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Simulation and optimization of a coupled reservoir and multi-phase flow network model
Get PDFThis 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
Non-monotonic evolution and spatial reorganization mechanism of thermally induced micro-damage in sandstone
Get PDFThis study employs transformative nanoscale-spatial methodology, which reveals the complete thermal damage evolution mechanism of sandstone from 25 to 700 ◦C, fundamentally challenging the conventional linear degradation paradigm. Spatial autocorrelation analysis is innovatively applied to atomic force microscopy data, establishing that thermal damage follows a non-monotonic pathway governed by spatial heterogeneity evolution rather than simple progressive weakening. Four critical temperature thresholds are identified: 200 ◦C marks the initiation of localized damage through expansion of weak zones with 61.4% stiffness reduction; 400 ◦C features unexpected transient hardening due to clay mineral dehydroxylation and pore restructuring, reaching the peak adhesion force; 500 ◦C represents not only increased damage but also the thermal decomposition of the 400 ◦C hardened structure, evidenced by maximum spatial heterogeneity and negative adhesion; and the 700 ◦C following quartz phase transition establishes a completely reconfigured structure with a novel "harder-in-lower-areas" pattern. Crucially, this research demonstrates that the spatial clustering of mechanical properties evolves from balanced high-low zones at 200 ◦C to a percolating low-stiffness network at 500 ◦C, establishing spatial reorganization as the governing principle of thermal damage. The findings provide a quantitative framework that can accurately predict rock behavior in geothermal systems and underground energy storage applications.Document Type: Original articleCited as: Yan, H., Zhou, T., Zhou, X., Liu, X., Tang, X. Non-monotonic evolution and spatial reorganization mechanism of thermally induced micro-damage in sandstone. Advances in Geo-Energy Research, 2025, 17(2): 135-148. https://doi.org/10.46690/ager.2025.08.0
Movable oil content evaluation in low-to-medium maturity lacustrine shale during in-situ conversion
Get PDFLow-to-medium maturity shale oil resources hold significant potential, but their economic accessibility is limited by low porosity, low permeability, and a low proportion of movable oil. In-situ conversion technology can crack organic matter and in-place oil into lighter molecules, enhancing oil and gas mobility and improving recovery rates. The success of this approach depends on dynamically evaluating the amount of movable shale oil during in-situ conversion. This study targets the lower submember of the fourth member of the Eocene Shahejie Formation (Lower Sha4 Member) in the Damintun Sag, Bohai Bay Basin, China. Through thermal simulation experiments, organic geochemical experiments, and nuclear magnetic resonance experiments, shale residual oil evaluation, organic matter hydrocarbon generation process evaluation, and dynamic evaluation of immovable oil were carried out. By integrating numerical simulations of the temperature field with the experimental results, a dynamic evaluation method for movable resources in shale during in-situ conversion was established. The findings indicate that the conversion rates of kerogen-to-oil and kerogen-to-gas first increase and then gradually stabilize as thermal maturity increases, with oil generation reaching its peak when the vitrinite reflectance reaches 1.0%. Long-term preserved shale samples were identified to contain immovable oil, the content of which increases with maturity before peaking and then declining. In-situ conversion of low-to-medium maturity shale in the upper part of the model can significantly increase movable oil resources in a year, potentially reaching the levels of extractable medium-to-high maturity shale. This work presented a crucial approach for assessing and improving in-situ conversion technology, providing a means of maximizing economic feasibility.Document Type: Original articleCited as: Bai, G., Chen, G., Cai, Z., Yan, H., Lu, S., Radwn, A. E. Movable oil content evaluation in low-to-medium maturity lacustrine shale during in-situ conversion. Advances in Geo-Energy Research, 2025, 16(1): 77-90. https://doi.org/10.46690/ager.2025.04.0
Experimental techniques for studying interfacial dynamics and sediment response during CH₄-CO₂ hydrate replacement
Get PDFMethane 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
A comprehensive review of shale wettability characterization: Mechanisms, measurements and influencing factors
Get PDFShale reservoir wettability is a critical parameter governing the occurrence, migration and recovery efficiency of oil and gas. However, its evaluation poses significant challenges due to the diverse mineral compositions, complex pore structures and varying temperature-pressure conditions prevalent in shale. This paper systematically reviews the recent advances in shale wettability assessment methods and their influencing factors. These factors are evaluated by various methods, each offering distinct advantages and limitations. The contact angle method provides rapid macroscopic wettability assessment but is constrained by the properties of mineral and fluid. Spontaneous imbibition effectively characterizes macroscopic wettability but is time-consuming owing to the inherently low porosity and permeability of shale formations. Nuclear magnetic resonance enables the dynamic monitoring of fluid distribution across multi-scale pores, whereas it is constrained by high technical complexity and cost. Numerical simulations investigate wettability from the perspectives of interfacial mechanics and at the molecular scale, while their parameterization and accuracy still depend on experimental validation. The spatial distribution of hydrophilic minerals alongside oleophilic organic matter leads to mixed-wettability states. Increased total organic carbon content enhances the oil-wetting propensity, while higher maturity further promotes the development of hydrophobic organic pores. Elevated temperature generally strengthens the water-wet characteristics, whereas increased pressure induces a preference for oil-wetting. High salinity fluids, particularly those containing divalent cations, asphaltenes and aromatic compounds, enhance oil affinity. Macroscopic wetting behavior is ultimately determined by the connectivity and relative abundance of organic versus inorganic pores. Although significant research has been conducted on shale wettability, its evaluation under reservoir conditions remains challenging. Future studies should integrate multidisciplinary approaches combining advanced experimental characterization with computational modeling to enhance dynamic wettability prediction under real reservoir conditions.Document Type: Invited reviewCited as: Jia, B., Yang, Y., Li, C., Wei, J., Rabatuly, M., Wang, L. A comprehensive review of shale wettability characterization: Mechanisms, measurements and inffuencing factors. Capillarity, 2025, 17(2): 38-53. https://doi.org/10.46690/capi.2025.11.0
Physical simulation and quantitative characterization of fault zones based on ring-shear experiments
Get PDFFault zones play a key role in controlling subsurface fluid migration, influencing hydro-carbon accumulation, CO₂ sequestration, and geo-energy storage safety. Most previous experimental studies, however, have been restricted to static outcrop or core observations, which fail to capture the progressive evolution of fault zone structures in time as a response to changing stresses. Moreover, existing analogue experiments often use unconsolidated sediments, which cannot accurately represent brittle faulting in consolidated rocks, and quantitative analyses remain limited. To address these challenges, a new method based on ring-shear experiments was developed to physically simulate fault zone formation in consolidated sandstones. The method simulates shear deformation under variable stress and displacement conditions, followed by multi-scale quantitative analyses, including computed tomography imaging, thin section analysis, and porosity-permeability testing under confining pressure. This comprehensive testing routine allows to quantify changes in fault zone thickness, particle and pore size distributions, and grain orientations during progressive deformation and depending on shear parameters. The results demonstrate systematic relationships between effective normal stress, shear displacement, and fault zone structural attributes. The fault zone thickness shows a nonlinear trend with stress, while cataclasis and compaction intensify with increasing displacement. This work provides a methodological foundation for future applications in fault seal analysis, fluid flow modeling, and numerical simulation, offering a practical reference for petroleum systems studies, hydrogeology, and underground gas storage including CO₂ and hydrogenDocument Type: Original articleCited as: Jiang, M., Jin, Y., Fu, X., Liu, Q., Misch, D. Physical simulation and quantitative characterization of fault zones based on ring-shear experiments. Advances in Geo-Energy Research, 2025, 17(3): 256-266. https://doi.org/10.46690/ager.2025.09.0
Microscale interaction mechanism between shale oil and CO2 in mixed wettability nanopores
Get PDFMicroscale interactions are pronounced in shale nanopores, while the relevant mechanisms between multiphase fluids remain unclear at present. In this paper, the CO2 displacement process in shale porous media with mixed wettability is simulated, with the aim to reveal the microscopic interphase mechanisms and assess CO2 displacement efficiency and storage performance. The results indicate that in the initial state, under the predominant effect of van der Waals forces, oil molecules are present in adsorbed and free states, while water molecules exist as films and clusters in the three types of channels, driven by the combined action of van der Waals forces, Coulomb forces and hydrogen bonds. During the displacement process, CO2 preferentially enters hydrophilic channels, followed by mixed-wetting channels, and finally lipophilic channels. Instantaneous dipole moments between non-polar molecules make van der Waals forces the dominant factor in mutual miscibility. The permanent dipole of polar molecules and the induced dipole of nonpolar molecules synergistically enhance the contribution of Coulomb force during the competitive adsorption process. However, the presence of “water bridge” within mixedwetting channels significantly inhibits CO2 penetration and impairs oil stripping. The final displacement efficiency and storage efficiency are 43.08% and 5.99%, respectively, both significantly lower than those in hydrophilic and lipophilic channels. This study clarifies the microscale interaction mechanisms in shale reservoirs with mixed wettability, offering practical guidance for effective shale reservoir exploitation.Document Type: Original articleCited as: Wang, F., Meng, X., Xu, H., Liang, Y., Liu, Y. Microscale interaction mechanism between shale oil and CO2 in mixed wettability nanopores. Advances in Geo-Energy Research, 2025, 18(3): 231-241. https://doi.org/10.46690/ager.2025.12.0
Wetting and injecting effects on CO₂ distribution: Pore-scale micromodel and simulation
Get PDFThe distribution of CO₂ is critical to the efficiency and stability of carbon storage; however, the roles of wettability and capillary number in controlling CO₂ distribution remain inadequately understood. In this study, visual waterflooding experiments and numerical simulations were performed using five homogeneous micromodels with distinct wettability characteristics to examine how wettability and capillary number influence CO₂ distribution during short-term waterflooding. The results demonstrate that both wettability and capillary number govern CO₂ distribution patterns and saturation. These patterns include continuous distribution, cluster-like distribution, and isolated bubbles. Both experimental and simulation data reveal that the total residual CO₂ saturation follows a non monotonic trend with increasing contact angle, while it increases as the capillary number decreases. As the capillary number varies, the displacement behavior transitions gradually from a stable displacement regime to a capillary fingering regime, resulting in variations in residual CO₂ saturation. With changing wettability, cooperative pore filling leads to fluid bypassing, thereby modifying the saturation of continuously distributed CO₂. In contrast, variations in the saturation of cluster-like and isolated bubble CO₂ are attributed to snap off mechanisms initiated by preceding film flow. This study elucidates how wettability and capillary number govern the residual trapping and distribution of CO₂ at the pore scale.Document Type: Original articleCited as: Shao, J., Wang, Z., Huang, B., Shi, X., Pan, Z., Misch, D., Zhang, K. Wetting and injecting effects on CO₂ distribution: Pore-scale micromodel and simulation. Advances in Geo-Energy Research, 2025, 18(2): 99-108. https://doi.org/10.46690/ager.2025.11.0
Evaluation of CO2 hydrate storage potential in the Qiongdongnan Basin via combining the phase equilibrium mechanism and the volumetric method
Get PDFCarbon dioxide capture, utilization and storage technology is considered to be one of the most effective strategies to mitigate CO2 emissions. In this process, CO2 that is injected into seabed sediments under specific temperature and pressure conditions is sealed in the form of CO2 hydrate, known for its high gas storage density and exceptional security features. This method has significant advantages compared with onshore geological storage schemes. Thus far, however, there has been no industrial demonstration of CO2 hydrate storage, and the CO2 hydrate storage potential in the South China Sea remains underexplored without targeted evaluations. In this study, the phase equilibrium mechanism is combined with the volumetric method to describe and evaluate the CO2 hydrate storage distribution range, effective thickness, and potential volume available for CO2 hydrate storage. Based on the latest exploration and development data from the Qiongdongnan Basin, along with geological structure data, multibeam bathymetry, local high-resolution three-dimension multichannel seismic reflection data, logging data, and submarine heat flow data, the distribution of the CO2 hydrate storage stability zone is determined. The results show that the effective thickness and regional scope of CO2 hydrate storage in the concerned area can be determined by virtue of the local water depths and the submarine temperature and pressure of 18 virtual wells. The minimum water depth in the Qiongdongnan Basin that satisfies the temperature and pressure conditions needed for CO2 sediment storage is established as 415 m. The theoretical geological storage capacity of CO2 hydrate in the Qiongdongnan Basin is determined as 5.75×1011 to 8.73×1011 t, where the value range of E is between 0.56 and 0.85. These findings offer a solid foundation for China to create, advance and execute a viable strategy for CO2 hydrate storage.Document Type: Original articleCited as: Zhou, X., Wu, S., Bosin, A. Chen, Y., Fang, X., Zhu, L. Evaluation of CO2 hydrate storage potential in the Qiongdongnan Basin via combining the phase equilibrium mechanism and the volumetric method. Advances in Geo-Energy Research, 2024, 11(3): 220-229. https://doi.org/10.46690/ager.2024.03.0
Deep learning in CO2 geological utilization and storage: Recent advances and perspectives
Get PDFDeep learning has been widely recognized in the field of CO2 geological utilization and storage applications. With the development of deep learning algorithms, intelligent models are gradually able to improve multi-source, multi-scale and multi-physicochemical mechanism barriers with high-fidelity solutions in practical applications. In this perspective, an overview of the traditional and state-of-the-art deep learning architectures involved in CO2 geological utilization and storage is outlined in terms of evolutionary trajectories. Meanwhile, the favorable directions and application scenarios of different deep learning algorithms for geo-energy intelligence modeling are summarized. Moreover, further insights into the future direction of deep learning burgeoning architectures in this f ield are provided. The physics-guided deep learning, explainable artificial intelligence, and generative artificial intelligence are expected to deliver more accurate solutions for information extraction and decision support within the CO2 geological utilization and storage communities.Document Type: PerspectiveCited as: Wang, Y., Chu, H., Lyu, X. Deep learning in CO2 geological utilization and storage: Recent advances and perspectives. Advances in Geo-Energy Research, 2024, 13(3): 161-165. https://doi.org/10.46690/ager.2024.09.0