourafsharyPeyman<p>Professor</p>peyman.pourafshary@nu.edu.kzhttps://orcid.org/0000-0003-4600-6670RiaziMasoud<p>Associate Professor</p>masoud.riazi@nu.edu.kzhttps://orcid.org/0000-0002-6843-621XSchool of Mining and Geosciences, Nazarbayev University110420257190991609202428112024Copyright © 2025, Khoramian R., Pourafshary P., Riazi M.2025<p><strong>Background: </strong>The intensifying impact of climate change demands innovative approaches to reduce atmospheric CO₂ levels. Carbon Capture and Storage (CCS) offers a viable solution by sequestering CO₂ in geological reservoirs. However, understanding the role of capillary hysteresis in CO₂ trapping is critical for optimizing CCS performance.</p> <p><strong>Aim: </strong>This study aims to investigate the influence of capillary hysteresis on CO₂ trapping efficiency in saline aquifers using detailed simulation models and varying hysteresis values.</p> <p>Materials and methods: Advanced CMG simulation software was utilized to model CO₂ injection and migration in saline aquifers spanning depths of 1200–1300 meters. The model, initially saturated with brine, applied water-alternating-gas (WAG) injection at hysteresis values of 0.2, 0.3, 0.4, and 0.5 to evaluate their effect on CO₂ trapping efficiency.</p> <p><strong>Results:</strong> The simulations demonstrated a direct positive correlation between hysteresis values and CO₂ trapping efficiency. At a hysteresis value of 0.5, nearly 100% CO₂ trapping was achieved. This increased efficiency was attributed to stronger capillary forces immobilizing CO₂ more effectively and reducing mobility towards caprock, thereby minimizing leakage risks.</p> <p><strong>Conclusion: </strong>The study highlights the key role of capillary hysteresis in enhancing CO₂ sequestration. Higher hysteresis values improve long-term storage stability, emphasizing the need for optimized WAG injection strategies in CCS applications.</p>CO₂ storagecapillary hysteresissaline aquifersWAG injectionclimate change mitigationCO₂ сақтаукапиллярлық гистерезистұзды сулы горизонттаркезектесіп су мен газ айдауклиматтың өзгеруін азайтухранение CO₂капиллярный гистерезиссоленые водоносные горизонтыпоочередная закачка воды и газасмягчение последствий изменения климата1.Sarkodie S.A., Owusu P.A., Leirvik T. Global effect of urban sprawl, industrialization, trade, and economic development on carbon dioxide emissions // Environmental Research Letters. 2020. 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