This study addresses the fluid flash evaporation phase change in geothermal production wells. A forced circulation visual experimental platform was designed to investigate flow pattern evolution and differential pressure fluctuation characteristics during flash evaporation, and high-precision flow pattern recognition was achieved via signal decomposition and machine learning. Key steps include: constructing an experimental system with fluid dynamic control, temperature regulation, data acquisition, and a visual pipe section; recording flow patterns (bubble, slug, churn, annular flow) via high-speed photography and analyzing their triggering conditions/morphological features; collecting differential pressure signals (2~3 meters height) and identifying distinct amplitude-frequency-morphology characteristics among flow patterns; applying CEEMD to decompose signals and extract IMF energy spectra; and developing a PSO-LSSVM model using multi-parameters (inlet temperature, velocity, IMF spectra) for high-accuracy recognition. Results provide theoretical support for flash evaporation localization and severity assessment, aiding wellbore optimization and geothermal extraction efficiency improvement.

Multiscale energy and mass transport processes constitute the fundamental scientific foundation for sustainable geo-energy development and carbon neutrality. This perspective synthesizes cutting-edge advances in the field into three transformative thematic areas: thermodynamically consistent pore-scale modeling with robust numerical schemes that embed fundamental physical laws into mathematical formulations; molecular-scale insights and data-driven acceleration techniques bridging nanoscopic interfacial phenomena to reservoir-scale engineering; and coupled multiphysics-artificial intelligence frameworks for hydrogen infrastructure safety and supercritical CO₂ geothermal systems. Recent research reveals a paradigm shift toward living digital twins that integrate rigorous mathematical physics, multiscale computing, and artificial intelligence, charting a clear course toward carbon-neutral energy systems.

Pore-network models are widely used to describe pore-scale flow in porous media, and their reliability depends critically on accurate extraction of pore and throat structures. A new extraction framework, termed the topological pore-network finder, is proposed in this work, which combines topological data analysis, medial access path search, and flashlight search medial axis. The topological data analysis is used to identify pore connectivity and cluster the void space, thereby providing robust initial pore centers. The medial access path search method then traces strings between connected pore centers along the medial axis, while the flashlight search medial axis method is used to refine the resulting paths and improve computational efficiency. The method is validated using toy porous media, two- and three-dimensional digital rock samples. Sensitivity analyses show that the pore-network finder is stable with respect to image resolution and string discretization. Compared with the classical maximal-ball method, the pore-network finder achieves at least an order-of-magnitude acceleration while preserving the main geometric statistics and flow-response characteristics of the extracted networks. In addition, because the method operates in continuous space and can reuse information from previous states, it is well suited to quasi-dynamic updates during deformation. The pore-network finder therefore provides an efficient and accurate tool for pore-network extraction and subsequent pore-scale characterization in geo-energy systems.

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.

Multiphase flow in porous media is an important research topic in the field of oil and gas reservoir development. Due to the complex geological conditions in China, properties of rocks, such as permeability and porosity, are complex and heterogeneous. The numerical solution for the complex multiphase flow problems needs to overcome challenges such as the system’s multiple variables, strong nonlinearity, large computational cost, and the preservation of physical properties. For the traditional incompressible and immiscible two-phase flow model, the IMplicit Pressure Explicit Saturation (IMPES) semi-implicit scheme is a widely-used important algorithm for solving such problems, where the pressure equation is solved implicitly, and the saturation is updated explicitly. However, the traditional IMPES scheme requires the calculation of saturation gradients when updating the saturation. Therefore, it is not suitable for solving the two-phase flow problems in complex heterogeneous media. Hoteit and Firoozabadi proposed an improved IMPES method, allowing the method to reproduce discontinuous saturation in heterogeneous media. However, these two IMPES methods only update the saturation through the mass conservation equation of one phase of fluid, they cannot guarantee that the other phase of fluid also satisfies the local mass conservation property. The derivations of the pressure equations for these two IMPES methods are obtained by adding the volume conservation equations of each phase at the continuous level of partial differential equations, and then using incompletely matched spatial discretization methods for the pressure equation and the saturation equation. Therefore, it is impossible to simultaneously ensure the local mass conservation of each phase for the two-phase fluid. In this paper, based on several types of novel IMPES semi-implicit schemes for solving two-phase flow in porous media that we have published in recent years, we propose a new framework for deriving the pressure equation in IMPES. That is, we first discretize the volume conservation equation of each phase using a spatial discretization method with local conservation, and then add up the discretized volume conservation equations of each phase. In this way, a complete match in spatial discretization between the pressure equation and the saturation equation is achieved. Essentially, it overcomes the difficulty in previous literatures that the IMPES semi-implicit method cannot simultaneously ensure that both phases of the fluid satisfy local mass conservation. The novel IMPES method ensures that each phase of the fluid satisfies local mass conservation, the saturation is bounded, the computational scheme is an unbiased solution, and it is suitable for solving two-phase flow problem with different capillary pressure distributions in heterogeneous porous media. The novel phase-wise conservation IMPES framework proposed in this paper also has an advantage that the traditional IMPES does not have. That is, in the novel phase-by-phase conservation IMPES framework, it is only necessary to define the spatial discretization method of the volume conservation or mass conservation equation, and there is no need to separately define the spatial discretization method of the pressure equation. The solutions of several types of novel IMPES semi-implicit schemes that we have published in recent years can be regarded as special cases of the novel phase-by-phase conservation IMPES framework proposed in this paper. The IMPES framework in this paper can also be applied for more complex multi-component and multi-phase flow in porous media to construct more novel schemes. At the same time, through numerical examples of heterogeneous porous media, this paper verifies the effectiveness and superiority of the novel IMPES method in dealing with two-phase flow problems under complex geological conditions. Compared with the traditional method, it is more adaptable, more stable, and more efficient.