Underground Hydrogen Storage Research Articles

Technology Focus: Mature Fields and Well Revitalization (January 2024)

In the relentless pursuit of a sustainable energy future, the often-overlooked potential of mature oil fields emerges as a beacon of hope. Once considered as being on the brink of abandonment, aging reservoirs are proving to be valuable assets as innovative hydrocarbon recovery techniques and re-envisioning of these fields for decarbonization opportunities are transforming them into reservoirs of opportunity. The sheer scale of mature oil fields globally is staggering. Advanced technologies and techniques, championed by internal initiatives that maximize the use of available data, are breathing new life into these reservoirs. While renewable energy sources are gaining traction, the world still relies heavily on hydrocarbons for its energy needs. One of the key advantages of reusing mature oil fields is the reduction in the need for new exploration and drilling. Exploring and developing new fields can be costly both financially and environmentally. By maximizing the recovery from existing fields, the industry can significantly decrease its ecological footprint and capitalize on the infrastructure already in place. Furthermore, the economic benefits of repurposing mature oil fields are substantial. The highlighted advancements focus on storage of various gases such as hydrogen, CO2, and natural gas, capitalizing on the knowledge gained from producing these fields for decades. Mature fields provide a bridge between the present and the future, offering a pragmatic solution to meet energy demands while mitigating environmental impact. Recommended additional reading at OnePetro: www.onepetro.org. SPE 214437 Fluid Modeling of Underground Hydrogen Storage in a Depleted Natural Gas Field by Markus Hays Nielsen, Whitson, et al. IPTC 22786 Particulate Wellbore Fluid-Strengthening Methodology—Design and Application in an Offshore Vietnam Severely Depleted Sand Reservoir by Dourado Motta Marcelo, SLB, et al. SPE 213405 Characterizing Movable and Nonmovable Zones in a Mature Carbonate Reservoir: A Novel Work Flow Using Resistivity Logs by Saud Al-Otaibi, Saudi Arabian Chevron, et al. SPE 214410 A Comparative Study of Hydrogen/Natural Gas Storage in a Depleted Gas Field in the Netherlands Using Analytical and Numerical Modeling by S. Hamidreza Yousefi, TNO, et al.

Storage of hydrogen with methane in underground reservoirs: forecast of associated processes

Based on the generalization of world experience in the underground storage of hydrogen with methane and the experimental work performed, the authors predict the development of hydrochemical, microbiological, geomechanical processes and phenomena that, in a real geological environment, will most likely accompany the joint storage of hydrogen and methane in underground formations. The issues of gas diffusion through the tire and hydrogen losses due to its consumption by microorganisms are also considered. Theoretical solutions are illustrated by calculations on synthetic models. Keywords: underground gas storage; hydrogen; methane; anaerobic microorganisms.

On the applicability of carbon steels K55 and L80 for underground hydrogen storage

To evaluate the possibility of hydrogen storage in depleted gas reservoirs, natural gas storage facilities, aquifers and salt caverns, the applicability of ferritic pearlitic K55 and tempered martensitic L80, both very frequently used as casings and tubings, has been investigated. Materials were investigated by means of high-pressure, high-temperature autoclave tests and analyses of the hydrogen uptake. The autoclave tests were performed on tensile specimens loaded with a spring at 90 % of the specified minimum yield strength, additionally the samples were analysed to determine the hydrogen uptake. Different gas compositions were considered (pure hydrogen, with or without the presence of CO2/H2S) under a hydrogen partial pressure of 120 bar. The tests were conducted in dry or wet environments. From the results, it can be seen that the hydrogen uptake is low even under the most severe conditions. However, from the mechanical test conducted in this study, it appears that the ferritic pearlitic K55 steel seems to be a suitable pipe material for underground hydrogen storage, and the higher strength steel L80 steel can be used only in non-sour environments (no significant amount of H2S in the reservoir, which is a priori the case of underground storages).

Molecular simulation on H2 adsorption in nanopores and effects of cushion gas: Implications for underground hydrogen storage in shale reservoirs

Hydrogen (H2), a renewable and clean energy source, plays an important role in the implementation of a low-carbon economy; however, hydrogen storage is challenging. Underground hydrogen storage (UHS) in shale reservoirs is a potential option for large-scale and long-term storage of H2. In this work, we used Grand Canonical Monte Carlo (GCMC) simulations to investigate the adsorption of pure H2 and H2 mixtures with CH4 or CO2 in kerogen and montmorillonite (MMT) nanopores under storage conditions. We found that pure H2 is more strongly adsorbed on kerogen, resulting in higher excess adsorption and consequently larger storage capacities. In the presence of CH4, H2 adsorption on kerogen is gradually weakened, indicating a stronger affinity between CH4 and kerogen surfaces. In contrast, co-adsorption of H2 and CH4 occurred on MMT surfaces. Moreover, H2 was almost completely desorbed by CO2, resulting in higher CO2 adsorption and selectivity (compared to CH4). Consequently, CH4 or CO2 can be used as the cushion gas as it greatly reduces the surface adsorption of H2, which is favorable for the retrieval of H2. Due to the stronger competitive adsorption ability, CO2 might perform better than CH4 in producing higher-purity H2. However, the presence of cushion gas significantly reduces H2 storage capacity, especially in smaller pores (<2 nm). This study provides important insights into H2 adsorption mechanisms and cushion gas effects in depleted shale reservoirs, thus helping to implement an industrial-scale hydrogen economy.

Computerized tomography analysis of potential geochemical reactions of carbonate rocks during underground hydrogen storage

The research on Hydrogen (H2) gas has attracted considerable attention as a clean energy source to achieve net-zero carbon emissions. Underground Hydrogen Storage (UHS) in carbonate reservoirs is a suitable solution for safe storage and efficient recovery of hydrogen during the cycling process. However, the potential geochemical reactions between hydrogen and carbonate minerals can influence the storage potential and rock characteristics. Despite the current devotion to evaluating H2-rock interactions, there is a lack of knowledge on the reactivity of carbonate rocks to hydrogen and the potential implications on pore properties. In this work, carbonate rocks were subjected to hydrogen treatment at 75 °C and 1400 psi for 150 days, and a comprehensive Computerized Tomography (μ-CT) scan analysis was performed. The results confirm the occurrence of geochemical reactions of dolomite and calcite with H2, however, the extent of mineral alteration is minimal, and the dissolution/precipitation rates are nearly balanced. Subsequently, insignificant changes in porosity (not exceeding 2 %) and grain expansion are observed. However, we observed unexpected development of fractures within 75–150 days of treatment in the calcite sample, which we believe is related to the de-pressurizing of the samples after 75 days of treatment, and not because of hydrogen reactions. The obtained results demonstrate the high stability of carbonate rocks during short hydrogen storage cycles and imply that the reaction of the carbonate minerals with H2 is very weak within the conditions investigated in this research. This work supports the utilization of carbonate reservoirs for UHS and can be a suitable experimental framework to assist in evaluating the hydrogen reactivity to carbonate reservoirs.

Underground Hydrogen Storage in the Bunter Sandstone Formation in the North German Basin: Capacity Assessment and Geochemical Modeling

With planned hydrogen import terminals and production sites along the North and Baltic Seas, the German coast is likely to become the center of the hydrogen economy. Underground hydrogen storage in the sedimentary reservoirs of the region, particularly in the Bunter Sandstone Formation, could provide the required storage capacity for the future hydrogen economy due to its widespread occurrence and proven sealing system. Herein, the storage capacity is assessed using a probabilistic volume approach and possible reactions between the Bunter Sandstone and hydrogen based on geochemical simulations with PHREEQC are determined. This assessment gives an effective storage capacity of 0.84–4.14 PWh in the saline aquifers of the Bunter Sandstone, of which 0.52–2.57 PWh could be stored onshore. If production from currently operating fields are to cease, additional capacities of between 89.43 and 285.53 TWh could be found in its hydrocarbon fields. Mineralogical reactions are shown to be restricted to redox reactions, which do not affect the formation integrity of siliciclastic reservoirs. As a result, pore storage facilities in the Bunter Sandstone could provide an important storage option for the hydrogen economy, but will require further investigations in the lab and in the field.

Data-driven machine learning models for the prediction of hydrogen solubility in aqueous systems of varying salinity: Implications for underground hydrogen storage

Hydrogen is a clean and sustainable renewable energy source with significant potential for use in energy storage applications because of its high energy density. In particular, underground hydrogen storage via the dissolution of hydrogen gas in an aqueous solution has been identified as a promising strategy to address the difficulties associated with large-scale energy storage. However, this process requires the accurate prediction of the solubility of hydrogen in aqueous solutions, which is affected by a range of factors, including temperature, pressure, and the presence of solutes. The present study thus aimed to effectively predict the solubility of hydrogen in aqueous solutions that vary in their salinity by employing a machine learning approach. Four machine learning models were developed and tested: adaptive gradient boosting (Adaboost), gradient boosting, random forest, and extreme gradient boosting. The performance of each model was quantified in terms of their coefficient of determination (R2), root mean square error (RMSE), and mean absolute error (MAE). The Adaboost algorithm exhibited superior performance across all metrics, with an R2 of 0.994, MAE of 0.006, and RMSE of 0.018. A Williams plot detected only 18 outliers in the Adaboost predictions from a total of 255 data points. These results indicate that machine learning techniques have the potential to serve as a valuable tool in the prediction of hydrogen solubility in aqueous solutions for underground hydrogen storage, facilitating the development of smart, cost-effective, and safe hydrogen storage technologies.

Techno-economic analysis of underground hydrogen storage in Europe

Hydrogen storage is crucial to developing secure renewable energy systems to meet the European Union's 2050 carbon neutrality objectives. However, a knowledge gap exists concerning the site-specific performance and economic viability of utilizing underground gas storage (UGS) sites for hydrogen storage in Europe. We compile information on European UGS sites to assess potential hydrogen storage capacity and evaluate the associated current and future costs. The total hydrogen storage potential in Europe is 349 TWh of working gas energy (WGE), with site-specific capital costs ranging from $10 million to $1 billion. Porous media and salt caverns, boasting a minimum storage capacity of 0.5 TWh WGE, exhibit levelized costs of $1.5 and $0.8 per kilogram of hydrogen, respectively. It is estimated that future levelized costs associated with hydrogen storage can potentially decrease to as low as $0.4 per kilogram after three experience cycles. Leveraging these techno-economic considerations, we identify suitable storage sites.

Molecular dynamics simulation of hydrogen diffusion into brine: Implications for underground hydrogen storage

Underground hydrogen storage has been the subject of extensive research recently. Hydrogen diffusion coefficient into brine critically affects hydrogen loss. However, the available data pertain to hydrogen diffusivity in pure water or NaCl solutions, with rare interpretations of temperature and salinity effects. In this paper, molecular dynamics simulations at realistic conditions were conducted to calculate these coefficients in various brines, particularly those containing divalent salts. The results indicate lower diffusivities at higher salinities and lower temperatures, the value being 7.29 × 10−9 m2/s at 323 K, increasing to 10.2 × 10−9 m2/s at 353 K for 1 molal NaCl solution. The diffusion coefficient decreases up to 38 % as the salinity increases from 1 to 5 molal. Besides, hydrogen diffusivity in MgCl2 solution is up to 60 % smaller than in NaCl solutions at the same molality. Radial distribution functions and hydrogen bond analyses confirm the results. This research provides new data for estimating hydrogen loss in aquifers or water-saturated caprocks.

Time‐lapse applications of the Marchenko method on the Troll field

AbstractThe data‐driven Marchenko method is able to redatum wavefields to arbitrary locations in the subsurface, and can, therefore, be used to isolate zones of specific interest. This creates a new reflection response of the target zone without interference from over‐ or underburden reflectors. Consequently, the method is well suited to obtain a clear response of a subsurface reservoir, which can be advantageous in time‐lapse studies. The isolated responses of a baseline and monitor survey can be more effectively compared; hence, the retrieval of time‐lapse characteristics is improved. This research aims to apply Marchenko‐based isolation to a time‐lapse marine data set of the Troll field in Norway in order to acquire an unobstructed image of the primary reflections and retrieve small time‐lapse traveltime difference in the reservoir. It is found that the method not only isolates the primary reflections but can also estimate internal multiples outside the recording time. Both the primaries and the multiples can then be utilized to find time‐lapse traveltime differences. More accurate ways of time‐lapse monitoring will allow for a better understanding of dynamic processes in the subsurface, such as observing saturation and pressure changes in a reservoir or monitoring underground storage of hydrogen and CO2.

Empirical and Numerical Modelling of Gas–Gas Diffusion for Binary Hydrogen–Methane Systems at Underground Gas Storage Conditions

The physical process in which a substance moves from a location with a higher concentration to a location with a lower concentration is known as molecular diffusion. It plays a crucial role during the mixing process between different gases in porous media. Due to the petrophysical properties of the porous medium, the diffusion process occurs slower than in bulk, and the overall process is also affected by thermodynamic conditions. The complexity of measuring gas–gas diffusion in porous media at increased pressure and temperature resulted in significant gaps in data availability for modelling this process. Therefore, correlations for ambient conditions and simplified diffusivity models have been used for modelling purposes. In this study, correlations in dependency of petrophysical and thermodynamic properties were developed based on more than 30 measurements of the molecular diffusion of the binary system hydrogen–methane in gas storage rock samples at typical subsurface conditions. It allows reproducing the laboratory observations by evaluating the bulk diffusion coefficient and the tortuosity factor with relative errors of less than 50 % with minor exceptions, leading to a strong improvement compared to existing correlations. The developed correlation was implemented in the open-source simulator DuMux and the implementation was validated by reproducing the measurement results. The validated implementation in DuMux allows to model scenarios such as Underground Hydrogen Storage (UHS) on a field-scale and, as a result, can be used to estimate the temporary loss of hydrogen into the cushion gas and the purity of withdrawn gas due to the gas–gas mixing process.

Technical and Economic Viability of Underground Hydrogen Storage

Considering the mismatch between the renewable source availability and energy demand, energy storage is increasingly vital for achieving a net-zero future. The daily/seasonal disparities produce a surplus of energy at specific moments. The question is how can this “excess” energy be stored? One promising solution is hydrogen. Conventional hydrogen storage relies on manufactured vessels. However, scaling the technology requires larger volumes to satisfy peak demands, enhance the reliability of renewable energies, and increase hydrogen reserves for future technology and infrastructure development. The optimal solution may involve leveraging the large volumes of underground reservoirs, like salt caverns and aquifers, while minimizing the surface area usage and avoiding the manufacturing and safety issues inherent to traditional methods. There is a clear literature gap regarding the critical aspects of underground hydrogen storage (UHS) technology. Thus, a comprehensive review of the latest developments is needed to identify these gaps and guide further R&amp;D on the topic. This work provides a better understanding of the current situation of UHS and its future challenges. It reviews the literature published on UHS, evaluates the progress in the last decades, and discusses ongoing and carried-out projects, suggesting that the technology is technically and economically ready for today’s needs.

Molecular simulations of hydrogen adsorption on coal with different ranks: Implications for hydrogen geo-storage

Underground hydrogen storage is a promising solution for the safe and efficient storage of industrial-scale H2. In this study, the adsorption behaviors of H2 in coal with different ranks under various temperatures and pressures are investigated using molecular simulations. It is found that the H2 adsorption capacity is positively correlated with coal rank, which is mainly attributed to the combined effects of surface chemical property and pore structure. Moreover, the isosteric heat of adsorption of H2 increases with the reduction in pore size due to the overlap of potential energy. In addition, the absolute adsorption amount of H2 in moist coal generally decreases with the increase in moisture content because of the competitive adsorption between water and H2 and the spatial occupation of water clusters/bridges. As a result, the anthracite coal seam with abundant micropores and few hydrophilic groups is considered to have a high potential for H2 storage.

“Innovative high pressure/high temperature, multi-sensing bioreactors system for microbial risk assessment in underground hydrogen storage”

This study addresses the microbial risks associated with Underground Hydrogen Storage (UHS), a critical component in the transition towards renewable energy systems, by employing an innovative multi-reactor system (Bio-xplorer) to simulate UHS conditions in two Italian reservoirs. The microbiological risk assessment (MRA) of Reservoir A and B was evaluated by subjecting them to gas mixtures of 10 % H2 and 90 % CH4, and 99 % H2 and 1 % CO2, respectively.In Reservoir A, the stability of pressure and temperature, the negligible optical density, and lack of microbial metabolites suggested a low risk of microbial activation. Molecular analyses confirmed the absence of sulphate-reducing bacteria (SRB) and limited growth of hydrogenotrophic methanogens (HM). Similarly, in Reservoir B, the absence of SRB and limited occurrence of HM indicated a low microbiological risk. Overall, the present work supports the safe and efficient implementation of UHS, a promising mitigation technique for climate change, using an innovative tool for MRA.

A numerical investigation on the utilization of a depleted natural gas field for seasonal hydrogen storage: A case study for Değirmenköy gas field

The growing interest in hydrogen (H2) within the energy sector has necessitated the development of alternative storage systems for H2. Depleted natural gas reservoirs, currently utilized for large-scale natural gas storage, are also seen as a feasible choice for storing H2. This study presents the results of numerical simulations to assess the applicability of utilizing the Değirmenköy gas field for underground hydrogen storage. The Değirmenköy gas field is onshore and depleted in the Thrace region of Türkiye. Cyclic storage simulations were run in four distinct scenarios to assess the reservoir's injection and withdrawal capacities and the H2 ratio of the withdrawn gas from the reservoir. If the injection and withdrawal flow rates are 1.5 million Sm3/day (250.0 thousand Sm3/day/well), a constant flow rate can be achieved on almost all days of the injection and withdrawal periods, and annual average H2 injection and withdrawal capacities were estimated as 221.5 million Sm3 and 177.7 million Sm3, respectively. Besides, H2 ratio of the withdrawn gas increased as storage cycles repeated and average H2 ratio increased to 88% in the last cycle. On the other hand, in the simulations performed with constant bottom hole pressure (BHP), both injection and withdrawal flow rates are quite variable during injection and withdrawal periods and peak flow rates at the beginning of each period is higher during H2 storage as compared to natural gas. Nevertheless, in both cases the flow rate gradually diminished and eventually ceased before the related period ended. Hence, it can be inferred that conducting storage operations with a steady flow rate, as opposed to a constant BHP, is deemed more suitable for the field under investigation due to the stability of flow rate. As a result, depleted natural gas reservoirs are considered a suitable option for H2 storage in large-scale, especially for applications without the need to obtain pure H2, considering their storage, injection, and withdrawal capacities.

Molecular Simulation of H2 Loss by Dissolution in Caprock Water-Saturated Nanopores under the Nanoconfinement Effect for Underground Hydrogen Storage

Molecular Simulation of H₂ Loss by Dissolution in Caprock Water-Saturated Nanopores under the Nanoconfinement Effect for Underground Hydrogen Storage

Biogeochemical characterization of four depleted gas reservoirs for conversion into underground hydrogen storage.

Depleted gas reservoirs are a valuable option for underground hydrogen storage (UHS). However, different classes of microorganisms, which are capable of using free H2 as a reducing agent for their metabolism, inhabit deep underground formations and can potentially affect the storage. This study integrates metagenomics based on Illumina-NGS sequencing of bacterial and archaeal 16S rRNA and dsrB and mcrA functional genes to unveil the composition and the variability of indigenous microbial populations of four Italian depleted reservoirs. The obtained mcrA sequences allow us to implement the existing taxonomic database for mcrA gene sequences with newly classified sequences obtained from the Italian gas reservoirs. Moreover, the KEGG and COG predictive functional annotation was used to highlight the metabolic pathways potentially associated with hydrogenotrophic metabolisms. The analyses revealed the specificity of each reservoir microbial community, and taxonomic and functional data highlighted the presence of an enriched number of taxa, whose activity depends on both reservoir hydrochemical composition and nutrient availability, of potential relevance in the context of UHS. This study is the very first to address the profiling of the microbial population and allowed us to perform a preliminary assessment of UHS feasibility in Italy.

Evaluation of the Dynamic Stability of Underground Structures Assuming a Hydrogen Gas Explosion Disaster in a Shallow Underground Hydrogen Storage Facility

Amid the ongoing global warming crisis, there has been growing interest in hydrogen energy as an environmentally friendly energy source to achieve carbon neutrality. A stable and large-scale hydrogen storage infrastructure is essential to satisfy the increasing demand for hydrogen energy. Particularly for hydrogen refueling stations located in urban areas, technological solutions are required to ensure the stability of adjacent civil structures in the event of hydrogen storage tank explosions. In this study, a numerical analysis using equivalent trinitrotoluene (TNT) and Concrete Damage Plasticity (CDP) models was employed to analyze the dynamic behavior of the ground in response to hydrogen gas explosions in shallow underground hydrogen storage facilities and to assess the stability of nearby structures against explosion effects. According to the simulation results, it was possible to ensure the structural stability of nearby buildings and tunnel structures by maintaining a minimum separation distance. In the case of nearby building structures, a distance of at least 6 to 7 m is needed to be maintained from the underground hydrogen storage facility to prevent explosion damage from a hydrogen gas explosion. For nearby tunnel structures, a distance of at least 10 m is required to ensure structural stability.

Bioreaction coupled flow simulations: Impacts of methanogenesis on seasonal underground hydrogen storage

Assessing microbial risks is key to feasible hydrogen storage in geological formations. This work quantitatively analyses the impacts of bio-methanation on hydrogen storage performance. Fine-scale flow simulations, coupled with the bio-methanation reaction, are presented to analyse its impact on the storage performance. Based on the reported rates in literature, methanogenesis may slightly degrade the recovery performance of hydrogen but is considered minor compared with the issue of gas mixing. The impacts of methanogenesis on a time scale of months (330 days) becomes observable in the system configured here, when the methanation rate is above 1746 nano molality per hour. The assumed methanation rate is two times greater than the rate reported from the Olla filed. Validated scaling theory generalises findings for gravity-dominated scenarios. But viscous-dominated flows see complications from property variations due to pressure changes at high rates. This study provides definitions of “target properties” (e.g., acceptable methanogenesis rates) for screening hydrogen storage projects.

Multi-criteria site selection workflow for geological storage of hydrogen in depleted gas fields: A case for the UK

Underground hydrogen storage (UHS) plays a critical role in ensuring the stability and security of the future clean energy supply. However, the efficiency and reliability of UHS technology depend heavily on the careful and criteria-driven selection of suitable storage sites. This study presents a hybrid multi-criteria decision-making framework integrating the Analytical Hierarchy Process (AHP) and Preference Ranking Organisation Method for Enrichment of Evaluations (PROMETHEE) to identify and select the best hydrogen storage sites among depleted gas reservoirs in the UK. To achieve this, a new set of site selection criteria is proposed in light of the technical and economic aspects of UHS, including location, reservoir rock quality and tectonic characteristics, maximum achievable hydrogen well deliverability rate, working gas capacity, cushion gas volume requirement, distance to future potential hydrogen clusters, and access to intermittent renewable energy sources (RESs). The framework is implemented to rank 71 reservoirs based on their potential and suitability for UHS. Firstly, the reservoirs are thoroughly evaluated for each proposed criterion and then the AHP-PROMETHEE technique is employed to prioritise the criteria and rank the storage sites. The study reveals that the total calculated working gas capacity based on single-well plateau withdrawal rates is around 881 TWh across all evaluated reservoirs. The maximum well deliverability rates for hydrogen withdrawal are found to vary considerably among the sites; however, 22 % are estimated to have deliverability rates exceeding 100 sm3/d, and 63 % are located within a distance of 100 km from a major hydrogen cluster. Moreover, 70 % have access to nearby RESs developments, with an estimated cumulative RESs capacity of approximately 181 GW. The results highlight the efficacy of the proposed multi-criteria site selection framework. The top five highest-ranked sites for UHS based on the evaluated criteria are the Cygnus, Hamilton, Saltfleetby, Corvette, and Hatfield Moors gas fields. The insights provided by this study can contribute to informed decision-making, sustainable development, and the overall progress of future UHS projects within the UK and globally.