Orals: Thu, 1 May | Room -2.43
Shale reservoirs are recognized for their ability to serve as natural barriers for conventional hydrocarbons and their suitability for CO₂ sequestration, owing to their organic-rich composition and intricate pore structures. This study investigates the shales of the Barakar Formation in the Mand Raigarh Basin, India, to evaluate their potential for CO₂ storage by analyzing factors influencing pore volume and surface area. A comprehensive suite of analytical techniques—XRD analysis, Rock-Eval pyrolysis, and low-pressure gas adsorption using N₂ and CO₂ probes—was employed to assess mineralogy, organic matter content, and pore characteristics. Thermal maturity assessments revealed that the shales are transitioning from immature to marginally mature stages, with kerogen types reflecting a mix of gas-prone and oil-prone organic matter. Mineralogical analysis highlights the predominance of clay minerals, alongside other components influencing shale composition. High-resolution 2D imaging offers a detailed understanding of pore structures, emphasizing the role of organic matter and clay minerals in controlling gas adsorption behaviour. Mesopore development was strongly associated with clay minerals, while organic matter predominantly governed micropore formation. Fractal analysis revealed the complexity of pore morphologies, showing higher irregularity in smaller mesopores than larger ones. These findings underscore the intricate relationship between mineralogical and organic components in determining the suitability of Barakar Formation shales for CO₂ sequestration. By integrating insights into thermal maturity, organic composition, and pore structure, this study highlights the Barakar Formation shale’s significant potential as a secure and efficient CO₂ storage site, contributing to climate change mitigation, sustainable resource management, and a deeper understanding of shale's role in carbon sequestration. This work contributes to climate change mitigation strategies by leveraging the structural and compositional characteristics of shale formations for carbon management. The results align with global sustainability objectives, transforming shales from traditional energy resources into effective tools for reducing atmospheric CO₂ levels, thereby bridging energy needs with environmental management.
How to cite: Ghosh Dastidar, S., Sarkar, K., Chandra, D., Hazra, B., and Vishal, V.: "Shale Reservoirs as Potential CO₂ Storage Sites: Exploring Mineralogical and Organic Interactions", EGU General Assembly 2025, Vienna, Austria, 27 Apr–2 May 2025, EGU25-3402, https://doi.org/10.5194/egusphere-egu25-3402, 2025.
This study investigates the usefulness of fractal dimension for assessing fracture network geometry especially, in terms of connectivity in petroleum and geothermal reservoirs. We evaluated connectivity using both static and dynamic approaches and analyzed a set of fractal-fracture models and outcrop maps. The models comprise a deterministic fractal-fracture network and a set of thirty random fractal-fracture networks, all sharing the same fractal dimension. The natural dataset includes a series of nested network maps from an outcrop analog. These maps have been studied for their fractal nature, clustering behavior, and flow properties. For the “static” approach, connectivity of the fracture networks is evaluated by considering three different “nodes” in each of the networks, i.e., cross-cutting (X), abutting (Y), and isolated (I). In considering a “dynamic” approach for evaluating connectivity, the flow response is computed along with the integrated “time-of-flight” (TOF) at different time-steps. The networks are converted into simulation-ready fracture continuum models that were run in a streamline flow simulator, TRACE3D. The TOF plots thus generated provide insights into the connectivity between injection and production wells placed at diagonally opposite corners of the flow domain and are used to evaluate flow pathways and the effects of reservoir heterogeneity. They also implicitly indicate the “percolation connectivity” of a fracture network. This may be confirmed by comparing previously reported values of “percolation connectivity” of the outcrop analogs and the TOF plots. The ultimate goal of this research is to determine whether the fractal dimension can serve as a unique identifier for the connectivity of fracture networks. The results derived from both fractal-fracture models and natural maps indicate otherwise. The findings from this study can improve decision-making across various fields, including hydrogeology, resource management, and environmental engineering, leading to more effective strategies for resource extraction and risk reduction.
How to cite: Roy, A., Sahu, A. K., Biswas, R., and Sahoo, B.: Connectivity and Fractal Dimension of Fracture Networks, EGU General Assembly 2025, Vienna, Austria, 27 Apr–2 May 2025, EGU25-9983, https://doi.org/10.5194/egusphere-egu25-9983, 2025.
Building high-quality reservoir models that integrate geological and petrophysical properties is a complex task. The primary modeling process involves creating two-dimensional maps of porosity and either absolute or effective reservoir permeability using results from well-log interpretations and laboratory measurements of core samples. Often, the petrophysical relationship between rock porosity and permeability is adjusted, and variograms used for spatial correlation are fine-tuned to reconcile with the measurements. However, such adjustments make it challenging to address significant errors in permeability, which can vary dramatically, spanning several orders of magnitude within a geological formation. In energy security and environmental conservation scenarios—such as enhanced oil recovery (EOR), shale gas production, enhanced geothermal systems, and geological CO2 storage (GCS)—fluid injection typically results in a permeability drop of 35-86% around the injection well. This reduction can impede the injection process and lead to unnecessary remediation costs. Storage capacity, indicated by porosity, and injection efficiency, governed by permeability, are critical criteria for characterizing GCS sites. Therefore, accurate quantification of permeability is essential. Quantitative permeability modeling holds the key to unlocking the questions about fluid flow direction in hydrocarbon reservoirs, especially in the face of limited measurements from core samples or Well tests. Permeability is strongly influenced by pore-scale heterogeneities, which range from nanometers to micrometers (µm), and the evaluation of these heterogeneities varies depending on the scale considered in Euclidean geometry. This study will present a method based on scale-invariant or fractal geometry to predict reliable permeability and will validate these predictions with core-scale measurements. Additionally, the significance of permeability maps in EOR and GCS studies for forecasting fluid flow directions within a reservoir will be examined through two case studies. Finally, the discussion will include future directions for incorporating ultra-small heterogeneous effects (less than 0.1 µm), which are often overlooked due to observational and mathematical-model limitations.
How to cite: Vadapalli, U.: Permeability modeling for Enhancing Resource Utilization, EGU General Assembly 2025, Vienna, Austria, 27 Apr–2 May 2025, EGU25-210, https://doi.org/10.5194/egusphere-egu25-210, 2025.
The world is striving to achieve net-zero carbon emissions at the earliest possible time. Geothermal energy is one of the renewable energy playing a significant role with its sustainable, consistent and potentially affordable in generating the power and competence in production of green hydrogen. Magnetotellric (MT) method is an excellent way to detect caprock, geothermal fluids and source based on the resistivity models. India’s geothermal resources discloses extensive large number of geothermal provinces with promising energy prospects. However, the present study deals with most promising geothermal province Puga and Chumathag are located in the Indo-Eurasia tectonic collision boundary of NW Himalayan region (altitude ~ 4500m). It is composed of different rock types such as plutonic, basic to ultrabasic, and submarine volcanic rocks (Ophiolites). The Puga valley consists of Precambrian paragneisses, schists, carbonates (Tanglang La) and limestone where as Chumathang region comprises of thick sequence of shallow marine to fluvial deposits of Kuksho formation related to Indus group. A total of 62 MT stations were used in Puga-Chumathang geothermal region to understand the shallow crustal architecture in terms of significant linkage of geothermal fields. The geoelctrical structure derived from the 3D inversion of MT data highlights the different fault structures, lateral extent and upward migration of geothermal fluids at Puga and Chumathang geothermal zones. The study also highlights the presence of secondary magma at a shallow level abducted from Indus Suture zone acts as a possible heat source for these hot springs. 3D MT model along with in observation of negative free air gravity anomaly structural trend signifies the presence of low density material supports the link between both the hot springs. This result greatly helps new pathways in advancing the large-scale plan for geothermal prospecting in India.
How to cite: Pachigolla, V. V. K., Patro, P. K., Azeez, K. K. A., Kadukuntla, C. R., Babu, N., and Mothukuri, S.: Relevance of magnetotelluric method to unlock renewable geothermal energy, A case study from Puga-Chumathang geothermal zone, NW Himalaya, India, EGU General Assembly 2025, Vienna, Austria, 27 Apr–2 May 2025, EGU25-405, https://doi.org/10.5194/egusphere-egu25-405, 2025.
Geothermal energy refers to the energy derived from the Earth’s heat and is a promising renewable resource, that can be harnessed for electricity generation, direct heating, and other industrial applications. Although geothermal energy has been utilized for various applications in several parts of the world for decades, its potential remains largely untapped in India. India’s geothermal energy development is still in the nascent stage compared to other renewable resources like solar and wind. However, given the country's growing energy demand and commitment to sustainable energy solutions, geothermal energy could play an important role in the coming future.
Over the last few decades, the identification of surface manifestation, followed by geological, geochemical, and geophysical investigations by the Geological Survey of India, the National Geophysical Research Institute, and many other organisations, demarcated ten geothermal provinces in India. Studies indicate that geothermal potential in India is mostly concentrated in the hot spring regions, which are connected to the deep geothermal reservoir by fault and fracture systems. These need to be explored further for exploitation based on their reservoir potential and sustainability.
In recent years, the Government of India has taken initiatives to carry out detailed geothermal exploration, which will be followed by exploitation in most potential zones. Based on the knowledge, three regions have been identified, and work is in progress by various research organisations and government/private institutions for exploration and exploitation. These are (i) Puga-Chumathang-Panamik in the Ladakh Himalayas, (ii) Tattapani in Central India, and (iii) Manuguru in the Godavari Gondwana basin. Hydrogeochemical and multiparametric geophysical investigations are underway in the above regions. Recent thermal, geological, and hydrogeochemical results, along with the previous knowledge from the Ladakh Himalaya and Central India indicate spatial distribution of the geothermal reservoir with medium to high enthalpy geothermal potentials. This will be followed by drilling exploratory wells, to constrain various geothermal parameters. These efforts mark a critical step towards harnessing India’s geothermal resources for sustainable energy production.
How to cite: Ray, L., Chopra, N., Dutta, A., Kurakalva, R. M., Sidagam, E. R., Podugu, N., Prajapati, S. K., Dudhate, A. P., and Satyanarayanan, M.: Geothermal Energy in India: Current Status and Future Prospects, EGU General Assembly 2025, Vienna, Austria, 27 Apr–2 May 2025, EGU25-15315, https://doi.org/10.5194/egusphere-egu25-15315, 2025.
Flooded coal mines have the potential to provide low-carbon renewable heating, independent of surface weather and temperature conditions. To develop an open-loop mine water heating system, it is essential to estimate the amount of heat available within the mine. This estimation is necessary to determine the potential size of the system, assess whether it meets surface demand, and evaluate its economic viability.
Various methods can be used for this estimation. Static methods, which do not account for the influence of time or the underground spatial geometry, rely on simplified variables. These include calculating the background heat flow over the mine's area, estimating the heat stored in the rock volume surrounding the mine, assessing the heat in the mine's water volume, and determining a realistic flowrate to calculate the potential heat extraction.
In contrast, dynamic modelling methods provide a more comprehensive approach by accounting for changes in heat availability over time and the mine's structural architecture.
Using the GEMSToolbox, we performed dynamic modelling on a real two-seam coal mine map and a simplified grid model with comparable size and properties. The results from these dynamic models were compared with static methods, revealing significant differences in heat estimates, varying by orders of magnitude from 1010 MJ to 103 MJ of heat produced over 40 years.
Dynamic modelling also offers additional benefits, such as tracking heat variation over time, analysing the impact of different injection and abstraction points, and assessing potential interference from nearby geothermal systems. These findings underscore the advantages of dynamic modelling in developing and optimising mine water heating systems.
How to cite: Sweeney, A., van Hunen, J., Mouli-Castillo, J., and Gluyas, J.: Dynamic vs static assessment of the mine water heat energy potential of coal mines, EGU General Assembly 2025, Vienna, Austria, 27 Apr–2 May 2025, EGU25-8295, https://doi.org/10.5194/egusphere-egu25-8295, 2025.
Mine water in disused flooded coal mines is a potentially valuable low carbon heat source. This mine water must be resilient to the impacts of climate change. Changes in temperature and rainfall could affect mine water resources, but the range of impacts and, crucially, whether they are negative or positive – and how they are developed and operated – have not been researched to date. This research is investigating, for the first time, the impacts of climate change on mine water resources.
To understand these impacts, we work at two mine water heat prospect case study locations in Central Scotland. We selected one on the east coast and one on the west coast to investigate and account for different rainfall patterns. Since May 2023 we have been undertaking field monitoring and subsequent lab analysis to examine seasonal and longer-term changes. In the field, we analyse mine water levels/recharge, chemistry, temperature, and gases (CO2 and CH4). In the lab we test for parameters that could be affected by climate change e.g. conductivity, total dissolved solids; a minimum mine water suite e.g. iron; and a standard suite of anions and cations. Additionally, to expand our geographical and temporal coverage, we are collating secondary data from sources including the Mining Remediation Authority, UK Geoenergy Observatories (UKGEOS), and the Scottish Environmental Protection Agency (SEPA).
Here, we present (a) an assessment of potential impacts of climate change on mine water, (b) early insights into seasonal variation and potential causes and impacts, (c) emerging implications, and (d) future work.
How to cite: Gillen, C., Burnside, N., McGrane, S., and Roberts, J.: Investigating the potential impacts of climate change on mine water resources: Central Scotland as a case study., EGU General Assembly 2025, Vienna, Austria, 27 Apr–2 May 2025, EGU25-1347, https://doi.org/10.5194/egusphere-egu25-1347, 2025.
In response to growing climate targets and the need for innovative heat management solutions, Durham University, UK, is investigating the reuse of waste heat generated by its high-performance computing (HPC) data centre, which produces up to 1.5 MW of heat. This project explores the potential of repurposing abandoned, flooded mine workings beneath the campus for seasonal thermal energy storage. The system aims to capture surplus heat during the summer and store it within mine water reservoirs for reuse in winter coupled with heat pump technology for building heating, reducing emissions and investigating potential enhancement of campus-wide sustainability.
The Immersion Cooling and Heat Storage (ICHS) projectaddresses critical technical challenges: understanding subsurface water flow dynamics, determining heat injection and retrieval efficiencies, and optimizing borehole configurations between shallower and deeper worked coal seams. Various conceptual designs are evaluated, including dual-depth boreholes for enhanced separation of thermal flow. Initial feasibility assessments highlight opportunities to align this scheme with the university's phased heat network strategy, providing a living laboratory for geothermal research and renewable energy integration.
This presentation will share preliminary findings, insights into borehole site selection, and recommendations for future mine water energy storage schemes. The work contributes to a growing body of research on sustainable heat management in post-industrial landscapes, aligning with broader UK initiatives in Gateshead, Leeds and Edinburgh, as well as Glasgow with the established UKGEOS project.
How to cite: Chapman, S., van Hunen, J., Basden, A., and Gluyas, J.: Data Centre waste heat storage within abandoned flooded mine workings, EGU General Assembly 2025, Vienna, Austria, 27 Apr–2 May 2025, EGU25-9263, https://doi.org/10.5194/egusphere-egu25-9263, 2025.
Abandoned and flooded coal mines have a huge geothermal potential. By circulating mine water and extracting its heat, it can provide a renewable, low-carbon low-enthalpy heat source for domestic and industrial purposes. But capital costs from drilling into those mine workings are significant, and investigating the geothermal potential of a mine system prior to drilling are essential for the success of any mine water geothermal energy (MWGE) system. Numerical modelling provides a quick and low-cost methodology to assess the feasibility of a planned MWGE system, for example to determine optimal mine water abstraction and re-injection sites.
Past coal mining was typically done using two different mining techniques. 1) The room-and-pillar (also referred to as pillar-and-stall) method was used to mine coal through digging tunnels (galleries and roadways), leaving pillars of coal untouched to prevent collapse of the coal seam. 2) The long-wall mining technique used machines to extract the entire coal seam, and allowed collapse in a controlled manner, thereby creating a porous layer of rubble referred to as ‘goaf’. Often both techniques were used within a single mine system. These two techniques result in very different remnant mine geometries, and it is important to address these differences in any MWGE modelling attempt.
We have developed a computationally fast and flexible modelling tool GEMSToolbox to assess the feasibility of mine workings as MWGE system by combining numerical and (semi-)analytical methods. The tool accounts for both room-and-pillar and long-wall mining techniques. In this study, we investigate the geothermal effects of both techniques for mines that are entirely constructed through one technique only, and for mines that combine the two techniques. Both techniques suffer from significant uncertainties in the effective model parameters: e.g. mine galleries may have collapsed since the mine closure, while for goaf, the effective porosity and hydraulic transmissivity are poorly constrained. Furthermore, in mine systems where both techniques were applied, water preferentially flows through the galleries, which potentially makes heat extraction from the goaf areas less efficient. The results of this study are applied to a real-world mine block in the North East of England.
How to cite: van Hunen, J., Wang, Y., Mouli-Castillo, J., and Tu, J.: The impact of different mining techniques on the geothermal potential of abandoned coal mines, EGU General Assembly 2025, Vienna, Austria, 27 Apr–2 May 2025, EGU25-9279, https://doi.org/10.5194/egusphere-egu25-9279, 2025.
Mining activities occur on all inhabited continents, which is why many countries are faced with the question of how exhausted mines can be utilised sustainably. One promising option is their use as energy sources, with flooded structures acting as sub-surface heat exchangers. The large water volumes offer significant potential for heating and cooling. However, the exploitation of abandoned mine is associated with high costs due to preliminary investigations and drilling. In order to minimise the economic risk, a reliable forecast of the mine water temperature is essential to ensure long-term economic viability. As complex thermal-hydraulic simulations require specific expertise, they are difficult to access for many energy suppliers and mine operators. This underlines the need for user-friendly models that allow an initial assessment of the potential without in-depth knowledge of modelling.
Only a few reduced models for predicting mine water temperature exist in the literature. While analytical models impress with extremely short calculation times (Milliseconds for decades), they are not able to take seasonal storage effects into account. Reduced numerical models from the literature can consider these transient effects, but require significantly longer calculation times (Minutes for decades), especially for turbulent flow regimes. This is too time-consuming for a comprehensive parameter study. In order to combine the advantages of both approaches, a new model is required that takes seasonal storage effects into account and works in an acceptable computing time (< 1 minute for decades).
The newly developed model combines two coupled sub-models: The heat transfer in the rock is solved numerically using an implicit finite volume scheme, whereby an irregular grid enables an efficient calculation. The energy transport in the fluid is modelled using an analytical solution. The verification using a reference case shows a high accuracy of the model. At a constant reinjection temperature, the deviation of the outlet temperature after twenty years is 3 % compared to the benchmark (fully numerical axisymmetric CFD simulation). With cyclical heat loads, the maximum deviation occurs for the inlet temperature with 3,5 %. At the same time, the model is around 750 times faster than the benchmark calculations with a run time of 1 s for two decades.
In order to test the model with practical operating modes, it is compared with an existing CFD simulation of the north-west field of the mine in Ehrenfriedersdorf, Germany. The comparison focuses on the temperature development of the mine water at the outlet, assessing how well the model captures seasonal variations and contributes to optimizing operational decisions.
How to cite: Krause, W., Ebel, T., Oppelt, L., Wunderlich, T., Raithel, F., Grab, T., and Fieback, T.: A reduced numerical model for predicting temperature dynamics in flooded mine galleries under seasonal heat loads and storage conditions, EGU General Assembly 2025, Vienna, Austria, 27 Apr–2 May 2025, EGU25-15555, https://doi.org/10.5194/egusphere-egu25-15555, 2025.
The Jharia Coalfield (JCF), the magnificent pocket of coking coal in the southern part of the Dhanbad district of Jharkhand India, has always remained at the peak of attention for the technological challenges that occurred during the mining of coal. The JCF is also the most critically highlighted coalfield as it is the only known depository of prime coking coal in India which is infamous for its extensive coal fires ignited mainly due to its dynamic spontaneous combustion nature. Earlier studies reported significant anomalous temperature variations in the range of 160-200⁰C along subsurface cracks and vents; also the geothermal gradient is locally high in the basin to be around 40-45⁰C/km. The implementation of geothermal heat extraction technologies to utilise the wasted heat underneath would require a comprehensive understanding and estimation of the techno-economics of various operational and maintenance costs. The economic assessment for a 5 MW geothermal plant revealed an initial investment cost of 12.02 (MM$) and 8.05 (MM$) and NPV to vary between 27.08 (MM$) to 31.04 (MM$) respectively for the source temperature of 100⁰C and 150⁰C in the burning JCF basin.
How to cite: Dutta, A. J., Mishra, C., Chaturvedi, R., Konwar, D., and Kulkarni, S. D.: Techno-Economic Assessment of Geothermal Energy Resource in the Jharia Coal Field of India, EGU General Assembly 2025, Vienna, Austria, 27 Apr–2 May 2025, EGU25-17341, https://doi.org/10.5194/egusphere-egu25-17341, 2025.
As the global energy transition accelerates, innovative solutions such as Mine Water Heat Systems (MWHS) are emerging to address the dual challenges of energy storage and decarbonised heating and cooling. This study focuses on the development of a business model for a heat geobattery system, which utilises abandoned mine workings to store thermal energy for heating, cooling, and thermal storage services, leveraging waste heat from a data centre.
We identify the operational roles, services, and responsibilities of a Mine Water (MW) operator and assess their impact on the heat supply chain. The UK’s regulatory landscape for MWHS is also investigated, highlighting gaps, barriers, and opportunities for regulatory enablement.
Additionally, we aim to build a database of technical risks to quantify the costs of mitigation strategies. This involves identifying critical risks associated with MWHS, including technical failures, environmental impacts, and regulatory non-compliance. Potential liabilities, such as pump and heat exchanger failures, mine gas release, and groundwater disruption, are analysed alongside their consequences, including downtime, environmental harm, and financial penalties. Mitigation strategies, such as regular maintenance, water quality monitoring, emergency response plans, and compliance frameworks, are proposed, with their costs estimated. These measures ensure system reliability, environmental protection, and adherence to regulatory requirements, enabling safe and efficient MWHS operations.
This study underpins the development of an investor-ready business model for the commercialisation of a heat geobattery system. Emphasis is placed on aligning financial incentives with operational feasibility, customer demand, and supply structure. By integrating these findings with the rest of the Galleries2Calories project, this research provides a framework for the seamless adoption of heat geobatteries. The outcomes contribute to understanding how MW operators can enhance the heat supply chain while addressing critical regulatory and environmental considerations.
How to cite: Mouli-Castillo, J., Watson, S., Nandagavi, P., Breunig, H., Swan, L., Smith, S., and Townsend, D.: Towards Investor-Ready Business Models for Mine Water Heat Systems: Regulatory, Technical, and Operational Insights for the Heat Geobattery, EGU General Assembly 2025, Vienna, Austria, 27 Apr–2 May 2025, EGU25-17354, https://doi.org/10.5194/egusphere-egu25-17354, 2025.
Underground mines, once vital industrial hubs, hold immense potential for innovative applications, including Mine Thermal Energy Storage (MTES). MTES repurposes partially and fully flooded mine cavities as reservoirs for storing surplus heat or cold, presenting a novel alternative to conventional Aquifer Thermal Energy Storage (ATES). While promising, MTES faces challenges such as scaling, corrosion, energy loss, and interactions between the geological matrix and technical infrastructure.
To address these challenges, TU Bergakademie Freiberg has established a living MTES geo-lab at the historic Reiche Zeche silver mine. Key features of this facility include a 21-cubic-meter water reservoir and over 90 temperature sensors embedded in Freiberg Gneiss. The pilot-scale MTES simulator setup allows for continuously monitoring heat transfer during thermal energy injection and extraction cycles realized by a mobile heat pump system. Early findings are revealing an average background rock temperature of 12 °C, a fast conductive heat transport within the rock as well as a good storage potential with elevated rock temperatures of up to 25 °C in approximately 2 meters from the water body. However, significant heat losses across system boundaries have been observed, with advective heat transport via flowing water identified as the primary contributor.
Parallel laboratory-scale experiments using column flow setups and batch reactors simulate MTES conditions, exposing rock and mine water to temperature cycles ranging from 10°C to 60°C. These experiments demonstrate significant chemical changes, including the precipitation of 90% of dissolved iron. These findings offer valuable insights into the chemical stability and thermal efficiency of MTES systems.
Two complementary methods were employed to quantify effective inflow and energy dissipation caused by mine water movement. First, a dilution test with NaCl was conducted. Second, inflowing water volume was calculated based on reservoir water level reductions. Results indicate that the calculation based on inflowing water volume provided more reliable values, while the formula used in the dilution test requires further refinement.
Additionally, numerical simulations using OpenGeoSys (OGS) software are being developed to assess the influence of fracture networks in the surrounding rock formation on heat storage and recovery performance. Preliminary results indicate that fractures enhance advective heat transport, leading to lower heat recovery ratios during cyclic operation.
How to cite: Arab, A., Binder, M., Oppelt, L., Chen, C., Wiedener, R., Schenker, F., Engelmann, C., Späker, C., Lotter, T., and Scheytt, T.: Storing Thermal Energy in Underground Mines: In Situ Simulations at the Freiberg Living Geo-Lab, EGU General Assembly 2025, Vienna, Austria, 27 Apr–2 May 2025, EGU25-19064, https://doi.org/10.5194/egusphere-egu25-19064, 2025.
Developing geothermal energy utilization technology is critical for achieving a low-carbon, high-efficiency energy system, and carbon neutrality objectives. The deep borehole heat exchanger (DBHE) represents a viable solution for extracting geothermal energy to meet building heating needs, especially in coal mines or oil fields with abundant depleted deep boreholes. In this study, a more comprehensive three-dimensional numerical model was constructed, incorporating segmented design parameters of the DBHE's inner pipe. The model's validity was confirmed through comparison with field experiment monitoring data. Subsequently, a series of long-term simulations were conducted to assess heat extraction performance, elucidating the influence mechanisms and interactive effects of various inner pipe parameters.
Additionally, a thermal-economic analysis was performed from a system-level perspective to quantify and evaluate the impact of inner pipe parameters on the DBHE's heat extraction performance, including assessing the necessity of inner pipe insulation. Results indicate that, under the specified conditions, reducing the thermal conductivity of the inner pipe increases the outlet water temperature while extending the payback period. Furthermore, greater drilling depth and lower circulation flow rate enhance the effectiveness of inner pipe insulation in improving the DBHE's heat extraction capacity, whereas the diameter of the inner pipe exerts a limited effect. These findings provide valuable guidance for the system design of practical DBHE heating projects in areas with depleted deep boreholes, enabling informed selection of inner pipe parameters.
How to cite: Cai, W., Xia, Q., Wang, F., Chen, C., and Meng, B.: Techno-economic performance analysis of deep borehole heat exchanger heating system towards transforming depleted deep boreholes, EGU General Assembly 2025, Vienna, Austria, 27 Apr–2 May 2025, EGU25-20061, https://doi.org/10.5194/egusphere-egu25-20061, 2025.
Posters on site: Thu, 1 May, 16:15–18:00 | Hall X4
Coal is a natural porous medium with a strong adsorption property and is an important energy resource over the world. The strong adsorption property of coal is a causative factor affecting the occurrence of coal and gas outburst. Gas is recognized as the main contributor to the energy release during outburst, and it initiates and maintains the chain process of outburst. Outburst is initiated by the fragmentation and failure of coal, where the adsorption property of coal plays a positive role. Additionally, the pore structure of coal is one of the significant factors affecting the CO2 sequestration performance. As a widely accepted potential management method for greenhouse gas, CO2 sequestration in coal seam is affected by the coal-mass properties, seam permeability, and long-term behavior of the sequestrated CO2. CO2 adsorption can significantly alter the porous property of coal and affect the CO2 sequestration capability of coal seams. Both outburst and CO2 sequestration are subjected to and significantly affected by a long-term sorption process. The former is promoted by the fragmentation of the coal mass induced by adsorption, whereas the latter is threatened by the adsorption-induced fracture. To explore the influence of long-term sorption on the mechanical and porous characteristics of coal, long-term sorption tests were performed. The results indicated that the long-term sorption significantly degraded the mechanical and microporous properties of coal. And, long-term CO2 adsorption even destroys and pulverizes the coal samples. The findings enhance our understanding of the mechanism underlying the fragmentation of the coal mass during outburst, while may present challenges for CO2 sequestration in coal seam.
How to cite: Zheng, J. and Chen, L.: Study on Mechanical and Microporous Properties Degradation of Coal with Long-Term Adsorption and Its Effect on Coal and Gas Outburst and CO2 Sequestration, EGU General Assembly 2025, Vienna, Austria, 27 Apr–2 May 2025, EGU25-5098, https://doi.org/10.5194/egusphere-egu25-5098, 2025.
The spatial distribution, scale, and structural properties of organic and inorganic pore-fracture networks are critical to evaluating shale petrophysical properties. This study conducted a quantitative analysis of the Shahejie Formation shale in the Dongying Sag based on field emission scanning electron microscopy (FE-SEM), revealing the organic-inorganic pore-fracture network characteristics, fractal characteristics and geological controlling factors of low-maturity shale. , and the influence of magnification on the observation results of pore structure was discussed. Results show that shale develops three types of pores: nanometer-sized intragranular pores (such as intercrystalline pores of clay minerals, calcareous mineral dissolution pores, and pyrite intercrystalline pores), and nanometer- to micron-sized intergranular pores (such as brittle minerals). intergranular pores and shrinkage fractures in organic matter) and micron-to-millimeter-scale fractures (such as feldspar fractures and organic-inorganic interface pores/fractures). Among these pores, inorganic pores account for 91.45% of the total pores and contribute 85.1% of the porosity; organic pores account for 8.54% and contribute 14.9% of the porosity; the surface porosity provided by organic pores is 2.2~2.6 times that of inorganic minerals. Among inorganic mineral pores, quartz and clay pores contribute about 49.8% of the storage space, followed by calcite (23.7%). Fractal analysis shows that inorganic pores have higher structural complexity, while organic pores dominated by organic-inorganic interface pores have lower fractal dimensions and relatively weak structural complexity and heterogeneity. The pore size distribution is unimodal, ranging from 10 nm to 4 μm, mainly concentrated in the 200 nm to 1 μm range. As the pore size increases, the contribution of pores of different scales to surface porosity gradually increases, with the micron-scale pore network accounting for 44.8% of the pore volume. The development of nanoscale pores is closely related to the proportion of clay mineral pores, and the degree of crack development is jointly controlled by the main diagenetic minerals (such as clay, quartz, and calcite). Magnification has a significant effect on surface porosity and pore complexity. At magnifications from 5000× to 20000×, the surface porosity of micropores (<200 nm) increased by 29.03 times, and the surface porosity of submicron pores (200-1000 nm) increased by 16.07 times. Fractal analysis further shows that the morphological complexity of inorganic pores is higher than that of organic pores. The number and surface porosity of mineral pores are closely related to mineral content. Pyrite has the largest porosity increment per unit area (2.19), while calcite has the smallest (0.732). These research results provide important data support for sustainable exploration of low-maturity shale and assessment of geological carbon sequestration potential.
How to cite: lin, Z., hu, Q., and Yin, N.: Organic and Inorganic Pore-Fracture Networks in Low-Maturity Lacustrine Shale: Insights from SEM Analysis in the Dongying Depression, EGU General Assembly 2025, Vienna, Austria, 27 Apr–2 May 2025, EGU25-5399, https://doi.org/10.5194/egusphere-egu25-5399, 2025.
The exploration of subsurface geothermal reservoirs has gained significant attention in recent years as a sustainable solution for energy storage and extraction. These reservoirs, ranging from shallow to deep geological conditions, offer immense potential to meet the growing demand for renewable energy while reducing reliance on fossil fuels. By leveraging the Earth's natural heat or over-seasonal waste heat, geothermal systems provide a reliable and environmentally friendly energy source for heating, cooling, and electricity generation. Recent advancements in technology and improved understanding of subsurface geological conditions have expanded the scope of geothermal applications, positioning them as a vital component of the global energy transition.
In this study, various geothermal systems in porous and fractured reservoirs are modeled using flow, heat, and mass transport processes implemented in the open-source software OpenGeoSys (OGS), such as Borehole Heat Exchangers (BHEs). The performance, sustainability, and efficiency of these geothermal systems are analyzed through scenarios involving inter-seasonal multi-cycles of energy use. Additionally, surface energy utilization systems designed for low- and mediate-grade geothermal heat sources, such as geothermal heat pumps and Organic Rankine Cycle (ORC) power plants, are modeled and optimized using the open-source simulation toolkit TESPy (Thermal Engineering Systems in Python).
This work also investigates the mechanisms of interaction between subsurface and surface facilities by coupling geothermal reservoir with thermodynamic process simulation. The integrated simulations enable further optimization of the entire system. This study aims to summarize progress made in modeling geothermal systems for energy extraction and storage using OGS, while also outlining future directions for developing large-scale integrated models that incorporate other renewable energy sources.
How to cite: Chen, C., Witte, F., Kolo, I., and Cai, W.: Modeling closed-loop and open-loop geothermal energy systems for the dual utilization of energy extraction and storage, EGU General Assembly 2025, Vienna, Austria, 27 Apr–2 May 2025, EGU25-8665, https://doi.org/10.5194/egusphere-egu25-8665, 2025.
As the world transitions to greener sources of energy, understanding how to best plan this transition becomes a critical challenge. A relatively recent approach contributing to the decarbonisation of heating and cooling infrastructure is repurposing abandoned mine networks to deploy geothermal energy technologies. These technologies utilise the subsurface to sustainably provide heating and cooling to buildings and are one of the key renewable technologies contributing to and shaping the decarbonisation of our energy landscape. Different configurations for exchanging heat with the ground can be used, such as closed- or open-loop systems, as well as operational strategies, such as utilising thermal storage, which can affect the subsurface requirements and design of the system.
With mining operations being increasingly shut down, geothermal mine systems not only constitute a sustainable method to providing heating and cooling energy, but also repurpose these abandoned sites and subsurface networks. Additionally, while geothermal energy technologies are generally highly efficient, important barriers to their wider implementation include relatively high capital costs due to subsurface-related uncertainties and the need for earthworks, as well as the dependency on groundwater flow conditions for certain applications. Integration with mines can contribute to overcoming these barriers, such as by minimising required earthworks, by reducing uncertainty through access to high quality data on the state of the subsurface, and by offering advantageous subsurface conditions for a geothermal system that takes advantage of the flow of water through the tunnels.
Integrating geothermal technologies within abandoned mine infrastructure to provide heating and cooling to buildings has been demonstrated and proven in several European countries in recent years. Large-scale projects, such as the Gateshead heat network in the UK (6MW heat pump) and the district heating system in Heerlen, Netherlands, showcase the potential of using flooded subsurface tunnel networks to provide geothermal energy at a large-scale. However, one potential smaller-scale application that has received little attention, and is the focus of this work, is utilising mining shafts.
Abandoned mining shafts are typically covered and flooded, making them a potential low hanging fruit for incorporating geothermal energy applications. While this concept is discussed in literature, more information is needed on the applicability and suitability of different geothermal configurations under different mine shaft conditions. This work contributes towards bridging this gap by utilising advanced finite element modelling methods to simulate a typical mine shaft, adopting a case study from the UK, and investigating in detail the potential energy yields of different geothermal applications under different conditions. Importantly, the effect of natural convection, expected to be significant in a flooded shaft compared to saturated soil, is carefully considered, acknowledging the complexities this introduces due to the difficulty of computational flow modelling at this scale.
How to cite: Makasis, N.: Exploring the use of mining shafts with geothermal systems using numerical modelling, EGU General Assembly 2025, Vienna, Austria, 27 Apr–2 May 2025, EGU25-17268, https://doi.org/10.5194/egusphere-egu25-17268, 2025.
The growing stringency of the European Union’s environmental policies, particularly in the area of atmospheric protection, has intensified efforts to mitigate greenhouse gas emissions across multiple sectors. Among the most concerning pollutants is methane (CH₄), well known for its high global warming potential. Recent regulations, including a methane ordinance, reinforce the necessity of reducing emissions from various sources, notably underground coal mines, where ventilation air methane (VAM) accounts for a significant fraction of overall greenhouse gas outputs.
Poland’s mining landscape presents unique challenges in harmonizing environmental objectives with economic imperatives. Of particular note is the strategic importance of coking coal, which the EU deems essential for steel production. In response, initiatives have emerged to uphold the necessity of steel-making while concurrently striving to meet stringent emissions reduction benchmarks. Within this context, the Central Mining Institute - National Research Institute in Poland (GIG) is spearheading research and development of cutting-edge solutions aimed at mitigating methane emissions from ventilation air streams. Central to these endeavors are thermal and catalytic oxidation methods, which offer a dual advantage: lowering methane levels and generating energy from the oxidation process. By converting VAM - even at relatively low CH₄ concentrations - into useful heat, these advanced technologies can significantly reduce overall greenhouse gas emissions. Concurrently, they provide opportunities for energy recovery, thus partially offsetting the operational costs associated with emission control. This model fosters greater economic viability while ensuring a more environmentally responsible approach to coal mining, critical for sustaining steel production across the EU.
How to cite: Hildebrandt, R. and Kruczek, M.: Emerging Technologies for Methane Emission Control and Energy Recovery in Underground Coal Mining, EGU General Assembly 2025, Vienna, Austria, 27 Apr–2 May 2025, EGU25-19602, https://doi.org/10.5194/egusphere-egu25-19602, 2025.
This study investigates unconventional resources such as coal and shale belonging to the Barakar Formation. Various analytical methods such as fluid invasive low-pressure gas adsorption (LPGA) and mercury intrusion porosimetry (MIP), small angle x-ray scattering (SAXS) and imaging methods were employed to determine the pore attributes and pore characteristics of coal and shale. The results show that coal has an abundance of nanopores that occurs in clusters, having evidence of microfractures in its structure, as observed through scanning electron microscopy (SEM). It was found that the accessible micropore surface area (SA) of coal samples is approximately 2.5 – 3 times that of shale samples, while the accessible and inaccessible mesopore SA in coal is about half of that in shale. Nevertheless, the average pore width of the coal samples is around 0.8 – 0.9 times that of the shale samples. These results suggest that the coal has a higher percentage of organic carbon that contributes to the abundance of organic pores, that leads to higher porosity in coal samples compared to shale samples. The total SA, incorporating the entire spectrum of pore sizes, is about 2 times as large in coal as in shale. Interestingly, despite disparity in pore SA and pore volume, the pore surface roughness in coal is nearly equal to or slightly higher than that of shale. The study provides a detailed analysis of the pore structures of unconventional resources, such as coal and shale from the same reservoir, considering various parameters such as depth, mineralogical content and surface roughness. During CO2 gas injection, the coal and shale formations may experience change in geomechanical responses, potentially compromising their mechanical stability. Furthermore, any loss to the caprock integrity could result in leakage and reservoir failure. Thus, this study is critical for estimating the secure CO2 storage capacity of coal and shale reservoirs. The findings aim to optimize gas adsorption while maintaining structural stability, ensuring the long-term feasibility of CO2 sequestration in other basins.
How to cite: Kumar, S., Chandra, D., Vishal, V., and Gamage, R. P.: Multiscale Pore Analysis of Unconventional Resources from the Barakar Formation using Fluid-Invasive, Scattering and Imaging Methods., EGU General Assembly 2025, Vienna, Austria, 27 Apr–2 May 2025, EGU25-977, https://doi.org/10.5194/egusphere-egu25-977, 2025.
In the transition from high CO2-emitting fuel to lower CO2-emitting fuel, natural gas hydrates (NGH) or methane hydrates (MH) provide an opportunity for further development. It is an ice-like solid trapping methane gas within its cage-like structure. It has a high energy density and a higher calorific value compared to coal, with 50% less CO2 emission. The availability of NGH globally is to such an extent that its 10% extraction can suffice the global energy demand for the next ~200 years.
However, NGH or MH reservoirs come with challenges such as extreme environments, difficult exploration conditions, unpredictable estimation of resources, etc. Though well-explored, the complex geological formations make them very difficult to produce from. The geological matrix of gas hydrates plays a crucial role in their dissociation, strength and mass transfer behaviour. The strength and fluid flow in the hydrate reservoirs is mainly governed by the impermeable layers of fine-grained sediments, which are mud/clay dominant.
To study the effect of interlayers on the strength of the MH sample, we conducted an experimental procedure that replicates the deep submarine environment. Unlike the conventional cylindrical core sample with homogeneous sediment distribution across the volume, the thin interlayers of fine-grain sediments (clay/mud) were introduced at different height intervals that mimicked the natural lithological conditions. The triaxial stress configurations replicate the real-world submarine environment where MH occurs. After applying confinement pressure, overburden pressure, and lowering the sample temperature to that of a hydrate-bearing zone, gas hydrates formed inside the sediment sample by injecting a mixture of methane and water. After the hydrate formation, the permeability of the sample was measured. Subsequently, the gas hydrate sample was allowed to dissociate, and the drained geomechanical test on the sample was performed. The depressurisation method was used for the dissociation of the hydrates.
During the experiment, P-S wave velocities were continuously measured. The wave velocities increased between pre and post-hydrate formation and decreased after dissociation. It indicates the enhancement in the strength of the sample due to hydrate formation and reduction due to dissociation. Furthermore, the sample showed compliance as the number of layers or layer thickness increased. The ductile behaviour was observed in the interlayered samples compared to those with non-layered (homogeneous). Moreover, peak strength was reduced by about ~15-20% in the dissociated samples compared with the hydrate-bearing sample. This study resolves the geomechanical behaviour of gas hydrate reservoirs, which is key to developing production strategies.
How to cite: Tulsawadekar, K., Vishal, V., and Gamage, R. P.: The effect of sediment interlayers on the triaxial compressive strength of gas hydrate-bearing sediments, EGU General Assembly 2025, Vienna, Austria, 27 Apr–2 May 2025, EGU25-1052, https://doi.org/10.5194/egusphere-egu25-1052, 2025.
Granitic terrains are increasingly utilized for underground disposal of radioactive waste from nuclear power plants, owing to their abundance and superior mechanical properties. However, the heat generated by radioactive waste can elevate burial site temperatures by up to 100°C, potentially compromising structural integrity through thermal expansion and fracture generation. The response of granites to elevated temperature depends on factors such as mineral composition, volatile mineral content, grain size, and pre-existing in situ stress conditions.
This study utilizes experimental techniques namely nanoindentation, micro-CT, SEM imaging, petrography, ultrasonic wave velocity measurements, XRD, and Thermogravimetric analysis to identify and evaluate the temperature dependence of the mechanical properties of two compositionally different granite samples. The initial composition and mechanical properties of the two granite samples were determined using the mentioned techniques. The samples were then subjected to a step-by-step heating protocol ranging from room temperature to 900°C. The properties of the samples were measured at regular intervals along the heating range and were analysed to find out the correlation with temperature.
Results revealed similar but distinct thermal responses between the two samples, with the most pronounced changes occurring between 500-600°C, coinciding with the α-β transition of quartz. Petrographic analysis, micro-CT, and SEM imaging demonstrated significant microcrack development at 600°C. Ultrasonic wave velocities showed progressive reduction with increasing temperature, indicating diminishing mechanical strength. Nanoindentation studies revealed that while the reduced modulus of all minerals decreased with heating, the rate of reduction varied among mineral phases. This comprehensive analysis demonstrates that elevated temperatures substantially reduce granite's strength and structural integrity, with the rate of degradation showing some dependence on compositional variations. These findings have important implications for the selection and engineering of underground radioactive waste disposal sites. Understanding the temperature-dependent behaviour of granite can help prevent potential leakage or environmental contamination, thereby addressing key safety concerns that currently limit broader adoption of nuclear technology.
How to cite: T Ashok, D. and Vishal, V.: Experimental Determination of Mechanical Property Evolution in Granites Subjected to Temperature Fluctuations: Implications for Safe Subsurface Disposal of Radioactive Waste, EGU General Assembly 2025, Vienna, Austria, 27 Apr–2 May 2025, EGU25-13059, https://doi.org/10.5194/egusphere-egu25-13059, 2025.
Posters virtual: Thu, 1 May, 14:00–15:45 | vPoster spot 4
EGU25-627 | ECS | Posters virtual | VPS17
Automated end-to-end fracture identification, classification, localization, and parameter estimation for enabling rapid risk management and CO₂ storage optimization in CCUS applicationsThu, 01 May, 14:00–15:45 (CEST) | vP4.4
The success of Carbon Capture, Utilization, and Storage (CCUS) projects heavily depends on understanding subsurface fluid flow behaviour particularly through fracture networks. Fractures play a dual role in such operations: they can enhance reservoir injectivity and storage capacity by providing pathways for CO₂ injection, but they also pose risks by potentially compromising caprock integrity, increasing the risk of structural storage failure thereby enabling CO₂ leakage. Accurate fracture detection and characterization is essential for optimizing injection strategies, ensuring effective containment, and mitigating environmental risks. Fractures influence critical processes such as trapping mechanisms and pressure distribution within the reservoir. Furthermore, understanding their orientation and density is vital for designing safe and efficient CO₂ injection operations. These factors highlight the importance of robust, non-bias, automated, and scalable fracture detection methods. Traditional fracture identification methods rely heavily on manual interpretation, which is time-intensive, subjective, and challenging to scale for large fields with several wells. This study proposes a scalable automated methodology employing advanced deep-learning techniques to detect fractures from borehole imaging tools such as FMI, CMI, and ThruBit logs. The proposed approach uses detection transformers which eliminates the need for manual mask creation and post-processing steps by adopting an end-to-end framework, which not only identifies the presence of fractures but also estimates their orientation and density. Custom evaluation metrics were developed to measure the model's performance (in comparison with expert’s fracture analysis) in handling diverse geological and well conditions, including vertical and horizontal well orientations. The automated workflow facilitates speedy assessment of fracture networks which in turn can offer speedy actionable insights for CO₂ injection optimization, caprock stability assessment, and risk management. The model demonstrated an interpretation speed of less than one minute per 2 meters, with an ~80% F1 score (6 cm depth error margin), ~91% accuracy in dip picking (3° error margin), and ~93% accuracy in dip estimation (15° dip margin). By utilizing the proposed automated fracture detection model based on transformers, CCUS project planning and designing can be accelerated. Furthermore, integrating MLOps into the workflow ensures the scalability, maintainability, and adaptability of these models for practical deployment. While this methodology is tailored to CCUS, its versatility extends to a much wider range of applications, including geothermal energy, mining, and other subsurface characterization domains.
How to cite: Nasim, M. Q., Maiti, T., Mosavat, N., Grech, P. V., Singh, T., and Roy, P. N. S.: Automated end-to-end fracture identification, classification, localization, and parameter estimation for enabling rapid risk management and CO₂ storage optimization in CCUS applications, EGU General Assembly 2025, Vienna, Austria, 27 Apr–2 May 2025, EGU25-627, https://doi.org/10.5194/egusphere-egu25-627, 2025.
EGU25-11945 | ECS | Posters virtual | VPS17
Organic compounds pose a risk for thermal storage in abandoned coal minesThu, 01 May, 14:00–15:45 (CEST) | vP4.5
The development of renewable energies and the sustainable utilisation of geo-resources is evident in the increasing interest in mine water utilisation. In the densely populated regions of former coal mining areas, flooded mine structures present a promising opportunity for seasonal heat storage called mine thermal energy storage MTES. In addition to the general risks associated with post-mining utilisation, it is essential to assess the potential hazards posed by contaminants that may be remobilised through this geotechnology. Hard coal naturally contains contaminants such as polycyclic aromatic hydrocarbons (PAHs) and NSO-heterocycles, which have been detected in mine water. The utilisation of coal mines as thermal energy storage facilities leads to significant heating of the mine water (up to 80°C), which can enhance the solubility and mobilisation of contaminants into the water. However, to date, no comprehensive understanding exists regarding the mobilisation potential of these contaminants from coal mines at varying temperatures.
In this contribution, we present initial systematic flow-through experiments using columns filled with different coal types at various temperatures demonstrating that contaminant mobilisation, after an initial first flush, is primarily dominated by diffusion processes at the phase interface. Differences in the mobilisation of PAHs between the various coal types and at various temperatures are discussed.
Using numerical simulations, we demonstrate that the compound concentrations grow exponentially over the runtime of the MTES system due to the growing mass of coal being thermally stimulated. High temperature storage can lead to a short production time until the regulatory limit for PAH is reached. Without regulatory action an MTES in coal mines might not be economically. We highlight that depending on mine-specific factors countermeasures need to be installed to contain the potential risk to the economic feasibility of such a storage system. A reduction of the pollutants trough remediation techniques might be possible to enhance the lifetime of the MTES system, if natural attenuation through micro-biological activity is not sufficient.
How to cite: Blaes, L., Licha, T., and Heinze, T.: Organic compounds pose a risk for thermal storage in abandoned coal mines, EGU General Assembly 2025, Vienna, Austria, 27 Apr–2 May 2025, EGU25-11945, https://doi.org/10.5194/egusphere-egu25-11945, 2025.
EGU25-1094 | ECS | Posters virtual | VPS17
Tree density, distribution and regeneration status in relation to soil quality at different alpine treeline regions of North-west HimalayaThu, 01 May, 14:00–15:45 (CEST) | vP4.6
The Himalayan alpine treeline possesses a unique identity and plays a vital role in the ecosystem. This study explores the relationship between soil quality and the distribution, diversity, and regeneration patterns of tree species in the alpine treeline regions of Uttarakhand Himalaya. The research focuses on five different treeline sites in Uttarakhand: Dayara Bugyal, Tungnath, Valley of Flowers, Ali-Bedni Bugyal, and Khaliya Top. Tree diversity and regeneration sampling in the treeline region were conducted by laying out 0.01 hectares quadrats, which were selected using the belt transect method along the treeline and soil samples were collected from each quadrate at 0-15 and 15-30 cm soil depths. The Rhododendron campanulatum, Quercus semecarpifolia, Abies spectabilis and Betula utilis are predominant in the treeline region of Uttarakhand Himalaya. Analysis of tree regeneration indicates generally poor regeneration for most species, with specific site variations. The additive Soil Quality Index (SQI) ranged from 2.30 to 2.84, 2.35 to 2.84, and 2.32 to 2.84 at soil depths of 0–15 cm, 15–30 cm, and 0–30 cm, respectively. Similarly, the weighted SQI showed a comparable trend, with Ali-Bedni Bugyal recording the highest values (0.95–0.96 across all depths). The reported SQI values exhibited a positive correlation with soil physicochemical properties and a negative correlation with vegetation density at the seedling, sapling, and tree stages. The site-specific variations in tree species distribution, diversity, and soil quality reflect distinct ecological dynamics and species interactions, while the poor regeneration status of most tree species highlights the need for targeted conservation strategies.
How to cite: Kumar, S., Sati, S. P., and Khanduri, V. P.: Tree density, distribution and regeneration status in relation to soil quality at different alpine treeline regions of North-west Himalaya, EGU General Assembly 2025, Vienna, Austria, 27 Apr–2 May 2025, EGU25-1094, https://doi.org/10.5194/egusphere-egu25-1094, 2025.
