Session ERE3.1

[Programme]

ERE3.1 | Secure subsurface storage for future energy systems

Orals |

Tue, 14:00

Posters on site |

Tue, 16:15

Posters virtual

Tue, 16:15

Secure subsurface storage for future energy systems

Convener: Johannes MiocicECSECS | Co-conveners: Eike Marie Thaysen, Niklas Heinemann, Katriona Edlmann, Suzanne Hangx, Juan Alcalde

Orals

| Tue, 25 Apr, 14:00–15:45 (CEST)

Room -2.16

Posters on site

| Attendance Tue, 25 Apr, 16:15–18:00 (CEST)

Hall X4

Posters virtual

| Attendance Tue, 25 Apr, 16:15–18:00 (CEST)

vHall ERE

Orals: Tue, 25 Apr | Room -2.16

Chairpersons: Johannes Miocic, Eike Marie Thaysen, Niklas Heinemann

14:00–14:05

5-minute convener introduction

CO2 Storage

14:05–14:15

EGU23-12119

ECS

Virtual presentation

Multiple caprock layers offer confidence in permanent geologic CO2 storage at the gigatonne scale

Iman R. Kivi, Roman Y. Makhnenko, Curtis M. Oldenburg, Jonny Rutqvist, and Victor Vilarrasa

Widespread deployment of Geologic Carbon Storage (GCS) at the gigatonne scale is projected to play a vital role in reaching carbon neutrality and mitigating the climate crisis. One major concern with GCS scale-up is the ability of geologic formations to retain CO₂ deep underground, at least over several thousand years. Of particular importance to this issue is the sealing capacity of the ideally low-permeability, high-gas-entry pressure caprock(s). Existing simulation studies to address the long-term fate of the injected CO₂ could barely exceed multi-century time scales due to high computational costs. This work aims to provide an improved understanding of the extent to which the potentially leaked CO₂ from basin-wide GCS may rise through a multi-layered system of laterally uniform aquifers and shale caprocks over geological time scales (million years). To this end, we develop a one-dimensional CO₂ flow and transport model, which is arguably capable of capturing the dynamics of basin-scale upward CO₂ migration. We consider two sets of caprock properties: (1) low intrinsic permeability (10^-20 m²) and high capillary entry pressure (2.5 MPa), obtained from laboratory measurements on intact clay-rich shales, and (2) high permeability (10^-16 m²) and low entry pressure (0.1 MPa), representative of pervasively fractured shales at regional scales. On the one hand, we find that the free-phase CO₂ can hardly penetrate more than a few centimeters into the intact caprock directly overlying the storage reservoir. CO₂ leakage in this scenario is exclusively governed by molecular diffusion with an estimated migration rate of 1 meter over thousands of years. On the other hand, the high permeability and low entry pressure of fractured caprocks enable CO₂ to break through the whole primary caprock during the injection and through the secondary one(s) in the post-injection period. However, following the gradual CO₂ pressure decline, brine imbibition back into caprocks suppresses CO₂ leakage and the percolating path is cut by an overlying caprock. Once the pore fluid of upper aquifers becomes CO₂-saturated, secondary CO₂ accumulations form and may host a significant portion of the injected CO₂. The extreme leakage scenario, which allows for further CO₂ rise of nearly one hundred meters becomes eventually diffusion-dominated and hence relatively safe. Our model results suggest that the presence of multiple shaly caprock layers, even if pervasively fractured, provides secure CO₂ containment in the subsurface over millions of years.

Reference

Kivi, I. R., Makhnenko, R. Y., Oldenburg, C. M., Rutqvist, J., & Vilarrasa, V. (2022). Multi-layered systems for permanent geologic storage of CO2 at the gigatonne scale. Geophysical Research Letters, 49, e2022GL100443. https://doi.org/10.1029/2022GL100443

How to cite: Kivi, I. R., Makhnenko, R. Y., Oldenburg, C. M., Rutqvist, J., and Vilarrasa, V.: Multiple caprock layers offer confidence in permanent geologic CO2 storage at the gigatonne scale, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-12119, https://doi.org/10.5194/egusphere-egu23-12119, 2023.

14:15–14:25

EGU23-5973

On-site presentation

Assessing permanent CO2 storage volume in a buried volcano offshore West Iberia

Davide Gamboa and Ricardo Pereira

In-situ mineral carbonation is a process that occurs naturally, through the interaction of CO₂ rich fluids and minerals of mafic and ultramafic rocks, towards the formation of new stable carbonate materials. Formed spontaneously in peridotites and serpentinites (e.g., the Samail Ophiolite of Oman), the concept has been successfully replicated through industrial applications with mineral trapping demonstrated to occur on Icelandic basaltic lava flows within a period of 2 years.

A Late Cretaceous volcanic edifice located on central West Iberian Margin, offshore Portugal, is investigated as a conceptual site for in-situ mineral carbonation, and a study case for the application of this model on similar volcanic edifices on continental margins worldwide.

Using seismic reflection surveys, the volcano is revealed as a 2800 m high edifice, with an estimated total rock volume of 327 km³. Dredges collected from an exposed crest of the volcano revealed vesicular olivine-rich sub-alkaline basalts, infilled with naturally formed carbonate minerals. Analysis of the internal architecture of the edifice reveals outward dipping reflectors, with its magmatic features assigned to alternating successions of lava flows and explosive debris, that have grown progressively to form a composite volcano. Lava flows directly associated with the final stages of volcanic build-up, comprise dendritic and lobate lava flows (pahoehoe or submarine flows) blanketing the flank of the edifice. Accounting for the auspicious architecture, nature, and rock properties of the edifice, a deterministic volumetric model is used to estimate different scenarios of the amount of CO₂ that can be safely and permanently stored in the volcano. Combining comprehensive inputs from bulk rock volume, effective porosity, and sequestration ratios, our estimations indicates that on a base case, the volcanic edifice has the potential to capture nearly 1.2 Gt CO₂ into new stable mineral phases. On a high case scenario, this single edifice could permanently capture up to 8.6 Gt of CO₂. Considering that during the 2015-2018 period, the Portuguese energy sector emitted an average volume of about 48 Mt CO₂ eq per year, our estimates suggest that the volcanic reservoir is capable of storing an equivalent of 24 years of the country’s industrial emissions. Compared with oceanic magmatic sequences worldwide, buried volcanic edifices on continental margins materialise as notable locations for in-situ mineral carbonation.

This assessment provides timely insights on the overall process of in-situ mineral carbonation, on ancient buried volcanoes, to reveal critical geological controls that can lead this technique to be applied on a pilot phase and envisage further concepts at economic scale. Moreover, geohazards associated with the proximity to populated areas are significantly minimised. Ultimately, results suggest that volcanoes on passive continental margins can be considered for safe and permanent carbon storage, by accommodating 100’s of Gt of CO₂ from energy intensive industry sources and contribute to mitigate the impacts of anthropogenic carbon emissions.

This work was funded by the Portuguese Fundação para a Ciência e a Tecnologia (FCT) I.P./MCTES through national funds (PIDDAC) UIDB/04035/2020-GeoBioTec and UIDB/50019/2020-IDL. D. Gamboa thanks FCT funding for project MAGICLAND (PTDC/CTA-GEO/30381/2017).

How to cite: Gamboa, D. and Pereira, R.: Assessing permanent CO2 storage volume in a buried volcano offshore West Iberia, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-5973, https://doi.org/10.5194/egusphere-egu23-5973, 2023.

14:25–14:35

EGU23-6015

ECS

On-site presentation

Rare methanogenic Archaea can become active in natural high-CO2 subsurface environments upon changing environmental conditions

Zeyu Jia, Daniel Lipus, Oliver Burckhardt, Robert Bussert, Megan Sondermann, Alexander Bartholomaeus, Dirk Wagner, and Jens Kallmeyer

The Eger Rift (Czech Republic) is characterized by deep-seated volcanic activity, leading to high CO₂ fluxes up to 125 kg m^-2 d^-1 and frequent tectonic activity. With its subsurface being naturally CO₂-rich at least since the Mid-Pleistocene, the Eger Rift is a natural analogue of underground CO₂ storage sites that allows for studying long-term effects of high CO₂ concentrations on the mineralogy and microbiology of such systems. Frequent small earthquakes lead to abiotic production of H₂, providing energy to indigenous microbial communities. Investigating the microbial communities residing in such natural analogue sites provides crucial knowledge about the possible log-term consequences of anthropogenic underground CO₂ storage. To assess the metabolic potential of the CO₂-adapted microbial community and its reaction to transient availability of Hydrogen, we evaluated diversity as well as metabolic attributes of bacterial and archaeal communities surviving under high CO₂ conditions, and their changes after exposure to Hydrogen.

A 230 m long drill core was recovered as part of the International Continental Drilling Program’s (ICDP) Eger Rift Project. Drilling was carried out under contamination-controlled conditions to provide pristine samples for geomicrobiological analyses.

We used cell counts and qPCR to assess microbial abundance across sediment and rock samples and both Illumina and Nanopore DNA sequencing platforms to gain insights into community structure and metabolic potential. Enrichments were set up to evaluate the ability of the CO₂-adapted microbial communities to utilize Hydrogen. We further isolated and purified active methanogens for detailed insights into their metabolic capability.

Our investigation revealed a CO₂-adapted community with low biomass and a surprisingly diverse archaeal population. Methanogens are rare and account for less than 1% of the total microbial community in most drill core samples. However, enrichments revealed an active hydrogenotrophic methanogen population from a narrow depth interval (50-60 m), dominated by Methanobacterium and Methanosphaerula. The autotrophic sulfate reducer Desulfosporosinus, also thrives in the same depth interval. We isolated methanogen strains from the enrichments from the 50-60 m depth interval, whereas enrichments from other depths remained low in biomass and showed little or no methanogenesis.

The strong differences in methanogenic activity among the enrichment cultures emphasize sediment heterogeneity, strongly suggesting the need for a high-resolution sampling strategy to evaluate the long-term effects of CCS. Our study shows that distinct processes may happen only in very narrow depth intervals and only reveal themselves through incubation/cultivation experiments, thus highlighting the importance of cultivation-dependent investigation on exploring the metabolic potential of microbial communities in subsurface environments.

How to cite: Jia, Z., Lipus, D., Burckhardt, O., Bussert, R., Sondermann, M., Bartholomaeus, A., Wagner, D., and Kallmeyer, J.: Rare methanogenic Archaea can become active in natural high-CO2 subsurface environments upon changing environmental conditions, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-6015, https://doi.org/10.5194/egusphere-egu23-6015, 2023.

14:35–14:45

EGU23-11844

ECS

On-site presentation

Modelling gravitational convection and miscible flows in heterogeneous porous media with a semi-Eulerian-Lagrangian scheme: implications for deep carbon sequestration.

Sayan Sen and Scott Hansen

The non-linear interaction of supercritical CO2 with brine in confined saline aquifers is an important problem in geophysical fluid dynamics and understanding its mechanism is pivotal for the design of carbon-sequestration schemes. In principle, dissolution of CO2 into the ambient brine from a buoyant supercritical phase across the CO2-brine interphase causes the density of the mixed diffusive layer to increase, thereby triggering gravitational instability generating Rayleigh-Taylor like convection and increasing CO2 dissolution and uptake by the reservoir. These dynamics are nonlinear and must be studied numerically, with previous works commonly focusing on homogeneous domains and pure diffusion only and often assuming no background flow in the aquifer.

We discuss a large-scale numerical Monte Carlo study considering the three-way interaction of heterogeneous permeability and porosity field structure, background flow, and local-scale dispersion on CO2 uptake. For this purpose, we developed a novel combined Eulerian flow—Lagrangian transport code for simulating single-phase CO2-enriched brine movement in systems featuring a spatially varying density field controlled by dissolved CO2 concentration and a background pressure gradient. The usage of the Lagrangian approach uniquely allows us to quantify the effect of local-scale horizontal and longitudinal dispersion on the flow dynamics and capture relevant non-Fickian transport behaviors without the confounding effect of numerical dispersion and to maintain numerical stability under strongly advective conditions.

We present results characterizing the impact permeability-porosity structure, background flow, local dispersion on CO2 uptake and fingering dynamics. Quantifying these factors via appropriate dimensionless groups, we analyze their impact on onset time of convection, and on regime transition from gravitationally dominated convection to background flow dominated advection-macrodispersion regimes. The relationship between porosity-permeability structure and fingering dynamics is also outlined and quantified.

How to cite: Sen, S. and Hansen, S.: Modelling gravitational convection and miscible flows in heterogeneous porous media with a semi-Eulerian-Lagrangian scheme: implications for deep carbon sequestration., EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-11844, https://doi.org/10.5194/egusphere-egu23-11844, 2023.

14:45–14:55

EGU23-16180

On-site presentation

Assessing the potential for permanent carbon storage in volcano-sedimentary sequences offshore mid-Norway: initial results from IODP Expedition 396

John Millett, Sverre Planke, Christian Berndt, Carlos Alvarez Zarikian, Peter Betlem, Marija Rosenqvist, Ben Manton, David Jolley, Simona Pierdominici, Stefan Buenz, and Reidun Myklebust and the Expedition 396 Scientists

International Ocean Discovery Program (IODP) Expedition 396 drilled 21 holes at 10 sites spanning the mid-Norwegian volcanic rifted margin in 2021. Six sites recovered volcanic sequences with one objective of the cruise being to appraise the potential for permanent carbon storage within the offshore volcanic sequences.

This study presents a core-log-seismic and reservoir appraisal of the Kolga High Site U1566 which penetrated a c. 120 m Seaward Dipping Reflector (SDR) sequence beneath a thin Quaternary sediment cover below c. 2100 m water depth. Coring with high average recovery > 65 % through the volcanic sequence revealed a variably altered basaltic lava flow dominated sequence with inter-layered volcaniclastic and siliciclastic sediments, the latter containing granitic clasts eroded from the nearby high. The base of the volcanic sequence was recovered in the cores and marks a sharp transition from sub-aerial lava flows into deeply altered granite.

Shipboard petrophysical and wireline data for Site U1566 are analysed to characterize the SDR sequence and integrated with available seismic data. Whole-Round Multisensor Logger data were collected on cores for natural gamma radiation, bulk density, magnetic susceptibility, and P-wave velocity at 2.5 cm spacing. 588 P-wave caliper measurements along with 2219 point magnetic susceptibility measurements were made on the working-half sections. In addition, a total of 102 discrete samples were taken for moisture and density (MAD) analysis including 2 cm cubes and 34 additional minicore samples which were also tested for ambient permeabilities. Wireline data including gamma, density, P- and S-wave velocity, resistivity, magnetic susceptibility and image log data (micro-resistivity and acoustic) were collected over the main volcano-sedimentary sequence enabling a comprehensive appraisal of the penetrated volcanic sequence.

The volcanic sequence is characterized by vertically stacked compound to simple lava flows showing asymmetrical log profiles with individual flow lobes rarely exceeding c. 3 m in thickness. Primary vesicular porosity exceeds 40 % in fresh unaltered flow margins and decreases to < 10 % in flow interiors and where alteration and secondary mineralization are pervasive. Matrix permeability ranges from microdarcies within flow interiors up to several 10’s of millidarcies within flow margins and up to 100’s of millidarcies within sediment interbeds highlighting significant vertical heterogeneity linked to facies development through the studied sequence. The presence of alteration and fracturing within the studied sequence significantly alter reservoir properties and form key elements, along with facies scaling, that must be incorporated into reservoir appraisal. This pilot study reveals clear reservoir potential within both lava flows and inter-bedded sediments offshore mid-Norway.

How to cite: Millett, J., Planke, S., Berndt, C., Alvarez Zarikian, C., Betlem, P., Rosenqvist, M., Manton, B., Jolley, D., Pierdominici, S., Buenz, S., and Myklebust, R. and the Expedition 396 Scientists: Assessing the potential for permanent carbon storage in volcano-sedimentary sequences offshore mid-Norway: initial results from IODP Expedition 396, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-16180, https://doi.org/10.5194/egusphere-egu23-16180, 2023.

Hydrogen storage

14:55–15:05

EGU23-2282

ECS

On-site presentation

Hydrogen underground storage in a saline aquifer at the Ketzin site (Germany) – a numerical pre-feasibility assessment

Lea Döpp, Wolfgang Weinzierl, Cornelia Schmidt-Hattenberger, and Ingo Sass

For integrating green hydrogen to the future energy system, underground storage facilities are needed. So far, there is no underground hydrogen pore storage facility in Germany. However, there is a lot of experience in town gas, natural gas , and CO₂ underground storage which now can be used for hydrogen storage pre-feasibility assessments, explorations and operations.

In this approach the Ketzin anticline (Germany) is used for a pre-feasibility assessment for hydrogen underground storage in a saline aquifer by using experimental and measurement data from its time as a CO₂ test site during 2004 to 2017.

For this first feasibility assessment we focused on the influence of several reservoir parameters on hydrogen solubility and the production rate. Therefore, the influence of the brine´s salinity, capillary pressure, reservoir pressure and temperature of two potential storage formations at Ketzin site is analyzed.

The Stuttgart formation was already used as a CO₂ storage formation during the projects CO2SINK, CO2MAN, COMPLETE. Due to loss reduction by a optimal structural trapping the potential hydrogen injection and production well is located at the top of the anticline – about 1.5 km north to the former CO2 storage test site. Based on Fleury´s experimental data from 2013, including capillary pressure, six parameter setups are created to simulate six hydrogen production and injection cycles.

For the second storage formation, the Exter formation, less experimental and measurement data is available. Therefore, six scenarios were designed on the basis of literature values. The end members represent a low and a high hydrogen recovery scenario which combine the best and worsed possible parameter setup for this formation.

The results show that it is important to consider the regional conditions individually and to respond to the specifications of the site to minimize economic and safety risks in hydrogen underground storage.

How to cite: Döpp, L., Weinzierl, W., Schmidt-Hattenberger, C., and Sass, I.: Hydrogen underground storage in a saline aquifer at the Ketzin site (Germany) – a numerical pre-feasibility assessment, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-2282, https://doi.org/10.5194/egusphere-egu23-2282, 2023.

15:05–15:15

EGU23-4237

ECS

On-site presentation

Numerical Assessment of Hydrogen and Gas Mixture Storage in Salt Caverns

Richard Wallace and Zuansi Cai

With the UK recently doubling its hydrogen production goals to adjust to the market demand the necessity for storage is becoming realised [1]. There are several options for utility-scale storage including salt caverns, deep saline aquifers and depleted gas fields. Salt caverns hold the unique benefit over porous storage of being capable of numerous cycles due to the dynamics of gas withdrawal, making them indispensable in the hydrogen storage strategy of each country. This is exemplified in the UK where it is anticipated to range up to 56TWh. Unfortunately, these are not as readily available as porous storage and hence, competition between different energy storage types may cause problems.

Of the subsurface energy storage systems, natural gas has been in operation for decades and is an established technology with numerous papers investigating different aspects of its operation and development. However, with the ambition of phasing out fossil fuel energy sources compressed air energy storage (CAES) and hydrogen storage are considered in Salt Caverns. It is also understood that during the transitionary period a gas blend may be utilised for the heating, currently, the maximum this stands at is 80:20 %vol of CH₄ to H₂. In most instances (at least for the UK), these systems will compete for storage as offshore wind farms, gas reservoirs and the national transmission system (gas grid) align [2]. Due to the different thermodynamic properties of each gas, it is important to know the impact of cyclic loading of each system on both the gas temperature and how this translates to its surrounding rock.

To investigate this, an idealised model of the NK1 cavern at the Huntorf CAES facility is developed and a historical operational cycle is simulated. Methane, Hydrogen and a Gas blend (80:20 %vol of CH₄:H₂) will be simulated and compared to that of the compressed air energy storage in[3]. This is then furthered by creating a mass-balanced cycle based on the initial cycle and extended for one month to see how these variations develop. The significance of this is to provide insight for the decision-making in which energy storage facility is appropriate for the region as a result of the numerical modelling.

References

Hydrogen Strategy update to the market: July 2022, E.I.S. Department for Business, Editor. 2022: London, United Kingdom.
Wallace, R.L., Z.S. Cai, H.X. Zhang, K.N. Zhang, and C.B. Guo, Utility-scale subsurface hydrogen storage: UK perspectives and technology. International Journal of Hydrogen Energy, 2021. 46(49): p. 25137-25159.
Guo, C.B., L.H. Pan, K.N. Zhang, C.M. Oldenburg, C. Li, and Y. Li, Comparison of compressed air energy storage process in aquifers and caverns based on the Huntorf CAES plant. Applied Energy, 2016. 181: p. 342-356.

How to cite: Wallace, R. and Cai, Z.: Numerical Assessment of Hydrogen and Gas Mixture Storage in Salt Caverns, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-4237, https://doi.org/10.5194/egusphere-egu23-4237, 2023.

15:15–15:25

EGU23-9900

ECS

On-site presentation

Compressed Air Energy and Hydrogen Storage Potential in Salt Structures in the UK Sector of the Southern North Sea

Sjastri Hansen and Jürgen Adam

Decarbonisation of energy grids as part of the accelerating zero-carbon energy transition requires the massive deployment of renewable energy sources like wind and solar power. Because of their intermittent nature, grid-scale energy storage solutions are required on all scales ranging from battery storage, pumped-storage hydroelectric power and subsurface energy storage solutions.

Energy storage in geological formations, for example, depleted hydrocarbon reservoirs, saline aquifers and man-made rock and salt caverns, has been employed for decades and is ideal because of the potential to safely store large volumes of energy with negligible effects on the surface environment.

Man-made salt caverns have been in widespread use for natural gas storage. Salt formations are ideal due to the inert, impermeable and self-healing nature of salt. Gas can therefore safely be stored in large geometrical volumes at high storage pressures, making it optimal for not only natural gas storage but also electrical energy storage in the form of compressed air (CAES) or hydrogen (HES).

The study is in the Southern North Sea basin (SNS). The SNS is characterised by the accumulation of massive cyclical evaporitic sequences, which were extensively deformed by post-Permian salt movement of Zechstein salt sediments resulting in thicknesses ranging from less than 50m to greater than 2500m.

The North Sea oil and gas sector has been at the heart of the UK energy security. The SNS has undergone decades of extensive exploration yielding large volumes of geological and geophysical data available for renewable energy and energy storage research.

By means of 3D seismic reflection and well data interpretation, this work employs an established screening method used in the hydrocarbon industry, Play Fairway Analysis, to identify potential exploration targets on a regional scale. This approach involves determining the presence and efficiency of a source, migration pathway, a reservoir, a seal and assigning a risk factor to each based on those criteria.

The source and migration pathway equivalents are the location of current and future offshore infrastructure, the reservoir equivalent is defined by the characteristics and distribution of the salt structures and the seal equivalent is defined by the operational constraints within which energy storage can safely occur. The design and placement of salt caverns is governed by the characteristics of the salt deposit and the thickness of the salt layers above and below the cavern. The operational depth range required for sustainable and safe operation is between 400-1500m. The resultant common risk segment map highlights areas with highest energy storage potential.

Initial results indicate that numerous prospective salt structures in the UK sector of the SNS are readily located near existing and future planned offshore wind parks. Future work will build on this through geological characterisation of the target salt structures, shallow hazard assessment, geomechanical assessment to determine cavern placement and storage capacity. The key outcomes of this study include a regional overview of the number and distribution of salt structures, their respective storage potential and the overall feasibility of CAES and HES implementation as part of the UK energy transition strategy.

How to cite: Hansen, S. and Adam, J.: Compressed Air Energy and Hydrogen Storage Potential in Salt Structures in the UK Sector of the Southern North Sea, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-9900, https://doi.org/10.5194/egusphere-egu23-9900, 2023.

AETS

15:25–15:35

EGU23-16675

Highlight

On-site presentation

DemoStorage - an ATES demonstrator in an urban environment.

Detlev Rettenmaier, Roman Zorn, Philipp Blum, Menberg Kathrin, Matthias Herrmann, Michael Viernickel, Fabian Eichelbaum, Paul Fleuchhaus, Thorsten Stoeck, Sven Katzenmeier, Hans-Werner Breiner, Hans Jürgen Hahn, and Andreas Fuchs

Aquifer thermal energy storage (ATES) is comparatively rarely used in Germany, in contrast to neighboring countries such as the Netherlands. This also applies to lower temperature ranges of less than 50 °C, which are mostly technically easier to handle than high-temperature storage. Since there is a lack of demonstration plants nationally, the goal of our BMBF-funded joint project “DemoSpeicher” (Development and Monitoring of Seasonal Heat and Cold Storage for the Demonstration of Aquifer Storage) is to implement and scientifically accompany a near-surface low-temperature aquifer storage system (NT-ATES). Within the scope of the project, the entire construction cycle of an NT-ATES is to be covered, which ranges from design and planning to grid integration and commissioning to thermal energy supply. An urban site in Germanys capital Berlin-Mitte was selected for the implementation of the demonstration plant, which is to be converted to climate-friendly heating and cooling concepts at an existing construction site. In addition to the necessary preliminary site investigations for the technical-economic feasibility, questions regarding legal approval requirements will also be presented.

For this reason, a extensive monitoring program is planned, which provides the metrological supervision of the thermal-hydraulic underground processes. Another focus of the project will be possible changes in groundwater chemistry and temperature-sensitive groundwater ecology as a result of thermal loading. Monitoring of energy flows is also planned in order to estimate the thermal energy exchange between the aquifer reservoir and the building's systems engineering. This will include a heating and cooling demand analysis, as well as an assessment of potential synergistic use effects with other technologies that could be used, for example, for thermal loading of aquifer storage. All results will be presented in a coupled thermal-hydraulic modeling of the planned thermal energy storage. The project and the first results of the implementation of an ATES in a densely populated urban area will be presented and discussed in this presentation.

How to cite: Rettenmaier, D., Zorn, R., Blum, P., Kathrin, M., Herrmann, M., Viernickel, M., Eichelbaum, F., Fleuchhaus, P., Stoeck, T., Katzenmeier, S., Breiner, H.-W., Hahn, H. J., and Fuchs, A.: DemoStorage - an ATES demonstrator in an urban environment., EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-16675, https://doi.org/10.5194/egusphere-egu23-16675, 2023.

General storage

15:35–15:45

EGU23-17508

On-site presentation

Predicting the frequency of seismic events for subsurface engineering projects usingbackground microseismicity data

Eleni Dafnioti, Georgios Chatzopoulos, Stella Pytharouli, Filippos Vallianatos, and Rebecca Lunn

The general public is concerned about subsurface energy projects and their link to seismic activity.
However, in order to meet the Net Zero requirements, low carbon technologies involving fluid
injection into the subsurface, such as geothermal, Carbon Capture and Storage (CCS) and gas
storage, must be developed and implemented. In an effort to enhance their confidence, it is
important to comprehend the seismogenic effects and the triggering mechanism that such
technologies could have in a region.
The frequency of occurrence of microearthquakes (earthquakes with magnitude < ML0 in the
Gutenberg – Richter scale) in natural faults can provide crucial details about the evolution of
seismicity of a region and the geological structures that support this. The permanent seismic
monitoring networks, due to their detection threshold on small magnitude earthquakes (< ML1), do
not enable for the long – distance recording of all microearthquakes. These events have higher
frequencies that attenuate fast, making detection at stations 10s or more kilometres away difficult,
if not impossible.
In order to determine whether microearthquakes share the same characteristics as larger
earthquakes and whether they can be used as a precursor to the occurrence of larger earthquakes,
this research focuses on the study of the characteristics of natural microseismicity (frequency of
occurrence, magnitude distribution, depth of hypocentres etc.). In July 2022, we deployed a
temporary microseismic monitoring network in the southern Heraklion prefecture (Crete, Greece) in
collaboration with the Hellenic Seismological Network of Crete with the aim of recording very small
in magnitude earthquakes (within the range of -0.5 < M < 3, i.e. two orders of magnitude below the
current completeness magnitude of M c 2.0). The network consisted of seven short period
seismometers, one of which was placed in the centre of a nearly circular geometry with the
remaining six distributed around it at a radius of approximately 6.1km. This geometry provided a
good azimuthal coverage for determining the hypocentres.
In this work, we present analysis and results of the microseismic data collected from our local
monitoring network. We find a significantly larger number of microseismic events than that reported
for the same time period within 50 km distance from the central station of our local network in the
published seismic catalogue by the National Observatory of Athens. The number of detected events
we report here refers to only those events that can be visually observed in the recordings. The real
number of smaller in magnitude events is larger but obscured by noise. We use the detected
microseismic events to populate the Gutenberg Richter magnitude distribution for lower magnitude

events and discuss the implications on the existing Gutenberg Richter magnitude distribution for the
region as derived from events recorded by the permanent seismic network in Crete.

How to cite: Dafnioti, E., Chatzopoulos, G., Pytharouli, S., Vallianatos, F., and Lunn, R.: Predicting the frequency of seismic events for subsurface engineering projects usingbackground microseismicity data, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-17508, https://doi.org/10.5194/egusphere-egu23-17508, 2023.

Posters on site: Tue, 25 Apr, 16:15–18:00 | Hall X4

Chairpersons: Juan Alcalde, Katriona Edlmann, Johannes Miocic

CO2 Storage

X4.138

EGU23-4456

ECS

Well...Well...Well...: Using sparse data to do preliminary modeling and numerical simulations for subsurface storage in Western Nebraska

(withdrawn)

Samuel Fleagle, Cara Burberry, Seunghee Kim, and Lateef Lawal

X4.139

EGU23-13953

ECS

Storage Potentials for artificial CO2 products in Germany

Sarah Diekmeier, Karsten Reiter, and Colin Friebe

To achieve the EU's net zero emissions target in 2050, unconventional measures to remove CO₂ from the atmosphere are urgently needed (IPCC, 2016). Due to the very tight remaining CO₂ budget, all illustrative model pathways in the IPCC special report on the 1.5°C target assume that net negative emissions must be achieved in the second half of the century. Direct storage of pure carbon dioxide has been investigated and is still applied, but limited depending on the location by restrictive laws, geological availability, and the uncertain long-term safekeeping. The NETPEC project strives to use photo-electro-chemical methods as energy source to produce easily storable, safe and sustainable carbon-sink products. These solid or liquid carbon-rich products can be long-term stored in the underground or at the surface.

The aim of the project part, which will be presented, was to create a database containing the storage potentials of Germany with respect to different end products with a large as possible carbon content. Further criteria for the storage sites are a guaranteed safe deposit for at least 1000 years, no negative influence on the surrounding biosphere and its living organisms and no negative interactions between product and repository of any kind. Due to large volumes of production from opencast and mining operations, sites that appear to be suitable in Germany are former open-pit and underground mines. In the case of a fluid product, various underground storage facilities such as hydrocarbon fields and pore storage complexes appear suitable too. In addition, a disposal of solid end products via regular landfills is conceivable. The collected data were provided by the state offices of the federal states and included both legal office maps in raster format which were digitalized and supplemented by other provided or public data as well as shape files with attributes. Depending on the information provided by the states, the database contains the location, the name of the location, owner of the location, area of the location, type of authorization, type of natural resource and for some states also the extracted volumes of the resources.

Production quantities and volumes can be used to compare the capacities of potential storage sites with the volume of the CO₂ product. As an interim result, both the qualitative opportunities and the quantitative potentials for final repository of solid or liquid carbon-rich product near the surface or underground are shown and illustrate the clearly widely distributed, large potential of the extensive volumes for storage in Germany.

How to cite: Diekmeier, S., Reiter, K., and Friebe, C.: Storage Potentials for artificial CO2 products in Germany, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-13953, https://doi.org/10.5194/egusphere-egu23-13953, 2023.

X4.140

EGU23-16856

Highlight

Solid Carbon: Safe and Durable Carbon Storage in Ocean Basalt - From Feasibility to Demonstration to Global Potential

Benjamin Tutolo, Martin Scherwath, Kate Moran, David Goldberg, Adedapo Awolayo, Laurence Coogan, Curran Crawford, Stan Dosso, Eneanwan Ekpo Johnson, Rachel Lauer, Emma Louis, Sara Nawaz, Terre Satterfield, Angela Slagle, Devin Todd, and Romany Webb

Oceanic crustal basalt rock has been identified to be the most abundant CO2 sequestration reservoir on earth with a total capacity of up to 250,000 Gt of CO2 and the added advantage of the CO2 mineralizing into carbonate rock in the safest and most durable way. Experiments and pilot projects have established geologic carbon storage in basalt on land (e.g. Carbfix in Iceland) but have not been carried out offshore and are therefore required to demonstrate and prove this form of carbon storage offshore. We are presenting the ongoing Solid Carbon project, which is currently in the feasibility stage of demonstrating this concept in the Cascadia Basin offshore Vancouver Island where Ocean Networks Canada operates a cabled ocean observatory, which will be utilized to monitor and verify this form of geologic carbon storage. The demonstration site is at about 2700 m water depth, where the ocean crust is overlain by 200-600 m of sediment acting as a cap for the porous and permeable crustal basalt aquifer (300-500 m thick), underlain by a thick conductive basement. From previous seafloor drilling campaigns, the subsurface and hydrogeology in this area are well known, feeding both into sequestration modelling and also planning the required monitoring. In addition to planning the offshore demonstration experiment, the Solid Carbon project further includes research on social, regulatory and social acceptance as well as adding offshore energy and direct carbon capture to transform the concept into a negative emission technology. We will present the past, present and potential future of this form of geologic carbon storage.

How to cite: Tutolo, B., Scherwath, M., Moran, K., Goldberg, D., Awolayo, A., Coogan, L., Crawford, C., Dosso, S., Ekpo Johnson, E., Lauer, R., Louis, E., Nawaz, S., Satterfield, T., Slagle, A., Todd, D., and Webb, R.: Solid Carbon: Safe and Durable Carbon Storage in Ocean Basalt - From Feasibility to Demonstration to Global Potential, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-16856, https://doi.org/10.5194/egusphere-egu23-16856, 2023.

X4.141

EGU23-323

ECS

Monte Carlo modelling of a pulsed neutron capture tool for CO2 saturation estimation in sandstone reservoirs

Jozsef Gabor Szucs, Attila Galsa, and Laszlo Balazs

One of the key factors for a successful carbon capture and storage (CCS) project, is the ongoing monitoring of the carbon-dioxide injected into the reservoir rocks. Borehole geophysics measurements are invaluable for this process. Due to the evident presence of borehole casing, the number of effective well logging methods is limited. This means, that nuclear measurements play a highly important role owing to their relatively great depth of penetration. We present a method for PNC (Pulsed Neutron Capture) tools to estimate CO2 saturation in sandstone reservoirs independently of the water salinity. To achieve this, we utilize a carefully selected energy window in the inelastic part of the gamma spectra. The ratio created from the number of counts in this window for different detector spacings is sensitive to hydrogen content of the reservoir rock, thus indirectly to CO2 saturation as well. We estimate the energy deposited by gamma photons in the scintillation detectors of the PNC tool for different model parameters such as rock properties (e.g. porosity) and CO2 saturations. A systematic modelling of the measurement was carried out using Monte Carlo N-Particle (MCNP), a general-purpose particle transport code. These results demonstrate the potential of this method for CO2 monitoring in sandstone reservoirs.

How to cite: Szucs, J. G., Galsa, A., and Balazs, L.: Monte Carlo modelling of a pulsed neutron capture tool for CO2 saturation estimation in sandstone reservoirs, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-323, https://doi.org/10.5194/egusphere-egu23-323, 2023.

Hydrogen storage

X4.142

EGU23-10005

Highlight

(Pre)feasibility study of underground hydrogen storage potential in depleted gas fields and salt caverns in the Netherlands

Joaquim Juez-Larré, Cintia Gonçalves Machado, Hamid Yousefi, Ta-Kai Wang, Remco Groenenberg, and Serge Van Gessel

Hydrogen is expected to play an important role in our future energy system. It is a versatile energy carrier that can be produced from renewable electricity and then be used as a CO₂-neutral fuel for (re)generating electricity and/or heat, or as feedstock for the chemical industry. Hydrogen can be stored underground in large quantities and therefore has the potential to take over the role of natural gas in securing the supply of energy. Although depleted gas fields can potentially store larger volumes of hydrogen than current clusters of salt caverns, UHS in porous reservoirs is not yet a proven technology. To enable future demonstration/pilot projects, screening studies are needed for the identification and characterization of potential underground candidates.

Since 2012, the Dutch Ministry has funded several national (pre)feasibility studies to estimate the potential for underground natural gas and hydrogen storage (UGS & UHS) and flow performance of depleted natural gas fields and salt caverns clusters in the Netherlands. Various methodologies and criteria are being utilized. Analog methods provide first-order estimates on UHS capacities based on the volume of natural gas originally contained in fields and clusters of salt caverns. This reveals a total theoretical maximum storage capacity onshore of up to a few hundred TWh for fields and tens of TWh for clusters of salt caverns. More accurate estimates were obtained from nodal analyses using the analytical inflow performance relationship (IPR) and the vertical flow performance (VFP) curves. Surface limitations were considered for onshore areas such as groundwater, protected and urban areas, which shows a significant reduction, on average around 60%, in the total theoretical storage capacity. Because of that, and in order to search for alternative UHS sites, more attention has been paid to depleted fields and salt pillars in offshore areas. For this, realistic technical limitations were assumed, such as the working pressure range of transmission systems between 150 and 250 bar. This reveals a significant reduction in the storage capacity and flow performances, as many fields would not be filled to their maximum working capacity. For a better understanding of the difference between the performance of UGS and UHS, three UGSs currently in operation in the Netherlands were investigated in more detail. Results show that the range of working pressures at which they may operate significantly determines the amount of energy that a UHS can store. Results from ongoing numerical modelling (Eclipse 300) for some of the best depleted gas fields allow quantifying the efficiency of different operating strategies and the number of wells required based on injection/withdrawal cycles at various timescales (daily-weekly-monthly), distinct ranges of working pressures and types of cushion gas (e.g. nitrogen/hydrogen). Other aspects such as geochemical reactions, microbial activity and type of residual gas in the different fields are also being considered as selection criteria. These ongoing studies are expected to facilitate the screening and design of future demonstration/pilot projects for UHS in gas fields and salt caverns in the Netherlands beyond 2030.

How to cite: Juez-Larré, J., Gonçalves Machado, C., Yousefi, H., Wang, T.-K., Groenenberg, R., and Van Gessel, S.: (Pre)feasibility study of underground hydrogen storage potential in depleted gas fields and salt caverns in the Netherlands, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-10005, https://doi.org/10.5194/egusphere-egu23-10005, 2023.

X4.143

EGU23-1909

Microbial Risk Assessment for Underground Hydrogen Storage in Porous Rocks

Eike Marie Thaysen, Timothy Armitage, Lubica Slabon, Aliakbar Hassanpouryouzband, and Katriona Edlmann

Climate change, triggered by a continuously rising use of carbon based energy sources, is a global concern. Geological hydrogen storage, e.g. in depleted gas fields or saline aquifers, can overcome imbalances between supply and demand in the renewable energy sector and facilitate the transition to a low carbon emissions society, in this way mitigating climate change. However, a range of subsurface microorganisms utilise hydrogen which may have important implications for hydrogen recovery, clogging and corrosion. We created a novel, globally applicable risk categorization tool based on the published environmental growth constraints of all major hydrogen utilizing microbes (hydrogenotrophic methanogens, hydrogenotrophic sulphate reducing bacteria, homoacetogens and hydrogenotrophic dissimilative iron reducing bacteria) and on reports of paleosterile subsurface environments. Application of the tool to 75 depleted or close to depleted gas fields on the UK continental shelf showed that 9 fields fall either within the ´No Risk´ category with temperatures >122 °C, making them the ideal candidates for hydrogen storage from a microbial risk point of view. Hydrogen storage in the 35 ´Low Risk´ fields with temperatures >90 °C or the 22 ´Medium Risk´ fields with temperatures >55 °C and salinities >1.7 M NaCl will require the careful characterization of the microbial community composition to assure that hydrogenotrophic microorganisms are not present. We recommend against utilising depleted gas fields with temperatures <55 °C which are at high risk for adverse microbial effects.

Results were mapped and aligned with centres for renewable energy production and out-of-use pipelines suitable for repurposing to transport hydrogen. This showed that No Risk or Low Risk depleted gas fields in the Southern North Sea are the most suitable candidates for hydrogen storage. Our results advise site selection choices in geological hydrogen storage in the UK. Our methodology is applicable to any underground porous rock system globally.

How to cite: Thaysen, E. M., Armitage, T., Slabon, L., Hassanpouryouzband, A., and Edlmann, K.: Microbial Risk Assessment for Underground Hydrogen Storage in Porous Rocks, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-1909, https://doi.org/10.5194/egusphere-egu23-1909, 2023.

X4.144

EGU23-13688

ECS

Hydrogen storage pilot: geological characterisation of an onshore aquifer structure in Fife, Scotland

Kate Adie, Niklas Heinemann, Giorgos Papageorgiou, Mark Wilkinson, Stuart Haszeldine, Colin Thompson, and Courtney West

Energy storage technologies are required to support the rapid development and integration of intermittent renewable energy sources into energy systems. Large-scale hydrogen storage in porous formations presents the opportunity to balance seasonal variation in energy demand. This reservoir modelling study aims to establish dynamic capacity estimates for seasonal hydrogen storage. This study investigates a shallow (<1km) sandstone reservoir, of an onshore anticlinal structure in east Fife, Scotland. This storage evaluation supports the geographically proximal H100 pilot rollout of 100% hydrogen for domestic use in 300 volunteer homes (https://www.sgn.co.uk/H100Fife). The target reservoir comprises a partially explored Carboniferous aquifer, thus this study also addresses the challenge of establishing a workflow for the appraisal of storage sites with limited data availability. We aim to maintain low investment costs for this currently immature technology. A static 3D geological model was constructed in reservoir modelling software, PETREL (Schlumberger), informed by data obtained from legacy seismic surveys and from deep boreholes acquired in a hydrocarbon exploration campaign in the 1980s. A sedimentological study was undertaken on the well-known local and regional Carboniferous sedimentology from subsurface information and coastal exposures to characterise reservoir heterogeneity internally – a necessary step to address the large data gaps between sparsely available data points. The reservoir is conceptualised as a 60-70m channelised fluvial sand, with unreactive quartz-arkose mineralogy, interbedded with thin mudstone horizons. The top seal is characterised by silts and mudrock, comprising a widespread maximum flooding surface. Seismic and borehole data has enabled a 3D base case model of stratigraphy and structure. Combined reservoir and structure forms a finite element model exported to CMG’s GEM, used to assess dynamic capacity estimates. Our key research questions are: does the target reservoir exhibit sufficient capacity to support seasonal hydrogen storage based on scenarios informed by industrial experience; what are the cushion gas requirements and associated costs; and what are the key risks and uncertainties influencing capacity estimates. We plan a base case scenario using the most probable geological reservoir and will investigate sensitivity variations around the geology. Benefits from this study include: i) development of a workflow for the hydrogen characterisation of storage reservoirs and the management of risk, whilst minimising initial investment costs, ii) evaluation of cushion gas requirements in a layered reservoir with only a few degrees of dip. Our preliminary results of injection and production will be discussed.

How to cite: Adie, K., Heinemann, N., Papageorgiou, G., Wilkinson, M., Haszeldine, S., Thompson, C., and West, C.: Hydrogen storage pilot: geological characterisation of an onshore aquifer structure in Fife, Scotland, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-13688, https://doi.org/10.5194/egusphere-egu23-13688, 2023.

X4.145

EGU23-7022

Recoverable cushion gas in hydrogen storage as a national gas reserve for energy security

(withdrawn)

Niklas Heinemann

X4.146

EGU23-1044

Hydrogen migration through natural rocks – an experimental approach

Bettina Strauch, Peter Pilz, Martin Zimmer, and Johannes Hierold

The investigation of hydrogen storage options in geological formations is an important part towards the development of technologies for the use of renewable energy. Promising storage capacities are expected in either rock salt deposits or porous sandstone formations with a gas-tight mudstone as cap rock. To obtain crucial data on hydrogen diffusion rates in these rocks, experimental studies are necessary as a first approach.

Here we present an experimental set up comprising two gas chambers, separated by the rock sample under investigation, where the driving force for gas migration through the rock sample is solely the chemical potential (concentration gradient). The hydrogen migration behaviour in samples of dry and wet sandstone, rock salt and mudstone was qualified by hydrogen break-through times and diffusion coefficients. Differences between the rock samples can be clearly seen. Also, the effect that wetted or water-saturated samples have higher retention due to closed pores and microcracks. The break through times varied from half an hour for dry sandstone to 918 hours for wetted rock salt. Based on concentration changes on the permeate side, hydrogen diffusion coefficients were derived in the range from 10^-9 to 10^-7 m²/s. The experimental set up proves to be suitable for determining diffusion parameters in natural rocks.

How to cite: Strauch, B., Pilz, P., Zimmer, M., and Hierold, J.: Hydrogen migration through natural rocks – an experimental approach, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-1044, https://doi.org/10.5194/egusphere-egu23-1044, 2023.

General storage

X4.147

EGU23-13706

IESDB – A comprehensive database of evaporite structures in Iberia

Juan Alcalde, Eloi González-Esvertit, and Enrique Gómez-Rivas

Evaporite rocks are one of the most mined mineral commodities and act as a seals or shaping traps in some of the major hydrocarbon provinces worldwide. In addition, they are also considered as suitable sites for the storage of energy and nuclear waste, being a key asset for the energy transition. Due their historic, present and future value, vast amounts of surface and subsurface information about evaporite structures have been generated by earth scientists, mining and exploration companies or geological surveys in the last century. However, this information is often scarcely useful due to access issues, segregation and scarce dissemination. Here we present the Iberian Evaporite Structure DataBase (IESDB), the first overall assessment focused on evaporite structures developed in any region of the world. The IESDB includes information and figures of 150 outcropping and buried evaporite structures and their surrounding rocks inventoried in Iberia. The Iberian Evaporite Structure Database (IESDB) includes information about the stratigraphy, structure, evolution, geophysical and petrophysical data availability, and mining activity, including a complete set of geological maps, sketches and geological cross-sections. The database targets different evaporite structures, such as undeformed successions, diapirs, evaporite-cored anticlines, evaporite-detached thrusts or allochtonous evaporite bodies. The IESDB is sourced from six different databases and more than 1,500 published and unpublished references, and includes information and figures for each of the 150 evaporite structures inventoried. The IESDB follows the FAIR principles of data management (Findable, Accessible, Interoperable, Reusable) and aims to be a resource for earth science teaching, academic research and resource exploration and appraisal. The IESDB is freely available at https://iesdb.eu

This research was performed within the framework of DGICYT Spanish Project PID2020-118999GB-I00 funded by the Ministerio de Ciencia, Innovación y Universidades/Agencia Estatal de Investigación/Fondo Europeo de Desarrollo Regional. Grants RYC2021-033872-I (Juan Alcalde) and RyC-2018-026335-I (Enrique Gomez-Rivas) funded by MCIN/AEI/10.13039/501100011033 and ESF “Investing in your future”.

How to cite: Alcalde, J., González-Esvertit, E., and Gómez-Rivas, E.: IESDB – A comprehensive database of evaporite structures in Iberia, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-13706, https://doi.org/10.5194/egusphere-egu23-13706, 2023.

X4.148

EGU23-3439

Testing the self-healing capacity of sealant materials for subsurface storage applications.

Reinier van Noort and Viktoriya Yarushina

The secure subsurface storage of fluids, whether energy carriers such as hydrogen or wastes such as CO₂ or nuclear waste, requires sealants that can ensure wellbore seal integrity over timescales of decades to millennia. Currently used sealants are typically based on Ordinary Portland Cement (OPC) technology, which results in brittle seals that may have limited ability to withstand aggressive chemical environments. These properties make it difficult to ascertain that such sealants will maintain seal integrity over the long lifetime of a subsurface storage reservoir, as temperature and/or pressure variations during operations; chemical attack; or geomechanical effects may induce leakage pathways through the seal, as well as along the interfaces between seal and wallrock, or between seal and steel, resulting in a loss of wellbore sealing integrity.

Self-healing sealant materials can be a key technology for ensuring long-term seal integrity in underground storage applications. Such sealants should interact with leaking fluids so that when leakage pathways do form, these pathways are sealed rather than widened. We present experiments in which we aim to test the self-healing capacity of different sealants, particularly for CCS applications, by exposing a reproducible simulated leakage pathway to a flow of CO₂(-bearing fluid) under in-situ conditions. Our simulated leakage pathway consists of a sawcut through a hardened sealant sample, propped with crushed, hardened sealant (though other materials can also be used). Until now, we have focused on OPC-based sealants with various mineral additives (such as olivine and brucite) that result in an increase in solid during carbonation; but other sealants not based on OPC, such as geopolymers, may also be tested. During flow exposure, the pressure drop across the sample is monitored to assess permeability changes. After the experiments, SEM is used to study microstructures and identify reaction products. The results of this experimental work are then used as input for numerical modeling studies that seek to simulate the observed interactions and can extrapolate obtained results beyond laboratory time and length scales. In our model, chemical alteration of the cement is coupled to mechanical deformation and fluid flow to capture the cement system's volume changes that will help mitigate leakages.

How to cite: van Noort, R. and Yarushina, V.: Testing the self-healing capacity of sealant materials for subsurface storage applications., EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-3439, https://doi.org/10.5194/egusphere-egu23-3439, 2023.

X4.149

EGU23-13433

ECS

Large Scale Experiments on the Tightness of Cemented Boreholes under Cyclic Loading

Marcel Schulz, Birgit Müller, and Frank Schilling

The exit from nuclear and fossil-fuel energy and the increase in renewable energy conversion lead to a higher fluctuation in energy supply. To meet the demand in times of energy shortages from sun and wind, this effect can be compensated by extracting and using gas from underground gas storages. As long as enough renewable energy is available, storages can be filled again. However, this results in increasing injection and extraction frequencies, leading to faster occurring pressure and stress changes and therefore posing an additional challenge for reservoir rock, cap rock and technical components.

To evaluate the effects of this additional cyclic loading on the rock-cement-steel-compound, we used an autoclave system on a realistic scale. It simulates abandoned drillings and consists of a 2 m long cemented steel casing with an autoclave system. To simulate injection and extraction, gas pressure (N₂) is applied and released on both ends. Additionally, temperature can be raised up to 100 °C. Between loading cycles, permeability can be measured to determine the effect of pressure and temperature variation on the tightness of the cemented well system.

We present results from the analysis of four cemented casings. Since the hardened cement isn’t connected to the steel casing after experiments, we assume an annular gap as main gas path in most cases. This gap is modelled and fitted to the experimental data. After pressure variations between 0 bar and 60 bar, tightness of the system decreased in every experiment, which leads to an increased modelled annular gap width. Temperature variations between 30 °C and 70 °C didn’t have an effect on the first two casings, but increased tightness and therefore decreased the modelled gap width in the third casing.

Additionally, we observed an anomaly in the second casing, which was extraordinarily tight before the first pressure drop. However, when small amounts of pressure (around 3 bar) were released from an autoclave chamber, around 30 % of the released pressure built up again within a few minutes, while the rest took several hours. We assume a releasing induced gas cooling in the autoclave, while the surrounding warmer steel heats the gas up to the original temperature. This can only be observed for experiments with a rather tight cement-steel plug. In other cases this is not observable because it is superimposed by the pressure build up through the annular gap. The results of finite difference model taken this temperature induced pressure build up into account and are compared to the results of independent permeability and porosity measurements.

How to cite: Schulz, M., Müller, B., and Schilling, F.: Large Scale Experiments on the Tightness of Cemented Boreholes under Cyclic Loading, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-13433, https://doi.org/10.5194/egusphere-egu23-13433, 2023.

X4.150

EGU23-14277

Effect of stress cycling on the deformation and AE characteristics of reservoir rock from the perspective of energy storage: An experimental study

Milad Naderloo, Edgar Hernandez, Kishan Ramesh Kumar, Auke Barnhoorn, and Hadi Hajibeygi

A successful energy transition requires effective storage options. Using underground energy storage (UES), such as depleted porous reservoirs, can help balance the production and demand for renewable energy. Because of the production and injection operations sequence, all underground energy storage systems, including compressed air and hydrogen energy storage, are subject to cyclic loading. To design and operate underground storage facilities, it is essential to understand the geomechanical behavior of porous reservoir rock under cyclic loading. We present the results of the triaxial cyclic laboratory experiments conducted on Red Phaelzer sandstone at 10 MPa confining pressure. By considering three frequencies (F1=0.014 Hz, F2=0.0014 Hz, and F1=0.0002 Hz), two amplitudes (A1=20 MPa and A2=5.9 MPa) and two stress regimes (38 MPa and 85 MPa), 12 triaxial cyclic tests were performed. In total, eight triangular stress cycles were applied for each test, and at the same time, six piezoelectric sensors recorded the acoustic emission (AE) activities during these experiments. Results showed that the total axial inelastic deformation increases when the stress regime and amplitude of cycles are increased. However, this parameter reduces by increasing the frequency of cycles. In addition, Young’s modulus computed from the loading ramps of the cycles increased significantly from the first cycle to the second cycle for all the tests. For tests in the brittle regime, the relation is that the larger the amplitude of cycles, the lower the increase in Young’s modulus. In addition, the AE analysis showed that major events were recorded in the first cycle. By increasing the number of cycles, the number of events, the maximum AE, and the average AE amplitude decreased. Our experimental results highlight that major mechanical changes and AE activities occur during the first cycle, and the stress regime influences the intensity of AE and mechanical changes. These outcomes can benefit studies about subsidence, uplift, fault reactivation, and other physical phenomena impacting the reservoir’s storage capacity, which is affected by cyclic sandstone deformation.

How to cite: Naderloo, M., Hernandez, E., Ramesh Kumar, K., Barnhoorn, A., and Hajibeygi, H.: Effect of stress cycling on the deformation and AE characteristics of reservoir rock from the perspective of energy storage: An experimental study, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-14277, https://doi.org/10.5194/egusphere-egu23-14277, 2023.

X4.151

EGU23-2509

Ice-Inclusion Compounds for Energy Gas Storage

Minjun Cha

Gas hydrates are types of crystalline-inclusion compounds composed by a ‘host’ framework and ‘guest’ molecules. In general, ‘host’ water molecules constitute the hydrogen-bonded host framework, and ‘guest’ molecules, such as methane, ethane, propane, hydrogen, or carbon dioxide, can be encapsulated in the framework structures. Huge amount of gases can be selectively captured in the hydrate structures, and thus; gas hydrates have been received much attention in the energy and environmental fields for gas storage and separation. Here, we introduced the hydrate-forming agents, including cyclic alcohol and amine molecules, for energy gas storage. The guest inclusion behaviors of binary clathrate hydrates were examined by spectroscopic tools, ¹³C solid-state nuclear magnetic resonance (NMR) spectroscopy and powder X-ray diffraction (PXRD) analysis. The storage capacity of methane gas in the binary clathrate hydrates was also examined. The findings, regarding the inclusion behavior of cyclic molecules in hydrate cages, the storage capacity of methane in hydrate structure, and the thermodynamic stability of the binary clathrate hydrates, may provide fundamental information on the complex nature of host–guest inclusion chemistry and lend useful insights with respect to potential gas hydrates applications for gas storage.

How to cite: Cha, M.: Ice-Inclusion Compounds for Energy Gas Storage, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-2509, https://doi.org/10.5194/egusphere-egu23-2509, 2023.

X4.152

EGU23-17538

Evaluation of the geochemical impact of biomethane and natural gasmix injection in sandstone aquifer storage

Camille Banc, Irina Sin, Lau de Windt, and Anelia Petit

EU is seeking to rapidly replace part of the natural gas usually stored in deep saline aquifers
by its renewable analogue, i.e. biomethane. While natural gas is depleted in oxygen, up to
10 000 ppm of O2 can be measured in biomethane. But to date, the geochemical impact of
the injection of a gas mix containing natural gas (thus CH4 and CO2) and biomethane (thus
oxygen) in deep saline aquifer has never been studied. The objective of this study is to
evaluate the resilience of geological storage to oxygen injection and predict the evolution
of the quality of the formation water, the gas plume and the rock formation. To do so,
multiple injection scenarios with various gas quality were tested using multiphase reactive
transport modeling. The gas mixtures were injected in two different deep saline aquifers in
the Paris Basin (France) whose petrophysical and geochemical characteristics were
reproduced during the simulation. Site 1 was a felspathic sandstone with clay cement and
site 2 was a sandstone with clay-calcareous cement.

One dimensional radial flow model evidenced that in both sandstones, the injection of gas
mix induced an acidification of the solution from pH~8 to pH~6. The injected oxygen
originating from biomethane was quickly consumed during pyrite oxidation and
contributed to the acidification of the formation water close to the injection point. However,
the injection of 1% mol fraction of CO2(g) contained in the gas mix was the main acidification
factor. Model demonstrated that the sandstones pH buffering capacity relied upon three
geochemical processes (i) calcite dissolution, (ii) feldspar dissolution and (iii) clays
dissolution and sorption capacity. These three pH-buffers were efficient for oxygen contents
from 10 to 1000 ppm. Models predicted that the gas mix injection could induce minimal but
long-term change in the nature of mineral phases but without significantly impacting the
porosity. Overall, the gas quality was preserved in both sandstones. This result was
evidenced with the modeling of entire gas injection and withdrawal scenario. CO2(g)
exsolution, and to a lesser extent H2S(g) exsolution, could occur during these cycles. In
addition, this study through modeling results concluded that the injection of biomethane
did not significantly change gas-water-rocks interactions compared to those of natural gas
injection. This study also evidenced that the detailed results were largely site-dependent.

How to cite: Banc, C., Sin, I., de Windt, L., and Petit, A.: Evaluation of the geochemical impact of biomethane and natural gasmix injection in sandstone aquifer storage, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-17538, https://doi.org/10.5194/egusphere-egu23-17538, 2023.

Posters virtual: Tue, 25 Apr, 16:15–18:00 | vHall ERE

Chairpersons: Johannes Miocic, Katriona Edlmann, Eike Marie Thaysen

vERE.8

EGU23-3867

ECS

Underground Storage of Natural Gas and CO2 Monitoring Applications

Gabriele Fibbi, Matteo Del Soldato, and Riccardo Fanti

Natural gas is one of the most widely used fossil fuels in the world and it represents an essential element for human activities. It can be stored in underground geological structures such as depleted oil/gas field, aquifers and salt caverns. Underground Gas Storage (UGS) application plays a key role for covering natural gas demand and supply fluctuations, e.g., methane, CH₄, by injecting gas in the summer season when the demand is lower, ready to be withdrawn and deployed into the network to meet increased consumer demand in the winter season. Unfortunately, constant human exploitation of fossil fuels causes climate change phenomenon, creating a potential risk of breaching environmental tipping points with negative consequences. In this regard, the carbon capture and storage (CCS) practice, which is different in methods and purpose from UGS, has been gaining popularity in the last decades. The latter strategy involves storing Carbon Dioxide (CO₂) before it enters in the atmosphere, by means of geological structures for centuries or thousands of years and it can support one of the most important challenges of the twenty-first century, helping the decrement of the global warming and to chase the goal of near-zero greenhouse gas emissions. Misuse of UGS and CCS activities or poor maintenance of injection and withdrawal wells can induce effects of considerable magnitude such as ground deformation, micro-seismic events, fault reactivation and gas leakage. The development of appropriate injection methods and long-term monitoring systems for leak detection is important to verify the integrity of the reservoir, the effectiveness of activities and the respect of safety conditions. In literature approximately a hundred scientific contribution of UGS and CCS monitoring applications were spanning in the world. All the scientific peer-reviewed books and articles, and congress proceedings about the reservoir monitoring in gas storage activities collected and critically analysed show an analytical and statistical overview of the most common use of UGS and CCS, detailing the different goals of these two applications. This research allows displaying the advantages and drawbacks of each monitoring technique involved in gas storage applications by analysing the main UGS and CCS projects. Further developments are required for the UGS monitoring, especially through multidisciplinary approaches useful for identifying possible effects on the surface and gas leaks at depth; meanwhile, CCS solutions are still at an experimental stage, due to the high costs for large-scale applications that require specific researches. The state of the art of these two very different practices can improve the further development of new monitoring approaches or additional methods. The next years will reveal if the CCS methods will be among the leading techniques in the race for energy transition.

How to cite: Fibbi, G., Del Soldato, M., and Fanti, R.: Underground Storage of Natural Gas and CO2 Monitoring Applications, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-3867, https://doi.org/10.5194/egusphere-egu23-3867, 2023.