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The key role of hydroxyl in thermal transport at the silica-water interface: A molecular dynamics simulation
Get PDFA comprehensive understanding of thermal transport across solid-liquid interfaces is crucial for enhancing the performance of micro- and nanoscale devices, especially at the silica-water interface, which plays a key role in many applications in energy conversion and medical technologies. The adsorbed water layer at the silica interface plays a core role in solid-liquid interface thermal transport. However, the molecular-level structural transitions of this layer and their correlation with thermal transport mechanisms have not been extensively studied. In this work, molecular dynamics simulations were used to study the thermal transport mechanisms at silica-water interfaces with different hydroxyl densities, focusing on how interfacial H-bonds and layered structures influence interfacial thermal transport characteristics. The results of the study show that the interfacial thermal conductance increases with the hydroxyl density, while the density distribution of water molecules at the silica interface shows an opposite trend. The formation of H-bonds at the interface is identified as the main cause of this anomalous behavior. Through density, charge, H-bonds, and water molecule orientation distribution, the bilayer structure of the adsorbed water layer at the silica interface was defined at the molecular level, which is composed of the binding interface layer and the diffuse layer. The binding interface layer plays a decisive role in interfacial thermal transport. Through the analysis of interfacial potential energy, H-bonds dynamics, and Vibrational density of states, the microscopic mechanisms of thermal transport at silica-water interfaces with different hydroxyl densities were proposed by this work. These findings may provide new insights into the understanding of thermal transport mechanisms at solid-liquid interfaces.Document Type: Original articleCited as: Ma, M., Li, J., Zhang, X., Qing, S. The key role of hydroxyl in thermal transport at the silica-water interface: A molecular dynamics simulation. Capillarity, 2025, 17(3): 81-96. https://doi.org/10.46690/capi.2025.12.0
Mitigating risks in deep sea gas hydrate production: A new perspective on interpreting thermo-hydro-mechanical feedbacks
Get PDFNatural gas hydrate deposits in marine sediments represent a vast potential energy resource, yet their commercial extraction remains a complex scientific and engineering challenge due to the intricate thermo-hydro-mechanical-chemical coupling processes triggered during production. This perspective paper synthesizes recent progress and outlines persistent hurdles in understanding the coupled mechanical-seepage-thermal response inherent to gas hydrate exploitation, while introducing a novel theoretical and methodological framework that integrates cross-scale constitutive modeling, multiscale permeability upscaling, and nonlinear flow characterization to better interpret key feedback mechanisms. Looking forward, overcoming these barriers requires interdisciplinary approaches leveraging advanced sensing technologies, machine learning-assisted modeling, and novel upscaling methodologies. Furthermore, internationally collaborative long-term field trials with comprehensive monitoring are essential to validate next-generation simulators and develop adaptive management strategies.Document Type: PerspectiveCited as: Gong, B., Lei, G., Chen, L., Zhao, Y. Mitigating risks in deep sea gas hydrate production: A new perspective on interpreting thermo-hydro-mechanical feedbacks. Advances in Geo-Energy Research, 2025, 17(3): 267-270. https://doi.org/10.46690/ager.2025.09.0
A multi-field coupling model for CO₂ enhanced shale gas recovery integrating chemical dissolution and mechanical weakening effects
Get PDFCO₂ enhanced shale gas recovery technology can effectively promote gas production and achieve CO₂ storage. The coupling relationship among the thermo-hydro-mechanical fields within the reservoir exhibits dynamic evolution during CO₂ injection. Additionally, the geochemical interactions between shale and CO₂ cause mineral dissolution and mechanical weakening, significantly influencing the shale reservoir characteristics. However, the impact mechanism of this coupling effect on CO₂ enhanced shale gas recovery is still unclear. This study first establishes and validates a thermo-hydro-mechanical-chemical coupling model. Then, the impacts of CO₂ injection on the reservoir physical characteristics and gas recovery under different influencing factors are investigated. The findings indicate that the relative permeability of the matrix and fractures in shale demonstrates an initial rapid increase, followed by a gradual decline during CO₂ injection. This complex behavior is governed by the comprehensive impacts of effective stress evolution, competitive adsorption, chemical dissolution, and mechanical weakening. During the initial injection period, gas production and CO₂ storage increase rapidly as CO₂ injection pressure increases and injection temperature decreases, primarily governed by the effective stress and disso lution effect. During the middle and late injection periods, competitive adsorption-induced swelling and mechanical weakening effects are dominant, rendering the process highly sensitive to reservoir stress. At this stage, excessive injection pressure and excessively low temperatures accelerate permeability reduction. Consequently, when evaluating the efficacy of CO₂ enhanced shale gas recovery, it is essential to incorporate the coupling relationship between the chemical dissolution-mechanical weakening effect and thermo hydro-mechanical fields of shale reservoir.Document Type: Original articleCited as: Yang, K., Sun, Y., Zhou, J., Chen, Q., Deng, G., Li, D. A multi-field coupling model for CO₂ enhanced shale gas recovery integrating chemical dissolution and mechanical weakening effects. Advances in Geo-Energy Research, 2025, 18(2): 180-194. https://doi.org/10.46690/ager.2025.11.0
Influence of thermodynamic and stress conditions in saline aquifers on CO₂ drainage: Optimization of CO₂ storage and energy recovery
Get PDFThe accumulation of immobile residual water during CO₂ injection for brine displacement significantly impairs storage efficiency, injectivity, and fluid migration-key factors for scaling up CO₂-based energy technologies. This study investigates the factors governing residual water saturation under different CO₂ phases and effective stress conditions in simulated subsurface environments. The results indicate that under constant effective stress, gaseous CO₂ yields the highest residual water saturation, followed by its supercritical and liquid states. As such, an inverse relationship is observed between residual water saturation and storage efficiency/capacity, underscoring the potential for jointly optimizing energy recovery and CO₂ sequestration. The analysis of the CO₂-brine-rock system confirms that capillary forces control residual water saturation. Increased interfacial tension or contact angle cosine value raises capillary entry pressure, hindering displacement and elevating irreducible water saturation. Moreover, higher effective confining pressure reduces capillary radius and creates “dead pores”, thereby increasing capillary pressure and enhancing water trapping in the core. The findings give critical insights into how CO₂ phase behavior and confining pressure govern residual water saturation, displacement efficiency and migration in the reservoir, directly informing strategies for optimal CO₂ storage reservoir selection and enhanced oil recovery operations.Document Type: Original articleCited as: Yan, M., Lu, Z., Yang, X., Zheng, J., Wang, L., Hong, Y. Influence of thermodynamic and stress conditions in saline aquifers on CO₂ drainage: Optimization of CO₂ storage and energy recovery. Advances in Geo-Energy Research, 2025, 18(3): 207-217. https://doi.org/10.46690/ager.2025.12.0
Characterization of water micro-distribution behavior in shale nanopores: A comparison between experiment and theoretical model
Get PDFDue to the existence of fracturing fluid and formation water in shale gas reservoirs, the coexistence of gas and water in nanopores is prevalent. The pore water in the reservoir, on the one hand, affects gas flow behavior and permeability. On the other hand, it blocks pore throats and occupies adsorption sites on the pore surface, consequently reducing the gas adsorption capacity. The occurrence of pore water in shale reservoirs holds significant importance for shale gas resources exploration and development. In this paper, the shale from the Longmaxi Formation, Sichuan Basin was selected as the research target. The content and micro-distribution behavior of pore water were evaluated through centrifugation-nuclear magnetic resonance experiment and theoretical model. The results demonstrated that the content of free water would be underestimated by the experiment, with 2.55%-6.80% lower than that calculated by theoretical model. Moreover, due to the limitations of nuclear magnetic resonance experiment, the adsorbed water in mesopores and macropores might be mistakenly identified as that in smaller pores. As a result, the theoretical model is more applicable for characterizing the micro-distribution behavior of pore water than the origin nuclear magnetic resonance data.Document Type: Short communicationCited as: Jiao, X., He, W., Tian, Z., Zhou, S., Wang, H., Xia, Y. Characterization of water micro-distribution behavior in shale nanopores: A comparison between experiment and theoretical model. Advances in Geo-Energy Research, 2025, 15(1): 79-86. https://doi.org/10.46690/ager.2025.01.08
Nanostructure and evolution of thin shells in brittle-ductile shear zones
Get PDFThe brittle-ductile deformation of rocks forms the foundation of structural geology, engineering geology and petroleum geology. Although brittle-ductile deformation structures and their evolutionary processes have been extensively investigated at macroscopic and microscopic scales, a reliable discrimination model remains elusive at the nanoscale. To establish distinctive nanostructural models for brittle-ductile deformations, this study combines the scanning electron microscopy analysis of thin shells within brittle-ductile shear zones with high-temperature and high-pressure experimental simulations. The brittle and ductile thin shell models exhibit markedly different structures. The models reveal a tripartite architecture in brittle thin shells: a vice-surface on top layer; a middle layer comprising individual spherical nanoparticles, nanoparticle aggregates and multi-aggregate nanoparticles; a basal substrate layer. In contrast, the ductile thin shell does not have a vice-surface on top layer or a basal substrate layer and its nanostructures are characterized by fibrous, chain-ball and schistose nanoparticles with their associated aggregate structures. Applying the space-for-time assumption, the evolution of thin shells in the shear zone was reconstructed, demonstrating that the brittle-ductile-viscous transition drives nanoparticle transformations through granularization - alienation - reuniting - reproduction sequences. This work extends the discrimination model of brittle-ductile deformation from the microscopic scale to the nanoscale.Document Type: Original articleCited as: Cai, Z., Liu, Y., Li, J., Sun, Y. Nanostructure and evolution of thin shells in brittle-ductile shear zones. Advances in Geo-Energy Research, 2025, 17(1): 56-67. https://doi.org/10.46690/ager.2025.07.0
Capillary-driven processing in carbon fiber-reinforced polymer composites: From multiscale modeling to advanced manufacturing
Get PDFThe action of capillary pressure plays a crucial role in the formation of voids during the molding process of fiber-reinforced polymer composites. It is primarily driven by surface and interfacial tension, resulting in macroscopic liquid flow controlled by pressure differences. However, due to the influence of microscopic-scale effects, modeling and characterizing the capillary effects in carbon fiber-reinforced polymer composites presents significant challenges. This review offers a comprehensive summary of the relevant theories on capillary pressure, including fundamental theory, average capillary pressure theory, and interface enhancement theory. Furthermore, it discusses methods related to contact angle experiments, capillary pressure experiments, and multiscale numerical simulations while illustrating examples of capillary forces in carbon fiber-reinforced polymer composites. This paper aims to help readers gain a deeper understanding of the mechanisms and applications of the capillary effect in carbon fiber-reinforced polymer composites.Document Type: Invited reviewCited as: Li, Z., Sun, Y., Chen, Y., Liu, Z., Tang, Y., Yang, W. Capillary-driven processing in carbon fiber-reinforced polymer composites: From multiscale modeling to advanced manufacturing. Capillarity, 2025, 16(3): 77-86. https://doi.org/10.46690/capi.2025.09.0
Thermal-hydraulic-mechanical-chemical multiphysics coupling for geothermal energy development
Get PDFAs asustainable and renewable energy source, geothermal energy holds significant potential for addressing global energy demands and mitigating climate change. However, the development of geothermal resources involves complex interactions among temperature, f luid flow, stress, and chemistry, collectively known as thermal-hydraulic-mechanical chemical multiphysics coupling. This work aims to provide a comprehensive overview of such a coupling simulation in geothermal energy development, encompassing theoretical frameworks, numerical models, and practical applications. By integrating insights from various disciplines, this perspective contributes to advancing the understanding and optimization of geothermal energy extraction processes.Document Type: PerspectiveCited as: Sun, Z., Huang, H., Jiao, K., Wang, D., Zhang, T. Thermal-hydraulic-mechanical-chemical multiphysics coupling for geothermal energy development. Advances in Geo-Energy Research, 2025, 16(2): 91-94. https://doi.org/10.46690/ager.2025.05.01
Investigation of effect and mechanism of active water and CO2 huff-and-puff on enhanced oil recovery in tight reservoirs
Get PDFHuff-and-puff is a key technology for the efficient recovery of oil and gas from tight reservoirs. Active water and CO2 are two huff-and-puff media with great development potential; however, their effects on enhanced oil recovery and the contribution of imbibition displacement to enhanced oil recovery need further investigation. In this paper, short cores were spliced into long cores for huff-and-puff experiments, and then nuclear magnetic resonance testing was performed to test the transverse relaxation time spectrum of different core sections at different huff-and-puff cycles. Subsequently, the enhanced oil recovery effects, limited effective distances, and influencing factors of active water and CO2 huff and-puff were evaluated. Meanwhile, a comparative experiment without well soaking in some specific huff-and-puff cycles was designed to quantitatively split the contribution rate of elastic displacement and imbibition displacement. The results show that active water huff-and-puff mainly mobilizes crude oil in large pores, while CO2 huff-and-puff can also mobilize crude oil in small pores. The cumulative oil recovery of active water and CO2 after 4 cycles of huff-and-puff was 24.78% and 40.89%, respectively, and the limited effective distances were 6-8 cm and 8-10 cm, respectively. Elastic displacement is considered the main enhanced oil recovery mechanism of active water and CO2 huff and-puff, while imbibition displacement accounts for 20.86% and 31.52%, respectively. Due to its good diffusion and mass transfer ability, CO2 can more fully participate in the mechanism of imbibition displacement and further improve oil recovery. The findings of this paper can provide valuable theoretical and field data support for the application of huff-and-puff technology in tight reservoirs.Document Type: Original articleCited as: Chen, X., Zhu, J., Chao, L., Trivedi, J., Liu, J., Liu, S. Investigation of effect and mechanism of active water and CO2 huff-and-puff on enhanced oil recovery in tight reservoirs. Capillarity, 2025, 14(1): 23-34. https://doi.org/10.46690/capi.2025.01.0
Permeability prediction in hydrate-bearing sediments via pore network modeling
Get PDFNatural gas hydrates in marine sediments undergo phase transitions under non-equilibrium conditions, making it challenging to accurately measure the permeability characteristics of hydrate-bearing sediments using experimental methods. In this study, pore network modeling is utilized to simulate the hydrate formation process and investigate the singlephase and two-phase permeability of hydrate-bearing sediments, and a comparative analysis was performed on consolidated and unconsolidated sediment samples. The results revealed the evolution of effective permeability as a function of hydrate saturation, and quantitative relationships were observed for the water retention curves and gas-water relative permeability, emphasizing the influence of pore structure and hydrate distribution on flow behavior. On the basis of the simulation results, predictive methods for irreducible water saturation, maximum water saturation, and key parameters in the van Genuchten and Brooks-Corey models for hydrate-bearing sediments are proposed. The findings provide deeper insights into gas-water flow dynamics in hydrate-bearing sediments and offer valuable guidance for hydrate resource exploitation, the assessment of environmental risks associated with hydrate dissociation, and the evaluation of carbon sequestration potential.Document Type: Original articleCited as: Zhang, Y., Liu, L., Luo, L., Ma, J., Ji, Y., Xiao, T., Wu, N. Permeability prediction in hydrate-bearing sediments via pore network modeling. Advances in Geo-Energy Research, 2025, 16(2): 158-170. https://doi.org/10.46690/ager.2025.05.07