Minireview on CO 2 Storage in Deep Saline Aquifers: Methods, Opportunities, Challenges, and Perspectives

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Wettability plays a vital role in evaluating the structural integrity of caprock, typically shale, during the implementation of geological carbon storage (GCS). There have been limited investigations of the wettability of clay minerals, which is common in shale formations, especially concerning carbon dioxide (CO 2 ) injection into saline aquifers. Furthermore, the consequence of CO 2 dissolution in aquifer brine, resulting in acidic conditions, on the wettability of clay−CO 2 −brine systems has not been thoroughly investigated. This study utilizes molecular dynamic modeling to investigate the wettability of the illite−CO 2 −brine system under conditions corresponding to a typical deep saline aquifer. The wettability has been studied through the measurement of the water contact angle, adopting the microscopic wetting technique. In addition, the wettability has been further examined qualitatively by the analysis of relative concentration and radial distribution function. A comparative analysis was also carried out to assess the findings of this study in relation to applicable literature data. The results of this study suggested that illite's wettability shifts from hydrophilic to hydrophobic under induced acidic conditions, irrespective of the brine's salinity and the type of CO 2 injection (either supercritical or subcritical). The water contact angle increased considerably from 44°in nonacidic conditions at 5 MPa and 333 K to 80°in acidic conditions at 10 MPa and 333 K. Furthermore, the competitive microscopic distribution revealed that acidic conditions facilitate the adsorption of CO 2 onto illite. The results also showed that acidic conditions have a greater impact on the wettability alteration under supercritical conditions as opposed to subcritical conditions. In addition to the acidic conditions, the water wettability of the illite−CO 2 −brine system is significantly reduced by elevated pressure, increased brine salinity, and a higher level of organic content in the rock. This work is expected to contribute to a better understanding of the wettability characteristics of caprocks in various geo-storage scenarios.

Section: Introductionmentioning

confidence: 99%

Molecular Dynamics Perspective of Illite Wettability in Induced Acidic Conditions during Supercritical and Subcritical Carbon Dioxide Sequestration in Deep Saline Aquifers

Ali,

Negash,

Ridha

et al. 2024

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“…While saline aquifers are typical sites for CO 2 storage, − hydrocarbon reservoirs offer an economically feasible solution, especially when the CO 2 injection also targets enhanced oil recovery. ,− Experimental studies in water-wet sand packs at ambient conditions show that, for high initial gas saturations, the trapped gas volume after a water injection can be larger in three-phase gas–oil–brine distributions than in two-phase gas–brine distributions . Meanwhile, three-phase core-scale experiments indicate that the gas storage capacity of capillary trapping after a gas–water injection cycle increases with the initial amount of oil present in the core before gas invasion .…”

Section: Introductionmentioning

confidence: 99%

Ripening of Capillary-Trapped CO₂ Ganglia Surrounded by Oil and Water at the Pore Scale: Impact of Reservoir Pressure and Wettability

Singh,

Friis,

Jettestuen

et al. 2024

Mass transfer by Ostwald ripening can impact the life and volume of capillary-trapped CO 2 in the subsurface. CO 2 storage in depleted hydrocarbon reservoirs encounters various preferences for wetting of the porous rock, while different reservoir pressures impact the miscibility between CO 2 and oil. The ripening behavior of CO 2 ganglia under such conditions is hitherto unknown. Herein, we study the impact of reservoir pressure and wettability on the ripening of CO 2 ganglia in the presence of oil (decane) and water at the pore scale, using a previously developed model that calculates the mass transfer based on chemical potential differences and the stationary three-phase fluid configurations with a multiphase level-set method. Through a comprehensive set of pore-scale simulations on 2D and 3D pore geometries, we show that ripening under immiscible conditions is faster than under near-miscible conditions, despite the fact that the permeability coefficients for CO 2 in oil and water in the mass-transfer equation are higher for the near-miscible condition. The longer equilibration time with increased reservoir pressure occurs because lower CO 2 −liquid interfacial tensions and CO 2 −liquid contact angles closer to 90°lead to lower bubble capillary pressures, lower pressure differences between the bubbles, and lower gradients in bubble pressure with volume. Ripening is faster for strong wetting states where the CO 2 −liquid contact angles are far lower (or higher) than 90°. We find that reservoir pressure, wettability, and oil/water capillary pressure can alter the CO 2 mass-transfer direction and hence the distribution of CO 2 ganglia at thermodynamic equilibrium. Simulations on a residual three-phase configuration in sandstone show that ripening leads to the growth of larger CO 2 ganglia, dissolution of small bubbles, and redistribution of trapped oil ganglia.

“…Currently, Carbon Capture, Utilization and Storage (CCUS) technologies offer a promising pathway for reducing carbon dioxide emissions and combating climate change (Figure ). By capturing, utilizing and storing carbon dioxide emissions, CCUS technologies prevent their release into the atmosphere and minimizes their impact on climate change. , The International Energy Agency (IEA) describes 78 pathways to achieve net-zero emissions globally by 2050, which would require the world to capture and store 79 billion tons of carbon dioxide annually. , As an intermediate link in the CCUS technologies chain, the choice of transportation method plays a crucial role in the deployment of CCUS infrastructure. , Common transportation methods include tanker truck, tanker train, pipeline and tanker ship . Among those methods, pipeline transportation is the primary option for CCUS projects, as depicted in Table .…”

Section: Introductionmentioning

confidence: 99%

Comprehensive Review on Leakage Characteristics and Diffusion Laws of Carbon Dioxide Pipelines

Shang,

Chen,

Yang

et al. 2024

The leakage of carbon dioxide pipelines may result in significant incidents, such as fracture expansion, harm to humans and animals, and the loss of transported substances. Therefore, it is essential for us to accurately explain the processes of leakage and diffusion in carbon dioxide pipelines. Initially, this paper introduces the hazards of carbon dioxide leakage and the physical processes involved in such incidents. Subsequently, it systematically reviews recent research involving experiments and numerical simulations of carbon dioxide pipeline leakage at the entire process, including the in-pipe depressurization process, the near-field jetting process, and the far-field diffusion process. Moreover, it specifically discusses the differences in leakage processes between buried and overhead pipelines, highlighting the distinctive appearance resulting from leaks in buried pipelines. The Span-Wagner (SW) equation of state was found to accurately predict the thermodynamic behaviors of carbon dioxide during the entire process of pure carbon dioxide leakage and diffusion. Conversely, the GERG-2008 equation of state is better suited for carbon dioxide with impurities. Additionally, Homogenous Relaxation Model (HRM) and Delay Homogeneous Equilibrium Model (DHEM) have provided more precise predictions of carbon dioxide leakage and diffusion processes compared to the Homogeneous Equilibrium Model (HEM). The Computational Fluid Dynamics (CFD) model, in comparison to simplified models like Process Hazard Analysis Software Tool (PHAST), can better account for complex terrains, specific environmental conditions, and the impact of nearby structures or other obstacles on the carbon dioxide diffusion process. Its prediction aligns more closely with the actual results. However, research on buried carbon dioxide pipelines is still in its infancy, with only preliminary insights available at this time. Finally, this paper summarizes the research deficiencies on the leakage characteristics and diffusion laws of carbon dioxide pipelines, while providing a perspective on future research possibilities.