Saturation-functions models in CO2-brine system: A comparative study

CO2 injections into deep saline aquifers create a multiphase flow system within the porous media. In this context, relative permeability and capillary pressure, as saturation functions, are key parameters that control flow dynamics, simulation accuracy, and operational decisions. Since various models have been proposed for the saturation functions, this study aims to assess the existing models and investigate which model performs best under different circumstances. To this end, we first gathered a comprehensive data set to evaluate the existing models. Following that, the nonlinear fitting of experimental data was used to obtain the parameters of each model. Finally, the root-mean-square error and correlation coefficients were used to assess the accuracy of the fit. Based on the results of capillary pressure analysis, the models can be classified into two main categories. The first category includes models with power-law behavior suitable for homogeneous formations (single curvature), such as Brooks-Corey, Li-Horne, Lambda, Thomeer, Leverett J-function, and modified J-function models. The second category includes Van Genuchten, Kosugi, Skelt-Harison, Johnson, and Jing-Van Wunnik, which can be applied to homogeneous and heterogeneous formations (capture more than one curvature). Regarding relative permeability, the L.E.T., Chierici, Van Genuchten, and Corey models exhibit comparable performance across all scenarios. Corey offers simplicity with minimal parameters, while Van Genuchten provides more adaptability for complex data sets with more physically based parameters.Document Type: Original articleCited as: Faramarzi, M., Tabatabaei, S. M., Sedaee, B., Attari, N., Panahi, S. A. Saturation-functions models in CO2-brine system: A comparative study. Capillarity, 2025, 14(2): 35-52. https://doi.org/10.46690/capi.2025.02.0

Recent progress of coal seam water injection technology for dust prevention: A comprehensive review

Coal seam water injection constitutes a fundamental measure for ensuring safe and efficient coal mine production, preventing pneumoconiosis hazards, and protecting the environment. However, systematic reviews integrating its dust reduction theories and technologies remain scarce. This paper reviews the foundational theories and technological advancements in coal seam water injection for dust control, revealing the regulatory mechanisms of dust reduction through coal’s seepage-wetting behavior from dual perspectives of the internal structural features of coal and the evolving stress-water pressure environment. Additionally, it evaluates the technologies for modifying coal’s physical properties and technologies for injected fluids modification. Finally, it identifies the challenges faced by coal seam water injection technology and proposes future research directions. Our review found that pore-fracture network connectivity governs water transport pathways, while dynamic equilibrium between interfacial tension and chemical group interactions determines wetting efficiency at the microscopic level. Macroscopically, hydro-mechanical coupling effects induce multi-stage fracture network evolution through stress redistribution, forming multi-level interconnected topological structures that significantly enhance wetting homogeneity. From a technological perspective, this study establishes a geology-adaptive technical framework based on coal seam characteristics and physicochemical parameter compatibility. The review promotes the transition of water injection technologies from experience-driven “extensive pressurization” to data-driven “precision wetting,” providing a theoretical foundation for developing safe, green, intelligent, and source-controlled dust reduction technologies.Document Type: Invited reviewCited as: Wang, H., Wang, H., Tan, J., Du, J., Zhou, W., Zhang, Y. Recent progress of coal seam water injection technology for dust prevention: A comprehensive review. Advances in Geo-Energy Research, 2025, 16(3): 181-198. https://doi.org/10.46690/ager.2025.06.0

On multi-block lattice Boltzmann method for high Knudsen number flows

This work introduces a new computational framework aimed at advancing the modeling of gas transport in confined porous media, particularly shale and tight geological formations that are characterized by their intricate network of meso- and micro-scale fractures and a broad distribution of organic pores. Accurate simulation of gas behavior in such media is challenging due to the complex interactions occurring at high Knudsen numbers, where conventional continuum-based methods fail and kinetic-theory approach becomes more suitable. To tackle these complexities, this work presents a lattice Boltzmann framework tailored for large computational domains with multi-scale pore structures from nano to micro scales. This framework incorporates slip boundary conditions and features an innovative multi-block approach to enable efficient simulations over a wide range of pore sizes, from nanometers to micrometers. The novel contributions of this work include: A scale-informed grid refinement strategy, the incorporation of shear stress terms, multi-block evolution algorithm, and a novel classification method for implementing specular reflection boundary conditions on irregular surfaces. Validation against Direct Simulation Monte Carlo and Molecular Dynamics data from the literature confirms the model’s accuracy in predicting gas behavior. Simulations of methane transport in tight porous media with irregular geometries highlight the framework’s effectiveness in modeling gas permeability across varying pressure conditions. Apparent permeability results across a range of Knudsen numbers demonstrate the versatility of this framework in capturing the physics of gas transport in confined porous media.Document Type: Original articleCited as: Rustamov, N., Mostaghimi, P., Aryana, S. A. On multi-block lattice Boltzmann method for high Knudsen number flows. Advances in Geo-Energy Research, 2025, 16(2): 143-157. https://doi.org/10.46690/ager.2025.05.0

Experimental techniques for studying interfacial dynamics and sediment response during CH₄-CO₂ hydrate replacement

Methane hydrates are a largely untapped energy resource with the potential to support carbon sequestration through CH₄-CO₂ exchange. However, large-scale methane recovery from hydrate-bearing sediments remains constrained by key uncertainties related to sediment stability, multiphase fluid dynamics, and geomechanical responses during gas production. One of the key scientific challenges is to understand the transient interface dynamics and mechanical weakening of hydrate deposits during CH₄-CO₂ displacement, especially the unexplained effects of pore water meniscus surface evolution and its influence on sediment stability. This study reviews CH₄-CO₂ replacement methods, including microscale piezoelectric sensing, triaxial testing, and real-time resistivity monitoring. It quantifies displacement efficiency and hydrate dissociation geomechanics while analyzing interfacial dynamics and sediment behavior during exchange process.Document Type: PerspectiveCited as: Cao, S. C., Li, X., Jung, J., Li, X. Experimental techniques for studying interfacial dynamics and sediment response during CH₄-CO₂ hydrate replacement. Capillarity, 2025, 15(3): 53-57. https://doi.org/10.46690/capi.2025.06.0

Shale oil micro-migration characterization: Key methods and outlook

Research has identified and increasingly explored the micro-migration phenomenon in shaly strata, which is currently one of the key scientific issues affecting shale oil accumulation and efficient development. Recently, qualitative and quantitative methods for characterizing hydrocarbon fractionation related to shale oil micro-migration have been proposed, which brought promising prospects to oil micro-migration research. Three key techniques in this field are summarized in this minireview, and the outlook for shale oil micro-migration characterization is prospected. Fourier transform ion cyclotron resonance mass spectrometry can be employed to distinguish subtle composition differences related to short-distance migration; core-flooding extraction experiments can be utilized for the quantitative characterization of micro-migration in organic-rich shale; and semi-open thermal simulation experiments are useful to analyze the chemical composition and structural evolution of expelled and retained oil. These three methods have different focus and advantages, while they provide different viewpoints and means for the characterization of shale oil micro-migration and have all achieved good results in different regions. Studies regarding the latest technologies deepen our understanding of the short-distance migration of shale oil, as well as improve our knowledge of the mechanisms of shale oil micro-migration, which is of great practical significance to the evaluation of shale oil content and mobility and further optimizes the identification of sweet spots and the effects of fracturing development.Document Type: Current minireviewCited as: Hu, T., Jing, Z., Zhang, Q., Pan, Y., Yuan, M., Li, M. Shale oil micro-migration characterization: Key methods and outlook. Advances in Geo-Energy Research, 2025, 15(1): 5-12. https://doi.org/10.46690/ager.2025.01.0

Methane hydrate formation characteristics under different initial conditions and their impact on coal seam propertie

Due to the unique structural characteristics of hydrate, it has a potential application value in coal and gas outburst prevention in coal mines. Given the complexity of subsurface environments, it is essential to investigate the hydrate formation kinetics under varied initial conditions, as well as the subsequent impacts of hydrate formation on coal seam properties. This research mainly focuses on the hydrate formation process in coal samples with different coalification degrees under different initial pressure and water saturation conditions by using the designed hydrate formation system. The results show that gas consumption and hydrate saturation can be greatly enhanced by increasing the initial water saturation and pressure, which is favorable to reduce the coal seam gas pressure and improve the coal seam peak strength. The calculation results suggest that hydrate formation at varying saturation reduces the gas pressure by 53.05% ∼91.33% and increases the peak strength of coal across the tested confining pressure by 36.45% ∼ 59%. Furthermore, this study found that hydrate formation kinetics are significantly enhanced in lignite compared to that in anthracite, which may be attributed to structural variations associated with the coalification degree. The underlying mechanism requires further research in the future. The data obtained in this study regarding the effect of hydrate formation under different initial conditions on coal seam properties demonstrate the feasibility of preventing gas disasters in coal via controlling the initial conditions.Document Type: Original articleCited as: Sun, C., Liu, S., Li, S., Wang, K., Dong, Z., Kong, S. Methane hydrate formation characteristics under different initial conditions and their impact on coal seam properties. Advances in Geo-Energy Research, 2025, 16(3): 229-243. https://doi.org/10.46690/ager.2025.06.0

Simulation and optimization of a coupled reservoir and multi-phase flow network model

This work considers a coupled system of the MATLAB Reservoir Simulation Toolbox, a multi-phase network simulator and topside processing facilities, with the intent to provide a research tool for studying integrated planning and optimization. To this end, a collection of open-source tools are presented that can be combined with MATLAB Reservoir Simulation Toolbox to model, evaluate and optimize the economy of integrated systems, including reservoir and network under different market (costs and revenue) scenarios. The tools are organized in four repositories containing code for cost/price scenario modelling, derivative-free trust region optimization, pipe/network simulation and reservoir-network coupling and examples. A brief background on each of these tools is given, followed by the presentation of a fully implicit approach for the reservoir-network coupling. Moreover, a description is given on how to set up coupled simulation models, and finally, a presentation of numerical examples, including an optimization example that utilizes the full set of above-mentioned tools.Document Type: Original articleCited as: Leinan, P. R., Ustad, T. S., Krogstad, S., Silva, T. L., Ortiz, M. M., Hellemo, L., Smith, I. E. Simulation and optimization of a coupled reservoir and multi-phase flow network model. Advances in Geo-Energy Research, 2025, 15(3): 203-215. https://doi.org/10.46690/ager.2025.03.0

Design and experimental performance evaluation of high-temperature and high-pressure test platform for deep in-situ fidelity coring tools

With the increasing mining depth of mineral resources, the temperature and pressure of the underground environment are also on the rise, which puts forward strict requirements for the performance of fidelity coring tools. To promote the development of such tools, a comprehensive high-temperature and high-pressure test platform for deep in-situ fidelity coring tools was constructed, and its working principle was described in detail. In addition, four key functional modules of the test platform were developed. On the basis of the principle of gas-liquid pressurization and the burst failure criterion of pressure vessel, a mechanical module integrating the functions of pressurization and pressure maintaining was designed. The heating and insulation module was developed by using a U-shaped high-speed heater and electromagnetic induction heating technology. The innovation utilized coil cooling technology to achieve effective cooling and pressure relief. Furthermore, the working performance of the test platform was studied experimentally. The designed test platform could run stably for more than 110 min under test conditions of high pressure and temperature of 140 MPa and 150 ◦C, respectively, and it could maintain a stable pressure and temperature at 200 MPa and 160 ◦C for more than 182 min. Under the high-pressure condition of 220 MPa, the pressure remained stable within 140 min, without any fluid leakage. Therefore, the test platform designed in this study can provide experimental conditions of high pressure and high temperature for the research of fidelity coring tools, which is of great significance for the accurate evaluation and safe exploitation of deep mineral resources.Document Type: Original articleCited as: Huang, W., Li, J., Yang, Y., Liu, Z., Shang, D. Design and experimental performance evaluation of high-temperature and high-pressure test platform for deep in-situ fidelity coring tools. Advances in Geo-Energy Research, 2025, 15(1): 55-67. https://doi.org/10.46690/ager.2025.01.0

Fault-controlled oil and gas reservoir unit division based on graph

Research on reservoir-unit division in fault-controlled oil and gas reservoirs is essential for analyzing reservoir hydrocarbon migration and accumulation. Currently, most research on reservoir-unit division has focused solely on the identification of faults and caves, employing three-dimensional spatial visualization or other methods for a simple analysis of their links. However, these approaches often lack a reasoning process that exploits the links between faults and caves for deeper insights. For such complex oil and gas reservoirs, a systematic analysis based on the interrelations between multiple geological factors is needed. Therefore, this paper proposes a graph-based method for reservoir-unit division in fault-controlled oil and gas reservoirs, enabling the representation of links between faults and caves, and it presents further systematic analysis to derive the reservoir-unit division results. A multi-attribute graph-clustering-based fault-extraction method is utilized to achieve comprehensive fault representations as fault entities. More reliable cave-instance segmentation results are obtained through attribute fusion, representing cavity entities. A graph incorporating fault and cave entities is then created. Fault entities are classified into several levels according to their spatial scale, and directed edges are utilized to represent connectivity links between faults and caves. Moreover, a connectivity analysis centered on caves was conducted using the created graph. Based on existing reservoir unit knowledge and the cave-connectivity analysis results, reservoir-unit division was achieved. The proposed method provided reservoir-unit division results highly consistent with the information contained in seismic data, offering a new perspective for multielement integrated analysis in geophysical exploration.Document Type: Original articleCited as: Zhou, C., Fei, Y., He, X., Cai, H., Yao, X., Hu, G. Fault-controlled oil and gas reservoir unit division based on graph. Advances in Geo-Energy Research, 2025, 15(1): 68-78. https://doi.org/10.46690/ager.2025.01.0

Field-scale investigation of CO2 plume dynamics under spatial wettability variations: Implications for geological CO2 storage

Subsurface formations typically exhibit heterogeneous wetting characteristics due to the complex pore system, mixed lithology, and prolonged contact with native fluids. This non-uniformity in spatial wettability distribution thus makes the subsurface formations exhibit more complex localized CO2/brine/rock interactions, introducing uncertainties in estimating trapping capacity and predicting CO2 plume migration. Field-scale investigation on the role of wettability in CO2 geo-storage has received limited attention, and previous studies typically assume an internal uniform wettability condition across the whole formation. However, the more realistic scenario of internal wettability spatial variations within a single formation is yet to be thoroughly examined. In this study, a range of experiment-derived wettability-dependent trapping coefficients were utilized to implement the internal wettability heterogeneity in a single formation model, and its impact on CO2 plume pattern and trapping efficiency was examined. Furthermore, mixed-wet systems with different CO2-wet fractions were also considered in this study. The results indicate that internal wettability variations result in changes in the local CO2 saturation pattern and thus impact the overall plume shape and migration. In addition, the internal heterogeneous wettability system exhibits an approximately 35% reduction and an approximately 20% increase in residual trapping capacity in comparison to internal uniform strongly water wet and uniform weakly water-wet systems, respectively. An increase in the fraction of CO2-wet regions in the mixed-wet system results in concentrated high-saturation clusters and reduced local CO2 residual saturation. This further results in reduced residual and dissolution trapping, followed by a linear correlation.Document Type: Original articleCited as: Zhang, H., Mahmoud, M., Iglauer, S., Arif, M. Field-scale investigation of CO2 plume dynamics under spatial wettability variations: Implications for geological CO2 storage. Advances in Geo-Energy Research, 2025, 15(3): 230-244. https://doi.org/10.46690/ager.2025.03.0