On November 16, 2025, the editorial office of Advances in Geo-Energy Research (AGER) successfully held the 100^th AGER Forum, jointly supported by several academic partners, and attended by more than 10,000 people online. With the theme focusing “Digital rock physics and fluid flow in the context of energy transition”, the event gathered renowned experts from UK, Belgium and China to discuss frontier progress in fluid flow, pore-scale simulation, and geo-energy storage research. The forum emphasized that digital rock physics and multiscale imaging technologies are becoming essential research tools in next-generation low-carbon energy systems. The AGER forum included expert lectures and interactive discussions, enhancing the influence of AGER within the global geo-energy field. The 100^th Forum marks an important milestone in the development of the journal. In the future, the AGER Forum will continue serving as a platform for advancing science and technology in the field of geo-energy.

The alteration of oilwell cement due to H₂S poses a significant threat to wellbore structural integrity in geothermal environments. However, laboratory studies on the cement deterioration process caused by H₂S flow along a leaking channel under high-temperature conditions remain scarce. In this study, computed tomography (CT) scanning was utilized to assess the morphological changes and alteration patterns of oilwell cement caused by H₂S flow in multiple dimensions. Additionally, scanning electron microscopy (SEM) coupled with energy-dispersive X-ray spectroscopy (EDS) and Fourier transform infrared spectroscopy (FTIR) were applied to elucidate the microscale mechanisms responsible for the H₂S-driven alteration. The results show that: H₂S flow along the cement channel results in increased cement matrix porosity and formation of large pores, which are especially evident in regions adjacent to the channel. Chemical etching and secondary crystal growth contribute to the expansion of channel dimension and roughening of the channel wall. Consequently, the permeability of the cement matrix exhibited a marked increase of 45% over a period of 14 days. At the microstructural level, compared to unaltered oilwell cement, which exhibits a homogeneous texture and fine particle composition, exposure to H₂S leads to the formation of a heterogeneous and fractured structure within the cement. As a result of sulfidation reactions, a surface layer approximately 1 mm in thickness forms on the cement, which is depleted in calcium and enriched in silicon. The identification of metallic sulfides elucidated the chemical mechanisms responsible for the deterioration of cement properties. In summary, the flow of H₂S through the channel within the cement causes significant alteration of the cement structure compared to other alteration modes.

Enhanced CO₂ mineralization and geologic CO₂ storage have received increasing attention as two prominent approaches in combating climate change and fostering sustainable development of human society. This paper aims to explore three emerging areas of research within the realm of enhanced CO₂ mineralization and geologic CO₂ storage, including enhanced rock weathering, numerical modeling and validation of CO₂ storage accounting for the interplay of various trapping mechanisms, and the examination of how reservoir heterogeneity influences the migration of CO₂-brine multiphase flow. Discussions highlight the effectiveness of the spectrum induced polarization for monitoring changes in petrophysical and geochemical properties of rocks during enhanced rock weathering. Additionally, the multi-scale heterogeneity of geological formations needs to be carefully characterized, due to the fact that it plays a vital role in CO₂ migration. Further research is required to achieve accurate and reliable simulations of convective mixing for field-scale applications.

CO₂ geological utilization and storage is considered as an effective approach to deeply cut anthropogenic CO₂ emissions. It is vital to enhance the amount of CO₂ stored in the subsurface, at the same time to ensure safe and long-term subsurface storage of CO₂ without any CO₂ leakage. Science and engineering research in modeling concepts, experimental approaches, safety assurance and emerging CO₂ geological utilization and storage technologies have driven the advancement of CO₂ geological utilization and storage in recent years. In order to encourage communication and collaboration in CO₂ geological utilization and storage research worldwide, a Sino-German joint symposium titled “Opportunities and Challenges in CO₂ Geologic Utilization and Storage” was organized in Wuhan and Stuttgart from February 22 to 24, 2023, bringing together experts from China, Germany, and other countries. The symposium was jointly organized by Institute of Rock and Soil Mechanics, Chinese Academy of Sciences and Institute for Modelling Hydraulic and Environmental Systems, University of Stuttgart with financial support from the Sino-German Center for Research Promotion. A two-site hybrid meeting was held (participants in China met in Wuhan, participants in Germany met in Stuttgart, and other participants joined the meeting online), attracting more than 100 participants from around the world. The latest studies in the field of CO₂ geological utilization and storage were presented at the symposium.

A thorough understanding of the microscopic flow process in porous and fractured media is significant for oil and gas development, geothermal energy extraction and subsurface CO₂ storage etc. In CO₂ geological sequestration, the CO₂ is often injected at the supercritical state (scCO₂), which will displace the connate fluids in the pore spaces during the drainage process. However, when CO₂ injection stops, the connate brine or water flows back to displace the scCO₂. Therefore, the configuration of migration paths in a specific reservoir plays a significant role in affecting the connectivity and storage efficiency of scCO₂. In this paper, the two-phase (scCO₂ and water) boundary has been defined using the phase field method, and the COMSOL Multiphysics simulator is applied to study the migration of scCO₂ in porous/fractured media at the pore scale. The geological conditions of Shiqianfeng formation in the CO₂ capture and storage pilot site of the Ordos Basin in China is selected as the engineering background. Before using the actual microscopic geometry based on thin-section of Shiqianfeng sandstone, we get the general understanding on scCO₂ migration in fractured porous media that has the highly simplified configuration with circular particles, considering the impacts of wettability, geometry of formation mineral grains, interfacial tension, injection rates, and fracture geometry. Results show that the CO₂ preferential flow occurs at locations with high CO₂ flow rates and high CO₂ pore pressure. The preferential flow of scCO₂ occurs adjacent to the wall of grains while minimal or little flow takes place through the interior between the grains, considering the grains with irregular shapes. The interfacial tension of porous media plays a significant role in controlling the spatial distribution of the scCO₂. A much lower interfacial tension results in a much thinner scCO₂ flow band with a much higher saturation. The geometry of fractures in porous media increases the complexity of the scCO₂ flow paths at the pore scale.