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Over the past 250 years, atmospheric CO₂ levels have increased markedly, rising from 270 to 370 parts per million (ppm), with half of this growth occurring within the last five decades. This trend is predominantly attributed to the intensified use of fossil fuels for energy production [1, 2]. Projections by the Organization for Economic Co-operation and Development (OECD) suggest that, without implementing effective mitigation measures, CO₂ emissions could rise by 70% by 2050. Such an increase is likely to drive global temperature rises of 3ºC to 6ºC by the end of this century [3]. This underscores the urgent need for strategies to control CO₂ emissions and limit the adverse environmental impacts of global warming.
Two primary approaches have been identified to address this challenge: transitioning from fossil fuels to renewable energy sources and adopting carbon capture and storage (CCS) technologies. Among these, CCS stands out as one of the most effective tools for reducing CO₂ emissions in the short-to-medium term [4]. Estimates suggest that CCS could contribute nearly 20% to global emission reductions by 2050, while its exclusion might lead to a 70% increase in the global costs of meeting emission reduction targets [5].
Geological carbon storage (GCS) in saline aquifers has emerged as a promising long-term strategy for CO₂ sequestration. In this context, this study explores the feasibility of CO₂ injection and storage by capillary trapping in carbonate rocks through a core flooding experiment under high-pressure (8,000 PSIG) and high-temperature (91ºC) conditions, simulating saline aquifer environments.
The experimental procedure involved saturating a low-permeability carbonate plug (Indiana Limestone) with NaCl brine at a concentration of 186 g/L. Subsequently, CO₂ gas was injected to displace the brine, maximizing gas storage. Finally, water was reinjected to displace the trapped gas and quantify the fraction of immobile gas.
The results confirmed the feasibility of saline aquifers as secure, long-term CO₂ storage sites. At 8,000 PSIG and 91ºC, approximately 18% of the pore volume was occupied by immobilized CO₂ following water injection (Figure 1). This residual trapping demonstrates the rock's capacity to retain CO₂ securely, enhancing the stability of geological storage systems. The trapped CO₂ saturation was evaluated at different temperature values. These findings underscore the vital role of saline aquifers in advancing CCS initiatives and meeting global carbon reduction objectives.
| References | [1] AR Kovscek and MD Cakici. Geologic storage of carbon dioxide and enhanced oil recovery. ii. cooptimization of storage and recovery. Energy conversion and Management, 46(11-12):1941–1956, 2005. [2] Ramin Moghadasi. Residual and critical saturation in geological storage of CO2: results from field studies, pore-network modelling and laboratory experiments. PhD thesis, Acta Universitatis Upsaliensis, 2022. [3] István Pomázi. Oecd environmental outlook to 2050: The consequences of inaction. Hungarian Geographical Bulletin, 61(4):343–345, 2012. [4] Yankun Sun, Qi Li, Duoxing Yang, and Xuehao Liu. Laboratory core flooding experimental systems for CO2 geosequestration: An updated review over the past decade. Journal of Rock Mechanics and Geotechnical Engineering, 8(1):113–126, 2016. [5] DECC CCS Roadmap. Supporting deployment of carbon capture and storage in the uk. London, UK: Department of Energy and Climate Change, 2012. |
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| Country | Brazil |
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