5. Storage

5.1 The CLIMIT program – Geological CO₂ storage

CLIMIT is at the forefront of advancing CO₂ storage technologies in Norway. As a key initiative focused on safe and efficient geological storage, CLIMIT supports a diverse portfolio of research and development projects. Understanding the complexities of subsurface geology is crucial to prevent leaks and maximize storage capacity, ensuring the long-term success of CCS. CLIMIT actively invests in building expertise and knowledge to address these challenges. To provide a clearer picture of these efforts, we have categorized the storage projects as follows:

5.1.1 Reservoir and caprock

Characterization of reservoirs: Projects that examine various geological formations to assess their suitability for CO₂ storage. This includes studies of reservoir porosity, permeability, capacity, and related properties. For example, different types of sandstone are investigated to determine how much CO₂ they can store and how easily CO₂ can flow through the rock. In addition, the geomechanical properties of the formation are analyzed to evaluate the risk of deformation or fracturing during CO₂ injection.
Caprock integrity: Research on caprock is crucial to ensure it remains impermeable and prevents CO₂ leakage. This involves studying the properties of the caprock and the mechanisms that may affect its integrity over time. There are limited sample data from CCS-relevant caprocks, and increasing our knowledge in this area is important. This includes understanding mechanical properties, mineralogy, and behavior under high pressure and temperature conditions.
Optimization of injection strategies: Studies on how best to inject CO₂ into the reservoir to maximize storage capacity and minimize the risk of leakage. This includes examining various injection rates and pressures, as well as optimizing the placement of injection wells to ensure an even distribution of CO₂ throughout the reservoir.
Pressure management: The development of methods to monitor and control reservoir pressure during and after CO₂ injection. Excessive pressure can cause fracturing or induced seismicity, while too low a pressure can reduce storage capacity. CLIMIT therefore supports the development of advanced sensor systems and models for monitoring and controlling reservoir pressure.

Svein Eggen (Gassnova) and Erik Lindeberg (SINTEF) at Svelvik CO₂ field Lab. Photo: SINTEF

5.1.2 Monitoring and simulation

Development of monitoring technology: Projects that develop and test technology for monitoring CO₂ storage sites, such as seismic methods, gravimetry, and electromagnetic techniques. Seismic methods use sound waves to map the distribution of CO₂ in the reservoir, gravimetry measures changes in the gravitational field caused by CO₂ injection, and electromagnetic methods utilize changes in the reservoir’s electrical conductivity.
Simulation of CO₂ migration: The use of advanced computational models enables simulation of CO₂ dispersal within the reservoir and the prediction of its long-term subsurface behavior. This approach supports comprehensive risk assessment and the optimization of storage strategies. The models integrate a range of parameters, including reservoir properties, injection rates, pressure conditions, and geochemical interactions with CO₂, aqueous fluids, and the host rock.
Verification of storage: The development of methods to ensure that CO₂ remains permanently sequestered within the reservoir is a critical aspect of secure storage. Such approaches may involve integrating various monitoring techniques, including seismic surveys and geochemical analyses, to ensure that CO₂ does not migrate out of the storage formation.

5.1.3 CCS wells

Well integrity: Research on materials and designs for CO₂ injection wells aims to ensure long-term integrity and prevent leakage. This includes developing cement and casings capable of withstanding corrosive conditions induced by CO₂, as well as methods for continuous monitoring of well conditions over extended periods.
Drilling and completion: Optimizing drilling and completion processes for CO₂ injection wells involves the development of drilling techniques that minimize leakage and environmental contamination risks, as well as the refinement of equipment design and installation procedures.
Development of well technologies: Projects focused on advancing CO₂ injection technologies, such as next-generation wellheads and injection valves, seek to enable more precise control over injection rates and pressures, as well as real-time monitoring of well conditions.

5.1.4 Technological development of geological storage

CLIMIT supports research and technology development efforts aimed at improving every stage of the geological CO₂ storage process.

Reservoir characterization: Develop more advanced methods to map and understand the properties of reservoirs, for example by using geophysical techniques and machine learning.
Well technology: Improve the design and construction of wells for CO₂ injection, to ensure long-term integrity and minimize the risk of leaks.
Injection technology: Optimize injection strategies and pressure management to maximize storage capacity and minimize the risk of induced seismicity.
Monitoring technology: Develop more sensitive and cost-effective sensors and monitoring methods to detect potential leaks early.

Åpent kontorlandskap med to personer som sitter med skjermer mot hverandre. Vi ser ryggen til en og skjermen han ser på med grafikk. Foto. — Employees and work at Equanostic in Oslo. Photo: Peter Holgersson AB

5.1.5 Regulations and framework for CO₂ storage

Storing CO₂ is subject to extensive national and international regulations. These measures are essential for ensuring safe, environmentally responsible storage and for facilitating the development and implementation of CCS technology.

Key components in the international regulatory framework

The London Convention Protocol: This international agreement governs the dumping of waste at sea and has been adapted to permit the storage of CO₂ beneath the seabed. Norway has played a pivotal role in these adaptations, which are critical for projects such as Longship.

The OSPAR Convention: This convention protects the marine environment of the Northeast Atlantic and includes regulations for storing CO₂ in geological formations beneath the seabed. Norway actively participates in OSPAR collaboration.
EU directives: The EU has a directive on CO₂ storage that sets requirements for safety and environmental protection. Although Norway is not an EU member, the directive is implemented in Norwegian law through the EEA Agreement.

The UNFCCC: This convention provides the framework for international climate policy and recognizes CCS as an important measure for reducing greenhouse gas emissions.

National regulations

In Norway, CO₂ storage is regulated by a range of laws and regulations, including:

The Pollution Control Act: Sets general requirements for environmental protection and pollution prevention.
The Planning and Building Act: Governs land use and requires environmental impact assessments for CO₂ storage facilities.
The Petroleum Act: Authorizes the granting of permits for CO₂ storage in geological formations.
The CO₂ Storage Regulations: Establish specific safety and environmental requirements for CO₂ storage, including monitoring and reporting obligations.
The Marine Resources Act and the Seabed Minerals Act: Regulate activities on the continental shelf, including CO₂ storage.

5.1.6 CLIMIT’s perspective on the commercialization of CO₂ storage

Several CO₂ storage projects are in the early stages of commercialization, especially in Europe. Northern Lights, as part of the Longship project, has garnered significant international interest. Industrial players in Europe are considering the use of Norwegian infrastructure for CO₂ storage, which may help establish a commercial market for CO₂ storage services. Once Longship becomes operational, it will clarify which technological areas and projects the CLIMIT program should prioritize and invest in. It will also provide valuable guidance to industry and academia on which challenges require further research and innovative solutions.

Further work on the commercialization of CO₂ storage

Optimization of storage technologies: There is a need for additional research to improve the efficiency of every stage in the storage process. This includes enhancing injection technology, optimizing well design, and developing safe, effective methods for monitoring stored CO₂.
Economic sustainability: To make CO₂ storage economically viable, storage costs must be reduced. CLIMIT will continue to focus on this by supporting research into new technologies and solutions.
International collaboration: Ongoing cooperation among countries and regions to build a shared infrastructure for CO₂ transport and storage is essential. CLIMIT plays a key role, particularly through its support for projects that connect international partners.
Scaling: Future efforts must emphasize scaling up existing projects so that CO₂ storage can handle larger volumes as CCS technologies are more widely implemented.

CLIMIT plays a vital role by supporting research and development in CO₂ storage, particularly in risk reduction and the development of cost-effective solutions. The program’s goal is to enable a full-scale CCS infrastructure that can help achieve national and international climate targets, with CO₂ storage serving as a key component. Future projects will continue to focus on building the necessary infrastructure to safely and efficiently store large volumes of CO₂.

On the international stage, CLIMIT promotes collaboration through knowledge exchange and support for innovation across borders.

5.2 CLIMIT program category – Reservoir and caprock

For effective and secure CO₂ storage, it is critical to understand and address challenges related to the reservoir and caprock. These geological formations are essential for ensuring permanent CO₂ sequestration and preventing leakage. CLIMIT supports research addressing these challenges within the “Reservoir and caprock” program category.

5.2.1 Challenges

Reservoir characterization: Accurate characterization of reservoir properties, such as porosity, permeability, and storage capacity, is crucial for predicting CO₂ migration and optimizing injection strategies. Uncertainty in reservoir characterization can lead to inefficient storage or increased leakage risk.

Caprock integrity: The caprock must remain sufficiently impermeable to prevent CO₂ leakage over geological timescales. Faults, fractures, and other geological structures may compromise caprock integrity and increase leakage risk.

Geochemical reactions: Interactions between CO₂, formation water, and rock can alter reservoir properties and potentially affect storage security. For example, the mineralization of CO₂ can reduce reservoir porosity and permeability over time.

Induced seismicity: CO₂ injection can cause small seismic events (induced seismicity). Although these are usually too weak to cause surface damage, they may potentially affect caprock integrity and increase the risk of leakage.

5.2.2 The status on reservoir and caprock research

Several CLIMIT-funded projects have sought to improve the understanding of reservoir and caprock issues in CO₂ storage, developing solutions to address these challenges:

Longyearbyen – the most Northern settlement in the world.

5.2.2.1 A frozen frontier – Exploring CO₂ storage in Longyearbyen

The Longyearbyen projects, led by UNIS (The University Centre in Svalbard), represent a notable research effort to explore and develop technologies for CO₂ storage in Arctic regions. Since 2007, these projects have pioneered CO₂ storage research with the ambitious goal of creating a local solution to reduce emissions from Longyearbyen’s coal-fired power plant, while advancing fundamental research and methods with global implications. Although the project did not result in large-scale storage in Svalbard, it provided valuable research and competence building.

Visionary researchers recognized that Longyearbyen, characterized by high per-capita CO₂ emissions, could lead a climate-friendly innovation. With CLIMIT support and collaboration with industrial partners, including Store Norske, Statoil, and several international oil companies, extensive investigations and tests were conducted. These involved top Norwegian research institutions—such as the University of Oslo, NTNU, SINTEF, and various FME centers—resulting in strong foundations in CO₂ storage research and valuable insights that inform subsequent projects.

By drilling wells, conducting geophysical measurements, and performing pressure and fluid-flow tests, researchers gained a detailed understanding of the Adventdalen geology and reservoir complexity. Adventdalen, with its fractured and low-porosity rock, proved to be an “unconventional” reservoir. The results from Longyearbyen provide insights applicable to similar geological conditions worldwide. In addition to extensive water-injection tests, the researchers conducted experimental CO₂ injection trials to evaluate capacity and sealing conditions. Although technically challenging, these efforts led to new flow models and reservoir characterizations useful for other CCS projects.

Despite not achieving large-scale CO₂ storage, the Longyearbyen projects significantly advanced the CCS field in Norway and globally. They contributed to shaping Norway’s role as a leading actor in CO₂ storage, strengthening domestic competence and infrastructure. This knowledge is invaluable and has created a bridge to larger projects, such as Northern Lights, which will store CO₂ from industrial sources on the Norwegian mainland beneath the North Sea. The Longyearbyen projects served as a research platform and pilot initiative, demonstrating how Norway can pursue ambitious climate targets through CO₂ storage.

Over many years, these projects also inspired international research communities. Svalbard became a venue for global collaboration, and the resulting research network strengthened international capacity in carbon storage. The wealth of data collected in Longyearbyen continues to influence the CCS field, aiding in technology and method development worldwide.

5.2.2.2 Optimized CO₂ storage in sloping aquifers (Upslope)

The CO₂-Upslope project (2017-2019), led by the University of Oslo,investigated the potential for storing CO₂ in geological formations on the Norwegian continental shelf, specifically focusing on sloping aquifers. These are tilted, water-filled layers of porous rock that can trap CO₂through dissolution in water and chemical reactions with minerals. The project aimed to improve understanding of the long-term physical and chemical behavior of CO₂ during storage and develop new methods for simulating and optimizing CO₂ storage in these formations.

Research and Innovations

The project employed an interdisciplinary approach, combining geological analysis, geophysical techniques, and numerical modeling. Key research activities included:

Developing a new geological model for the Gassum Formation, a sloping aquifer in the Skagerrak basin.
Evaluating the mineralogy and reservoir properties of the Gassum Formation.
Developing and applying new models to estimate the amount of CO₂ that dissolves in water, becomes bound in minerals, and is trapped during migration in sloping aquifers.
Developing models for estimating salt precipitation during injection.

Significance and Implications

The CO₂-Upslope project yielded significant insights with implications for safe and effective CO₂ storage in sloping aquifers:

Enhanced understanding of CO₂ trapping: The project improved understanding of various CO₂ trapping mechanisms (dissolution, mineralization, and stratigraphic trapping) in these dynamic geological formations.
Improved storage capacity estimation: New models and methods were developed to estimate the CO₂storage potential of sloping aquifers more accurately.
Increased confidence in CCS: The project’s findings contribute to greater confidence in the long-term safety and feasibility of CO₂ storage in sloping aquifers, supporting broader acceptance of CCS as a climate mitigation strategy.

Conclusion

The CO₂-Upslope project has successfully advanced the understanding and modeling of CO₂ storage in sloping aquifers. The project’s interdisciplinary approach, combining geological analysis, geophysical techniques, and numerical modeling, has led to the development of new tools and knowledge that can be applied to various storage sites. By improving the estimation of storage capacity and enhancing confidence in the long-term safety of CO₂ storage, CO₂-Upslope contributes significantly to the advancement of CCS technologies and supports efforts to achieve climate goals..

Oljeplattform i havet. Foto. — Photo: Ole Jørgen Bratland

5.2.2.3 The SWAP projects: Groundbreaking steps toward future CO₂ storage

As global efforts in carbon capture and storage intensify, Equinor has taken important steps on the Norwegian continental shelf to ensure substantial future CO₂ storage capacity. Through the SWAP (Strategic Well Acquisition Project) and SWAP2 projects, supported by CLIMIT, Equinor explored large-scale CO₂ storage potential near the Troll field, focusing on the Smeaheia area and the Horda Platform. These projects represent decisive actions toward realizing cost-effective, safe storage solutions at scale.

Initiated in 2019, the first SWAP project included an exploration well in license PL921, an area east of the Troll field and near the Aurora CO₂ storage site. Drilling in the Gladsheim structure offered a unique opportunity to gather extensive geological data from a dry well that showed significant CO₂ storage potential. Rather than focusing solely on hydrocarbon potential, Equinor collected additional data typically not acquired during exploration drilling.

A key goal was to verify the sealing quality of the primary caprock, the Draupne Formation. The results were positive, confirming that the reservoir has high capacity and is suitable for CO₂ storage.

“The data suggest the seal is solid. The reservoir has thick, laterally extensive rock units, indicating that the area may potentially accommodate large volumes of CO_₂.”

Project leader Rune Thorsen in 2020 (translated from Norwegian)

These findings may also benefit Northern Lights.

“With future scaling of Northern Lights, the area we are exploring could likely serve as a storage location. This means we might utilize the infrastructure built in the initial project phases, resulting in significant cost savings.”

According to Thorsen 2020 (translated from Norwegian)

SWAP2 – The next step in a strategic journey

Two years after SWAP, Equinor followed up with SWAP2, focusing on exploration well 31/11-1 in license PL785S at the Stovegolvet prospect, south on the Horda Platform. Data were collected from the Johansen Formation, a reservoir analogous to that used in the Northern Lights project. The objective was to verify the sealing quality of the primary caprock formations, the Draupne and Drake shales, and confirm large-scale storage potential in regionally extensive Jurassic sandstones.

Kart over Smeaheia. Grafisk illustrasjon. — Illustration: SINTEF

Smeaheia – A monumental hub for CO₂ storage

Through the SWAP projects, the understanding of the Smeaheia area improved significantly, revealing conditions highly favorable for CO₂ storage. Extensive pressure measurements showed that the reservoir is well-suited for CO₂ storage and communicates effectively with the Troll field. This means it can receive large volumes of CO₂ without excessive pressure buildup.

Over time, Equinor’s efforts may establish a storage solution in Smeaheia with a capacity of up to 20 million metric tons of CO₂ per year.

Economic and strategic advantages

The SWAP projects were designed to accelerate CO₂ storage commercialization. Early access to geological data enables Equinor to bypass the need for a dedicated verification well, potentially saving hundreds of millions of kroner and significantly reducing uncertainty in the CO₂ storage process. With CLIMIT support, Equinor executed both SWAP and SWAP2, contributing essential knowledge for CCS efforts on the Norwegian continental shelf.

“CLIMIT’s financial contributions made SWAP and SWAP 2 possible. Without this support and the exploration drilling results, CO_₂ storage at Smeaheia would likely have been delayed by several years.”

Thorsen emphasized (translated from Norwegian)

Catalyzing a sustainable future for industry

These projects show that the Norwegian continental shelf can play a central role in future carbon storage. The data collected will not only aid Northern Lights, but also other new entrants aiming to contribute to a sustainable transition.

The SWAP projects demonstrate how exploration of dry wells, often considered a disappointment in oil and gas contexts, can uncover new opportunities in CO₂ storage. Equinor and its partners have shown that the Norwegian shelf is ready to meet future demands for safe, large-scale storage solutions.

5.2.2.4 Geological storage of CO₂: Mathematical modeling and risk assessment (MatMoRA-II)

From 2012 to 2017, the University of Bergen led MatMoRA-II, a project addressing key questions about capacity, long-term safety, and risk in geological CO₂ storage. Funded by CLIMIT, its goal was to improve numerical simulations of CO₂ storage, with particular focus on thermal, mechanical, and hydrodynamic processes.

Research and development
The project developed new numerical methods and models to handle complex and realistic scenarios in CO₂ storage. These models included:

Reduced models that can efficiently simulate the thermal and geomechanical effects of CO₂ injection.
Advanced simulations of CO₂ dissolution and flow in low-permeability structures.
Studies of how the topography and integrity of the caprock affect CO₂ migration.

The project integrated several research tasks, including the development of reliable frameworks for software implementation and methods for fast and accurate simulation of fundamental flow physics. This enabled the coupling of different physical processes that are often dependent on specific reservoir conditions.

Significance and results
MatMoRA-II contributed to the development of world-class modeling tools that enable comprehensive risk assessments. These tools improve the understanding of potential CO₂ storage sites in Norway, strengthening Norway’s position in CCS technology.

The new models provide insights into how CO₂ behaves under different pressure and temperature conditions, and they enable more accurate estimates of storage capacity and risk. In particular, the project has delivered methods for simulating coupled phenomena such as thermal expansion, capillary effects, and mechanical deformation, which are critical factors in assessing storage integrity.

Further implications
MatMoRA-II has laid the foundation for future research projects and the development of safe and effective CO₂ storage. By combining advanced mathematical models with practical applications, the project has contributed to reducing the risks and costs of large-scale CO₂ storage. The project also highlights the importance of robust numerical simulation as a tool in CCS.

5.2.2.5 Safe long-term storage sealing of CO₂ in hydrate

From 2013 to 2018, the University of Bergen led a research project exploring the storage of CO₂ in hydrate structures, under the guidance of Professor Bjørn Kvamme. The aim was to understand the mechanisms enabling stable CO₂ storage in hydrates while potentially releasing methane from natural gas hydrates. The project employed a multi-scale modeling strategy, from quantum mechanics to large-scale simulations, to elucidate the processes governing CO₂ storage and conversion within hydrates.

Research and results
The project focused on two main mechanisms for CH₄/CO₂ exchange in hydrate structures:

A solid-state exchange where CO₂ causes melting of outer hydrate layers, releasing CH₄, and then CO₂ is trapped in a new hydrate structure.
Formation of new CO₂ hydrate with free water in pores, which releases heat and accelerates the melting of CH₄ hydrate.

The project also explored how minerals affect water structures and adsorption of CO₂ and CH₄, as well as how the permeability of formations changes when CO₂ hydrate forms. Studies showed that the formation of CO₂ hydrates reduces permeability, which creates a dynamic balance between melting and formation of hydrate. The results were published in several scientific articles and attracted international interest.

International impact
The project has generated significant international attention, including from China, where Professor Kvamme has been invited to assist in the development of their hydrate energy program. Collaboration with the University of California has brought together three hydrate research groups to explore CO₂ storage in hydrates, and the project has contributed to the development of zero-emission concepts for hydrogen production using methane from hydrates.

Significance and implications
The project has established a new understanding of the mechanisms, stability, and economic benefits of CO₂ storage in hydrates. The research has laid the foundation for the commercialization of zero-emission concepts and created international collaboration opportunities in both energy production and climate innovation. Hydrate storage of CO₂ is proving to be a robust and stable solution that can contribute to global climate goals while providing valuable energy in the form of methane.

Through the combination of experiments, modeling, and international collaboration, the project has paved the way for further research and commercialization of technology for safe and effective CO₂ storage in hydrate reservoirs.

5.2.2.6 Protection of caprock integrity for large-scale CO₂storage (PROTECT)

The PROTECT project (2014–2018), led by Uni Research AS, aimed to investigate and ensure the integrity of caprock during large-scale CO₂ storage in saline aquifers. CO₂ injection increases reservoir pressure, which can lead to caprock fracturing or reactivation of existing faults. The project addressed these challenges through laboratory studies, numerical modeling, and field data to enhance the understanding of geomechanical processes affecting caprock stability.

Research efforts and results

PROTECT conducted extensive laboratory testing on shale and mudrock samples from the North Sea and Svalbard, including naturally fractured caprock. The experiments analyzed caprock responses to pressure, temperature, and supercritical CO₂ exposure. Findings showed that CO₂ can absorb water from shale, causing the rock to shrink and increasing fracture permeability. In contrast, the presence of liquid water significantly reduced rock strength, highlighting the complexity of fluid-rock interactions.

Numerical models were developed to simulate fracture mechanisms, fluid flow, and thermal effects in the caprock under CO₂ injection. These models were employed to assess the injection capacity of the Utsira Formation, a key resource for Norwegian CO₂ storage. Results indicated that the Utsira Formation could sustain injection rates up to 100 times the current rate at the Sleipner project, provided pressure limits are maintained.

The project also advanced monitoring techniques by integrating seismic, electromagnetic, and gravimetric data to improve the detection and tracking of CO₂ migration and pressure changes in the reservoir. These innovations enhanced data interpretation and yielded more reliable predictions of CO₂ storage safety.

Significance and implications

The PROTECT project has delivered valuable tools and insights to support the development of safe and cost-effective CO₂ storage operations. The project outcomes enable industry stakeholders to optimize injection strategies and mitigate risks associated with leakage and pressure-related issues in the caprock.

Through the education of two PhD candidates and one master’s student, the project has also contributed to building national competence in CCS. This effort reinforces Norway’s position as a global leader in carbon capture and storage and supports the country’s climate ambitions to reduce greenhouse gas emissions.

5.2.2.7 CO₂ storage in the North Sea: Quantification of uncertainties and error reduction (CONQUER)

Between 2015 and 2019, NORCE led the research project CONQUER, which focused on quantifying uncertainty and reducing errors related to CO₂ storage in the subsurface. The project, funded by the CLIMIT program, aimed to develop simulation tools and methods to manage uncertainties related to geological data, modeling, and operational decisions for safe and effective CO₂ storage, particularly in the North Sea.

The project investigated key processes such as pressure buildup during injection, long-term migration of CO₂, and leakage risk through the caprock. To address these challenges, mathematical models were developed that could simulate CO₂ transport in reservoirs, taking into account uncertainty in physical parameters and models for dissolution and leakage. Uncertainty quantification was implemented through advanced numerical techniques such as polynomial chaos and multiresolution analysis, as well as by using reduced-physics models that combined simplified calculations with precise estimates of uncertainty.

The project also developed geomechanical models for simulating pressure and mechanical deformation in the reservoir and caprock, especially with regard to scenarios that can lead to leakage. An important result was the release of an open-source software for poromechanics, the study of the behavior of fluid-filled porous materials, which is compatible with SINTEF’s Matlab Reservoir Simulation Toolbox. This software will be important for future research and industrial applications in CCS.

Through collaboration with international partners such as the University of Colorado Boulder and using data from the Sleipner and Snøhvit storage fields, CONQUER contributed to developing a better understanding of CO₂ storage. The project also popularized the research through, among other things, an article in Bergens Tidende, which explained how uncertainty in CO₂ storage can be managed.

The CONQUER project has strengthened the foundation for large-scale CO₂ storage by reducing uncertainty and improving the basis for operational planning decisions. This contributes to safer and more cost-effective implementation of CCS technology and positions Norway as a leader in carbon capture and storage. The results also have broader applications, including modeling microplastic dispersal and clean combustion technology. By combining advanced simulation tools and field data, the project has paved the way for future research and industrial solutions that are crucial for meeting global climate challenges.

Ugjenkjennelig person som peker på et CO2 symbol. Foto.

5.2.2.8 CO₂ seal bypass

Between 2015 and 2018, the University of Oslo led a research project focused on understanding how CO₂ migrates through reservoir rocks and sealing layers in the subsurface. Funded by the CLIMIT program, the project aimed to improve the safety and efficiency of geological CO₂ storage, with a particular focus on future storage sites in the North Sea.

Research and results
The project investigated the dynamics of reservoirs and sealing layers by analyzing natural CO₂ flows and leakage patterns in sandstone formations. The research was based on field studies conducted in Utah, USA, where natural laboratories provide insights into how CO₂ interacts with subsurface rocks. Observations from this region, combined with data from sites with active CO₂ leakage, were used to map flow and changes in sandstones under pressure and temperature conditions resembling those in deep reservoirs.

The project integrated fieldwork, laboratory studies, and numerical modeling. By implementing field data into 3D simulation models, the researchers identified critical factors influencing flow and leakage, including diagenetic status and rock strength. These models are invaluable for planning and evaluating storage sites and for developing strategies to prevent and mitigate leakage.

The project also contributed to the education of a new generation of geologists, with 11 MSc students and one PhD student completing theses based on project data. Results have been published in scientific journals and presented at international conferences.

COPASS – CO₂ Seal and Bypass: The Bartlett Fault, Utah. The fault juxtaposes the Entrada and Morrison formations, and has partially sealed in the CO₂ charged groundwater that migrated through the porous sandstones of the Entrada Formation. Photo/ill: Ivar Midtkandal

Significance and implications
The CO₂ Seal Bypass project has provided new insights into how CO₂ migrates in complex geological systems. This knowledge is essential for ensuring the safe storage of CO₂ in future large-scale projects, particularly in regions like the North Sea. By combining field observations with advanced modeling, the project has laid the groundwork for improved planning and monitoring of storage sites.

Following the project’s conclusion, researchers have begun exploring new challenges, including how extensive fracture systems influence CO₂ flow in the subsurface. This demonstrates how the project has not only contributed critical knowledge but also inspired further research.

Karbondioksidmolekyl vist i blått. Illustrasjon

5.2.2.9 Avoiding loss of CO₂ injectivity

Between 2016 and 2018, SINTEF led a research project, funded by the CLIMIT program, which aimed to understand and prevent loss of injectivity in CO₂ storage wells. The main focus was to investigate how the mechanisms of salt precipitation and hydrate formation can affect reservoir permeability and thus the injection capacity in CO₂ storage reservoirs.

Through experimental studies and numerical modeling, it was investigated how salt precipitation and hydrate formation occur under different reservoir conditions. The project conducted experiments with sandstone cores where supercritical CO₂ was injected to study precipitation mechanisms. Salt precipitation was observed, but the amount was not large enough to significantly reduce injectivity. Hydrate formation, on the other hand, proved in several cases to be able to lead to complete clogging of pores and loss of injectivity. This process was studied at both core and pore scale using advanced imaging techniques such as magnetic resonance imaging and micro-models.

On the numerical side, the project developed a multiphase model that simulated flow and thermodynamics in CO₂-water-salt/hydrate systems. The model used advanced thermodynamic equations and was validated against experimental data. The model provides insight into how injection parameters such as temperature, pressure, and composition affect the risk of clogging.

Significance and implications

The results from the project have significant implications for large-scale CCS operations:

Increased operational reliability: The insights contribute to ensuring continuous and efficient injection, which reduces the need to drill new wells and increases economic sustainability.
Improved storage security: The studies on hydrate formation indicate that CO₂ hydrates can act as a secondary seal, which strengthens confidence in the long-term safety of CO₂ storage.
Innovative tools: The developed simulation tool provides the industry with better opportunities to optimize injection strategies and reduce the risk of loss of injectivity.

5.2.2.10 Stress path and hysteresis effects on integrity of CO₂ storage site (SPHINCSS)

The SPHINCSS project (2017–2020), led by SINTEF, investigated how stress changes and hysteresis effects affect the safety and integrity of CO₂ storage sites. The project aimed to understand how geomechanical changes in the reservoir rocks, caprocks, and surrounding faults are influenced by CO₂ injection. This is critical to assessing the safety of both aquifers and depleted oil and gas reservoirs as storage sites.

The research included laboratory experiments and modeling to assess how variations in pore pressure, stresses, and temperature affect reservoir behavior. Draupne shale, donated by Equinor, was used as a test material to assess the mechanical and chemical effects of exposure to CO₂ in various states, including dry CO₂, CO₂ dissolved in brine, and supercritical CO₂. The tests showed that the strength of the shale is minimally weakened by dry CO₂, while CO₂ dissolved in brine led to somewhat greater, but still limited, weakening.

They will examine potential mechanisms that lead to increased stresses in and around the storage reservoir. Photo: SINTEF

Results and findings

Laboratory tests revealed how CO₂ affects the strength and stiffness of rocks. Cyclic tests showed small changes in mechanical properties, indicating that the risk of shear fractures in the caprock is very low.
Modeling of geomechanical changes, including fracture risk along faults, showed that depletion of oil and gas reservoirs can lead to irreversible stress concentrations. When refilled with CO₂, this can increase the risk of leakage along faults. Aquifers proved more resistant to pressure changes.
Experiments on natural fractures in Draupne shale showed that the fractures can “heal” under deformation, which reduces the risk of leakage.

Significance and recommendations

The project has provided important insights into how different rocks and reservoir types react to CO₂ storage. The results contribute to a better understanding of how stresses and pressure variations should be managed to ensure safe storage.

The project recommends more comprehensive modeling and characterization of faults in larger storage projects and has increased confidence in CCS as a reliable technology for large storage volumes.

5.2.2.11 Understanding of CO₂ dissolution in oil by convection-driven mixing and wettability alteration (UNCOVER)

The UNCOVER project (2017–2021), led by NORCE Norwegian Research Centre AS, aimed to investigate the physical processes related to CO₂ dissolution in oil and water in porous reservoir rocks. The project focused on how convection-driven mixing and changes in the wettability of the rocks affect CO₂ storage and oil recovery, with laboratory experiments as the central method.

Research and results

Using a unique experimental setup, the project developed a comprehensive dataset that provides insights into how CO₂ mixes with oil and water under realistic reservoir conditions. The experiments were carried out in a custom-made 2D model, in addition to core flooding experiments to study flow patterns in real rocks. The results from the experiments showed:

How convection-driven mixing accelerates CO₂ dissolution in oil and water, and how this affects fluid flows in the reservoirs.
How changes in the rock’s wettability affect the interaction between CO₂, oil, and water.
The importance of gravity currents and convective mixing during the displacement of oil with CO₂.

The dataset was used to validate numerical models developed in collaboration with the Open Porous Media (OPM) initiative. These models provide more accurate predictions for CO₂ storage and enhanced oil recovery at the field scale.

5.2.2.12 Nanoparticles for stabilizing CO₂ foam for combined storage and energy production from mature oil fields

The project, led by the University of Bergen between 2018 and 2022, investigated how carbonate reservoirs can be used for safe storage of CO₂ while enabling energy production from mature oil fields. This was a laboratory-based study that focused on dissolution mechanisms and flow dynamics in carbonate reservoirs – a rock type known for its high reactivity and heterogeneous pore structure, which can create challenges for safe storage.

Using advanced experimental methods and new technology, the researchers studied how CO₂ affects carbonate reservoirs. The project uncovered important mechanisms for how reactive transport processes can lead to rock dissolution and the formation of leakage points. At the same time, the researchers developed technologies to stabilize CO₂ foam using nanoparticles, which can seal leakage pathways and contribute to effective CO₂ storage.

Results and findings

The project established new experimental methods to study reactive transport processes in carbonate reservoirs at both the pore and core scale.
A new mechanism was identified: CO₂ as a reaction product can encapsulate carbonate particles and prevent further local dissolution. This discovery challenges previous assumptions and provides new insights into how storage formations behave.
The development of imaging technologies to track CO₂ flow at the Darcy scale contributed to improved understanding of preferred flow paths and reservoir integrity.

Implications

The findings have implications beyond CCS, including applications such as groundwater flow, radioactive waste management, and oil recovery.

5.2.2.13 Preventing loss of near-well permeability in CO₂ injection wells

This project (2018-2023), led by SINTEF, focused on understanding and preventing permeability reduction near CO₂ injection wells. The research addressed challenges related to salt precipitation and other mechanisms that can lead to pore clogging in reservoir rocks, which can reduce the efficiency and safety of CO₂ storage.

When dry CO₂ is injected into porous rocks containing brine, the water can evaporate, leading to the precipitation of salt crystals that clog the pores. This project developed models and conducted experiments to better understand this process and propose solutions.

Results

Modeling of salt precipitation: Development of an equation of state to predict the conditions under which salt precipitation occurs. This was implemented in the open-source simulation code MRST and used to model the effect of salt crystals on permeability.
Experimental studies: Small-scale injection experiments with different rock types were performed to investigate how factors such as flow rate, direction, and brine type affect precipitation and clogging. The results were validated through scaled-down well tests in realistic geometries.
Mitigation measures: Testing of chemical methods to counteract injection-related losses in permeability.
Integration into simulation tools: The results were used to predict losses in injection capacity under field conditions, especially for pilot projects like Smeaheia.

Significance and implications

The project developed a deeper understanding of the mechanisms of salt precipitation and how this affects flow properties in the reservoir. Important contributions include:

New knowledge about how salt precipitates and affects permeability.
Understanding of how different geological and operational conditions affect the risk of clogging.
Tools to simulate and predict injection efficiency under different scenarios.
Practical recommendations for operators, including measures to minimize the risk of clogging in specific
reservoirs.

Faults in CO₂ storage reservoirs. Illustration NGI

5.2.2.14 Quantification of fault-related leakage risk (FRISK)

The FRISK project (2019–2023), led by the Norwegian Geotechnical Institute (NGI), developed new knowledge and tools to assess the risk of CO₂ leakage along faults in reservoirs under consideration for carbon storage. The project focused on understanding and modeling fluid flow in faults, particularly with regard to structural uncertainties and changes in reservoir pressure during injection.

The project addressed a significant technological challenge related to the assessment of fault zones as potential CO₂ storage sites, especially in areas such as the Horda platform and Smeaheia in the North Sea. The work included theoretical research, experimental analyses, and field studies.

Results

Fault modeling: Development of methods for mapping and quantifying fault complexity, based on geometry, growth history, and properties that affect sealing capacity.
Flow properties in faults: New tools were developed to calculate fault permeability and simulate fluid flow in single- and two-phase systems.
Studies of the Vette Fault Zone: In the Smeaheia area, analyses showed that small fluid volumes can migrate upwards along thin faults, but that overlying stratigraphic layers with high clay content act as good caprocks.
Risk assessment: Models for quantifying leakage risk and identifying key parameters that control uncertainty were developed and tested.
Dissemination: The results were shared at meetings, conferences, and in peer-reviewed publications, and have been well received by both academia and industry.

Achieved effects

FRISK has contributed to an improved workflow for risk analysis of faults in CO₂ storage projects. The developed tools and models make it possible to assess leakage risk more accurately and identify faults with properties that enable safe storage. The study of the Vette Fault Zone has provided valuable insights into the sealing capacity of faults in the North Sea, although it remains to qualify these reservoirs as storage sites.

5.2.2.15 Overburden analysis and seal integrity study for CO₂ sequestration in the North Sea (OASIS)

This project (2018-2023), led by the University of Oslo, aimed to understand how caprocks and overlying layers can ensure safe and permanent CO₂ storage in the North Sea. The project focused on areas like Smeaheia, east of the Troll field, and developed methods and tools to assess storage capacity, injection properties, and the mechanisms that prevent leakage.

Through the analysis of geological data like core samples, wireline logs, and seismic data, detailed 3D geomechanical models were developed to assess the risk of fracturing and leakage. Laboratory tests on rock samples provided insights into mechanical properties such as Young’s modulus and Poisson’s ratio, while petrographic analyses revealed the mineralogy and sedimentary processes. This formed the basis for a comprehensive evaluation of the sealing integrity of caprocks and the overburden.

The project also utilized stochastic seismic inversion to map variations in rock properties. Methods for assessing pressure buildup and reducing leakage risk were developed, which have direct relevance for future storage projects. In addition, OASIS contributed to competence development by educating Ph.D., Postdoc, and MSc students in CCS technology.

**Figure:** Map showing three potential CO₂ storage sites of Smeaheia, Heimdal and Utsira in the North Sea (left). The depth map of the Sognefjord Formation (the main sandstone reservoir in the Smeaheia area, Source: Gassnova) based on a combination of the low density 2D seismic and high density 3D seismic interpretations (right). (See better version).

Significance and implications

The results from OASIS include a better understanding of storage capacity and safety in CO₂ storage, the development of tools for risk assessment, and practical solutions that can be used in existing and future CCS projects on the Norwegian continental shelf. The project has delivered important knowledge and innovation that supports the safe implementation of large-scale carbon storage.

5.2.2.16 Reusing depleted oil and gas fields for CO₂ sequestration

The RETURN project (2021–), led by SINTEF, is working to enable large-scale storage of CO₂ in former oil and gas reservoirs with low pressure after production. The project brings together partners from Norway, the Netherlands, Great Britain, Germany, Italy, and Canada, and addresses technical challenges to make the reuse of such reservoirs safe, efficient, and cost-effective.

Old oil and gas fields are ideal for CO₂ storage due to their well-known geological properties and low pressure, which reduces the risk of leakage. RETURN focuses on overcoming challenges related to the injection of cold CO₂, which can lead to freezing, hydrate formation, and phase transitions that clog pore networks and hinder injection.

Expected effects

RETURN expects to contribute new knowledge and tools to monitor and manage challenges in injecting CO₂ into depleted reservoirs. The project focuses on:

Reducing the risk of stress and leakage associated with temperature and pressure changes.
Methods to minimize plugging and maintain well integrity during injection.
Practical solutions for cost-effective reuse of reservoirs as long-term storage sites for CO₂.

5.2.2.17 THERMESI – Thermal Effects on Seal Integrity

The project, led by NGI, started in 2024 and focuses on understanding how the injection of cold CO₂ into warm reservoirs affects the integrity of the caprock. Geological storage of CO₂ is crucial to achieving climate goals, but large-scale injection involves thermal and mechanical stresses that can increase pore pressure and weaken the stability of the storage complex. The purpose of THERMESI is to illuminate the risk of the caprock losing stability due to thermal loads, and to develop advanced numerical models that can predict and manage such changes.

Activities and results

The project conducts laboratory and full-scale experiments to investigate how thermal stresses affect caprock materials and the interface between the reservoir and the caprock. These experiments are validated against detailed mathematical models, which are further expanded to regional-scale simulations to assess the implications of thermal effects on geomechanical stability and leakage risk. The results are shared in the form of scientific articles and conference contributions, with the aim of ensuring safe and effective CO₂ storage by maintaining the stability of the caprock.

Enhanced oil recovery (EOR). Illustration

5.2.2.18 Beyond the barrel – From oil recovery to climate recovery

The use of CO₂ for enhanced oil recovery (EOR) has been part of the oil industry’s technology portfolio for decades. On the Norwegian continental shelf, EOR has been explored through extensive studies and research, but without being realized in practice. Although CLIMIT and other actors are now shifting their focus towards more environmentally friendly alternatives such as CO₂ storage in saline aquifers, EOR projects have nevertheless contributed to significant knowledge development in CO₂ handling and reservoir technology. This makes them an important part of our overall experience with CCS.

A legacy of potential and its inherent challenges

Studies conducted by both operators and research institutions have shown significant potential for increased oil recovery using CO₂ injection. For example, it was demonstrated that EOR can increase recovery by 4-7% in fields such as Ekofisk, Gullfaks, and Draugen. At Ekofisk alone, a 1% increase in recovery corresponds to approximately 80 million barrels of oil equivalent – a significant gain.

The technical mechanism behind CO₂-EOR is impressive. Under miscible conditions, CO₂ and oil can form a single phase. This reduces interfacial tension and makes the oil easier to produce. In addition, CO₂ mobilizes previously immobile oil volumes. This makes EOR a very effective method under the right conditions.

Despite promising results, challenges with access to large and secure CO₂ sources, as well as high demand for investments, have made it difficult to realize such projects in Norway. Ekofisk and Gullfaks alone would have required at least 5 million tons of CO₂ annually for a full field implementation – an amount that has been challenging to obtain in a cost-effective manner.

Bubbles with benefits

CO₂ foam technology is an innovative method used in EOR and CO₂ storage to improve the efficiency and sustainability of these processes. It works by combining CO₂ with surfactants (soap-like chemicals) that form a stable foam in the reservoir. This foam controls how CO₂ flows through the subsurface, preventing the gas from moving too quickly or uncontrollably through high-permeability channels. The foam allows CO₂ to be distributed more evenly in the reservoir, so that more oil is pushed towards the production wells. The foam ensures that larger amounts of CO₂ remain permanently stored in the reservoir. This helps to reduce greenhouse gas emissions. By using CO₂ foam, oil recovery increases while injection costs are reduced. This makes the process more attractive to the industry. In some cases, the technology can achieve carbon-negative oil recovery, where more CO₂ is stored than is released in the process. CO₂ foam technology can be used in different reservoir types and adapted to specific geological conditions. This makes it relevant for both oil recovery and dedicated CO₂ storage.

Foam technology combines CO₂ with surfactants to form a stable foam that regulates the gas’s mobility in the reservoir. This improves both displacement efficiency and storage capacity. By using foam in CO₂ injection processes, unwanted flow through the reservoir can be reduced. This increases oil displacement and stores larger amounts of CO₂ permanently. Foam technology provides economic incentives for the industry by combining increased oil production with cost-effective CO₂ storage, while enabling carbon-negative recovery processes. Early use of foam in EOR processes has proven crucial to maximizing both oil recovery and CO₂ storage. This gives the technology’s application unique value in CCUS strategies.

The power and value of high-quality research

Although CO₂-EOR has not been commercially implemented on the Norwegian continental shelf, research in this area has led to invaluable knowledge that now strengthens efforts in CO₂ storage.

Among the most important lessons are:

Fluid properties: Studies have revealed how CO₂ behaves in the subsurface, including solubility in water, injectivity, and flow characteristics in the reservoir.
Reservoir simulation: Modeling of CO₂ flow has improved our understanding of how the gas can be moved and stored safely. Projects using CO₂ foam contributed to developing better numerical models.
Materials technology: Research has identified and addressed challenges related to corrosion, which is crucial for both EOR and pure CO₂ storage.

Furthermore, Norwegian research institutions such as SINTEF have documented that between 70-100% of injected CO₂ remains stored in the reservoir after an EOR cycle. This indicates that the technology can not only contribute to increased oil recovery, but also to permanent CO₂ storage – a double benefit in the fight against climate change.

EOR’s evolution – From production to sustainability

Today, the focus in the Norwegian oil and gas industry is on safe and long-term CO₂ storage in aquifers and depleted fields. At the same time, several European initiatives have stipulated that CO₂ that is captured and transported should only be used for storage and not for oil recovery.

This shift reflects a global effort to reduce greenhouse gas emissions, and Norwegian actors are leading the way in developing infrastructure and value chains for CO₂ storage. EOR has thus become less relevant as a strategy, but the technologies and knowledge developed through EOR research live on in today’s CCS projects.

Standing on the shoulders of giants – Advancing CCS with the legacy of EOR

Although CLIMIT no longer prioritizes EOR in its project portfolio, it is important to recognize the value of the work that has been done. EOR projects have not only shown us the potential for increased recovery, but have also laid the foundation for today’s successes in CO₂ storage.

Through EOR research, we have gained a better understanding of subsurface dynamics, developed new technological solutions, and established robust models for how CO₂ can be used and stored. This knowledge has strengthened Norway’s position as a global leader in CCS and provides us with a solid foundation for future climate work.

EOR has shown us that the path to sustainability is not always straightforward, but that even technologies that have lost their commercial relevance can provide us with valuable tools to meet tomorrow’s challenges.

5.2.3 Further work on CO₂ reservoir and caprocks

Improved reservoir characterization: Continue the development of more accurate and efficient methods to characterize reservoirs, including the use of advanced geophysics, laboratory experiments, and numerical modeling. Focus on reducing uncertainty in estimates of storage capacity and flow properties.
Increased understanding of caprock behavior: Research on the long-term behavior of caprocks under the influence of CO₂ injection, including studies of mechanical and geochemical changes, as well as the potential for micro-leakages and fractures.
Modeling of geochemical reactions: Develop more sophisticated models that simulate geochemical reactions between CO₂, formation water, and rock, to predict long-term effects on the reservoir and caprock, and assess the potential for mineralization and changes in porosity and permeability.
Integrated risk assessment: Develop integrated models that combine reservoir characterization, caprock analysis, and geochemical modeling to provide a comprehensive risk assessment for CO₂ storage and identify potential challenges early on.

5.2.4 Conclusion

Understanding the reservoir and caprock is fundamental for safe and effective CO₂ storage. Through the CLIMIT program, significant progress has been made in characterizing reservoirs, evaluating caprock integrity, and modeling geochemical reactions. Further work is needed to improve the accuracy of models, reduce uncertainty, and optimize the CO₂ storage process. Continuous research and innovation in reservoir and caprock will be crucial to implementing CO₂ storage on a large scale and contributing to achieving climate goals.

5.3 CLIMIT program category – Monitoring and simulation

To ensure effective and secure CO₂ storage, it is essential to monitor the behavior of CO₂ in the subsurface and predict its long-term migration. Monitoring and simulation are important tools to verify storage security, optimize injection strategies, and manage potential risks. CLIMIT supports research that addresses these challenges within the program category of monitoring and simulation.

5.3.1 Challenges

Development of effective monitoring methods: It is necessary to develop reliable and cost-effective methods to monitor the spread and behavior of CO₂ in the reservoir over time. This includes detecting potential leaks, monitoring pressure development, and tracking CO₂ migration.
Accurate simulation of CO₂ migration: To predict the long-term behavior of CO₂ in the reservoir and assess the risk of leakage, accurate simulation models that take into account complex factors such as reservoir properties, geochemical reactions, and pressure changes are needed.
Data collection and analysis: Effective monitoring and simulation require the collection and analysis of large amounts of data from various sources, such as seismic surveys, well data, and geochemical analyses. It is important to develop methods to integrate and interpret this data to get a holistic picture of CO₂ storage.
Uncertainty management: Uncertainty in data and models can affect the accuracy of simulations and risk assessments. It is important to develop methods to quantify and manage uncertainty in monitoring and simulation.

5.3.2 The status on monitoring and simulation research

Several CLIMIT-funded projects have worked to improve the monitoring and simulation of CO₂ storage and developed solutions to address the challenges:

5.3.2.1 The Svelvik projects – Innovative monitoring for safe CO₂ storage

With a growing global focus on carbon capture and storage, Norway has established itself as a key player in the development of safe and effective solutions for CO₂ storage. SINTEF’s Svelvik projects are a good example of this commitment. In the period 2009-2019, support from CLIMIT triggered the realization of three distinct CCS projects in Svelvik, all of which have contributed to improving monitoring procedures and increasing understanding of CO₂ movements in the subsurface. This work is crucial for future CO₂ storage initiatives with safe storage.

*Drone photo (UiO) showing the Svelvik CO*₂ *Field Lab and position of the most important facilities.* Photo: UiO

Establishing a groundbreaking field laboratory

In 2009, the project “CO₂ Field Laboratory for Monitoring and Safety Assessment” started. The goal was ambitious: to develop monitoring procedures that ensure that unwanted CO₂ movements are detected early in any CO₂ storage, so that necessary measures can be implemented quickly and efficiently.

The project included a field trial in Svelvik, where two controlled injections of CO₂ were to be carried out at different depths in the subsurface. The focus was to monitor the movement of the injected CO₂ using several advanced techniques.

Phase 1: Conducting geophysical surveys and a test drilling to map the geological conditions. This was essential to confirm the suitability of the area for the planned investigations in the next phase.
Phase 2: Carrying out injection and monitoring trials. In 2011, a shallow injection was carried out by drilling an inclined well down to approx. 25 meters deep, where CO₂ was injected. Above the injection site, any leaks to the surface were carefully studied.

Although the deep injection was not carried out due to lack of industry support and less optimal geological conditions than expected, the project laid the foundation for future research. SINTEF has since worked to integrate the field laboratory into European collaborative projects and has received funding through ECCSEL for further development and use of the facility.

International collaboration for advanced CO₂ monitoring

In 2013, an ambitious collaborative project was launched. The project, called “Joint Inversion and Petrophysical Characterization for Improved CO₂ Monitoring at Ketzin and Svelvik”, aimed to improve understanding of geological CO₂ storage and develop more effective monitoring methods.

This project united the expertise of the GeoForschungs-Zentrum Potsdam (GFZ) in Germany and SINTEF in Norway, and combined methodologies from the CO₂ sites Ketzin and Svelvik. The central research tasks were:

Integration of monitoring methods: Combining GFZ’s successful use of Electromagnetic Resistivity Tomography (ERT) at Ketzin with SINTEF’s advanced Full Waveform Inversion (FWI) and joint inversion codes.
Advanced data analysis: Applying 3D/4D FWI and joint FWI-ERT inversions to existing and new data from Ketzin, and optimizing these methods for upcoming repeat measurements under the German COMPLETE project.
Method validation: Comparing and evaluating methods and results from individual and joint inversions to identify the most effective monitoring strategies.
Petrophysical characterization: Analyzing core samples of caprock and reservoir to better understand the properties of the rocks, with results that were also integrated into the joint inversion.

Through this international collaboration, the imaging of the CO₂ plume and the quantification of injected CO₂ at the Ketzin pilot plant were significantly improved. The project leveraged the experience from Svelvik to promote technological development that will be important for future CO₂ storage projects.

Pioneering work with fiber optic sensor technologies

In 2019, a new and innovative project was carried out with a focus on modern sensor technologies. The aim was to collect data from fiber optic cables during the Pre-ACT campaign in October 2019.

The research focused on the use of fiber optic sensor systems as a potential monitoring solution for CO₂ storage:

Distributed Acoustic Sensing (DAS)
Distributed Strain Sensing (DSS)
Distributed Temperature Sensing (DTS)

By comparing data from these fiber optic measurements with traditional methods, the researchers wanted to evaluate the effectiveness and precision of the new technologies. The injection tests in the autumn of 2019 at the Svelvik CO₂ Field Lab provided a unique opportunity for this.

The collected data was carefully quality controlled and securely stored. The aim is for this data to form the basis for a future KPN application, which will enable further analysis and comparison with conventional seismic data collected by the Pre-ACT project.

Significance of the Svelvik Projects

One of the most important contributions from the Svelvik projects is the development and testing of new monitoring methods. Through practical field trials, the projects have:

Tested advanced geophysical techniques: By integrating methods such as Electromagnetic Resistivity Tomography (ERT) and Full Waveform Inversion (FWI), the researchers have improved the ability to image and quantify the CO₂ plume in the subsurface.
Explored fiber optic sensor technologies: The use of Distributed Acoustic Sensing (DAS), Distributed Strain Sensing (DSS), and Distributed Temperature Sensing (DTS) has shown the potential for continuous and high-resolution monitoring of CO₂ movements.

5.3.2.2 The H-NET projects – Innovative seismic monitoring for safe CO₂ storage

Through several phases from 2018 to the present day, these projects have focused on developing and demonstrating cost-effective monitoring technologies within the framework of the Norwegian storage regulations, with particular emphasis on seismic monitoring of CO₂ storage in the Horda platform region.

Establishing a basis for seismic monitoring

In 2018, the Smeaheia Natural Seismicity Network (SNS-Net) project started. Equinor was the project manager, with partners NORSAR, Shell, and TotalEnergies. The background for the project was Equinor’s desire to demonstrate cost-effective monitoring technologies within the Norwegian storage regulations. Since the start of CO₂ storage at Sleipner in 1996, Equinor has been a pioneer in CCS technology, and NORSAR, with its leading international position in the application and interpretation of microseismic information, was a key partner.

Kystlandskap med hav, holmer og vegetasjon sammen med en liten landbasert lyttestasjon som ser ut som to paneler og en liten boks. Foto — Real-time data collection Photo: hordanet.no

The project aimed to investigate solutions for seismic instrumentation that were sufficient and cost-effective to establish the necessary background seismicity level in the Smeaheia area. This included assessing both land-based and seabed solutions, with a focus on optimizing station geometry and reducing noise. By establishing a monitoring solution that could detect background seismicity, it was desired to be able to assess any changes in the stress field caused by CO₂ injection. This would ensure that the monitoring solution was adapted to the requirements in the Norwegian storage regulations and contribute to documenting the safe storage of CO₂.

Further development and implementation of monitoring technology

In 2019, work continued with the H-Net project. Equinor was the applicant, with the same partners as before. As the operator for the full-scale CCS project Northern Lights, together with Shell and Total, Equinor wanted to demonstrate cost-effective monitoring technologies. The project built on the findings from SNS-Net and previous CLIMIT projects to mature the technology around microseismic monitoring.

Changes in the storage location from Smeaheia to Aurora required adjustments in the monitoring strategy. The project was divided into several phases, where phase 1 was already completed. In phase 2, the concepts were continued with the implementation of instrumentation on land and the use of permanent seismic nodes (PRM) on the seabed, as well as the initiation of data collection and reporting. The goal was to establish the world’s first continuous monitoring of an offshore CO₂ storage. By balancing costs and quality, it was desired to show that large-scale CO₂ storage is feasible elsewhere as well. The project sought to meet the requirements in the Norwegian storage regulations by implementing best practices for monitoring techniques.

Preparation for injection and extended monitoring

In 2021, phase 3 of the H-Net project was initiated. Equinor was the applicant, with partners Shell, TotalEnergies, Northern Lights JV, NORSAR, and the University of Bergen. The project focused on pre-operational monitoring before the planned start of CO₂ injection in 2024. The purpose was to build a solid understanding of natural seismicity as a basis for assessing possible induced seismicity during the injection period.

The continuation of previous phases included operation of the land-based seismic array HNAR on Holsnøy and testing of new seabed seismometers. The main activities in the project included routine operation of the HNAR seismic, testing of offshore deployment of seabed seismometers, advanced data analysis and interpretation research, as well as risk assessment and data integration. The goal was to establish the world’s first continuous microseismic monitoring array for an offshore CO₂ storage project, ensure safe storage, and reduce uncertainty related to long-term storage of CO₂. The project would also meet regulatory requirements by implementing advanced monitoring technologies.

The HNAR array has matured to be directly funded by the industry. This reflects confidence in the project’s relevance and value, and is considered a success for the CLIMIT program.

Seismicity in the Horda platform and surrounding areas (southwest coast of Norway). Sorce: Zarifi et al. 2022.

The importance of increased partner collaboration

Through the first three phases of the H-Net projects, there has been a significant increase in the number and diversity of partners. Several new players have joined, including specialized technology companies and academic institutions. This expansion of the partnership has brought in specialized expertise in fiber optic technology, geophysical modeling, and seabed seismic.

The involvement of the University of Bergen has promoted research-driven innovation and contributed to knowledge development. This strengthens collaboration between industry and academia. This is crucial to drive technological progress. The fact that international companies such as Shell and TotalEnergies are involved expands the project’s global network and provides access to advanced technology. In phase 3, Northern Lights JV joined as a new partner, which further strengthened the link to the Longship project.

Increased partnership in this series of projects has important implications. Firstly, it accelerates technology development by pooling resources and broad expertise. This can contribute to faster maturation of new monitoring technologies. Secondly, it provides better risk management; a larger partner network enables more comprehensive risk assessments and implementation of robust monitoring solutions. Furthermore, it promotes best practices, as collaboration facilitates knowledge sharing and the establishment of international standards for CO₂ storage and monitoring. Finally, it strengthens Norway’s position as a player in CCS and seismic monitoring, which can attract global interest and investment.

The monitoring journey advances: Phase 4 application under review

An application for funding for phase 4 was received in October 2024, and is currently being processed by CLIMIT. NORSAR is now the applicant, and the partner list has been further expanded.

5.3.2.3 The ACT projects – Innovative monitoring for safe CO₂ storage

Effective monitoring of CO₂ storage sites has been essential for safe and permanent storage. Among the prominent projects that have contributed to the development of advanced monitoring systems are DigiMon, SENSE, and SHARP, all part of the ACT program (Accelerating CCS Technologies).

DigiMon: Digital Monitoring of CO₂ storage projects

The DigiMon project aimed to accelerate the implementation of CCS by developing and demonstrating a cost-effective, flexible, and intelligent digital monitoring and alert system. The project built on results from various technical and social science studies carried out by the consortium’s partners, which included instrument suppliers, research institutions, and operators such as Equinor and Repsol.

By integrating a wide range of technologies for measurement, monitoring, and verification (MMV) of CO₂ storage, such as fiber optic sensor technology (DxS), seismic point sensors, and gravimetry, combined with ethernet-based digital communication and real-time web-based data processing software, DigiMon offered a new and cost-effective solution for early warning and monitoring of CO₂ reservoirs and underground barriers.

The project focused on monitoring CO₂ migration in the reservoir using passive geophysical measurements of changes in saturation and pressure, as well as monitoring well integrity with downhole sensors. In addition, work was done on monitoring stress and early detection of CO₂ leakage anomalies.

Through experimental laboratory studies, collection of field test data, modeling, and optimization, DigiMon contributed to the improvement of individual system components and the development of workflows for processing and interpreting monitoring data. A strong focus on interdisciplinarity between technical disciplines and social sciences characterized the research, and unique methods were also developed to assess CCS technologies based on social acceptance and utility value.

SENSE: Ensuring the integrity of CO₂ storage sites through surface monitoring

The SENSE project was based on the use of monitoring technology and methods to link surface uplift to hydromechanical processes in the reservoir. By developing measurement techniques that captured small movements on a millimeter scale on land and the seabed, the project performed measurements in four different case studies. These movements were linked to reservoir pressure through geomechanical models and inversion methods, with the aim of concluding whether CO₂ in the reservoir was moving as expected or if something abnormal was happening, so that an alarm signal could be given to the operator.

The four case studies included:

Hatfield Moors in England, where the relationship between pressure changes in a sandstone reservoir used for natural gas storage and surface movements was analyzed.
In Salah CO₂ storage site in Algeria, where post-injection data was studied to see how the surface reacted after injection was stopped.
Boknis Eck offshore in Germany, where full-scale experiments were carried out and seabed movements were measured as a result of injection or simulated uplift.
Gulf of Mexico, where geological and geophysical data were used for various CO₂ injection scenarios, and movement on the seabed was estimated through geomechanical modeling.

Seks ulike ovaler i en sirkel som viser ulike deler av prosjektet. Illustrasjon. — Activities and methods used in the SENSE project. Illustration: NGI

SENSE brought together 14 partners from 9 countries, including Equinor, NGI, Quad Geometrics, and the University of Oslo from Norway, as well as international institutions from Germany, UK, France, Spain, USA, Japan, Australia, and South Korea. The project helped to test and validate techniques for continuous measurement of ground movements, develop methodology to link these measurements to mechanical events in the reservoir, and offer operators cost-effective methods for monitoring and safe storage of CO₂.

SHARP: Quantifying risk in CO₂ storage through stress data and geomechanical models

The SHARP project addressed three priority research areas to improve technologies needed for large-scale CO₂ storage. Geomechanical response to CO₂ injection represents a significant uncertainty in the assessment of storage sites, and SHARP aimed to reduce this uncertainty.

Through an interdisciplinary and international consortium with 16 partners from 5 countries, the project developed basin-scale geomechanical models that included tectonic stresses and the effects of post-glacial movements. Knowledge of the current stress field in the North Sea was improved by integrating earthquake catalogs and data on past earthquakes and fault movements. The project also quantified rock strength and identified fracture properties suitable for monitoring and risk assessment.

*The SHARP project team members visiting the Northern Lights facility at Øygarden (in the background) in May 2024. Photo: SHARP project / ACT-CCS*

SHARP is expected to have accelerated the maturation of several case studies in the North Sea and India, and contributed to scaling up storage prospects in saline aquifers such as Northern Lights in the Horda area and new prospects in the Greater Bunter Sandstone area. By developing technology for quantifying subsurface deformation and cost-effective risk management of CO₂ storage, the project provided effective tools to assess and manage the risk of leaks. Strategies for monitoring deformation and induced seismicity were communicated to operators and authorities to increase confidence in storage security.

Significance of the ACT projects for future CO₂ storage

DigiMon, SENSE, and SHARP have all promoted the development of cost-effective and advanced monitoring systems that are essential for safe and effective CO₂ storage. Through the integration of advanced technologies, development of new methods, and international collaboration, these projects have helped to reduce barriers to CCS implementation. They have ensured that storage takes place in a way that is acceptable to society, and strengthened confidence in CCS.

By focusing on both technical and social aspects, the projects have laid the foundation for future solutions that benefit the environment and society. Their contributions are important for achieving safe and effective CO₂ storage.

5.3.2.4 Distributed Seismic Monitoring for Geological CO₂ Storage (DemoDas)

Between 2016 and 2019, NORCE, in collaboration with NTNU and NORSAR, carried out a project to explore the use of DAS for monitoring geological CO₂ storage. DAS technology uses fiber optic cables as sensors to detect vibrations and seismic signals, and has the potential to become a cost-effective solution for long-term monitoring of CO₂ storage sites.

During the project, three prototypes of DAS instruments were developed and tested both in the laboratory and in the field. Field trials were carried out at the NTNU field laboratory in Trondheim and at the CaMi Field Research Station in Canada. Using fiber cables mounted on the surface and in wells, the DAS system could detect man-made tremors and seismic signals. Tests showed that signals could be captured over a length of 50 km of fiber cable, but challenges arose with signal interpretation, especially for long distances.

The project also included analyses of natural fractures and faults as potential leakage pathways for CO₂. Field studies in Mexico and Utah, USA, confirmed a clear link between fracture zones and CO₂ leakage. Although DAS could not be tested in full-scale injection scenarios during the project period, historical data, such as the 1989 North Sea blowout, were analyzed to understand gas migration in the stratigraphy above the reservoir.

Among the project’s main results was a better understanding of the potential of DAS technology to monitor geological processes and detect leaks. DAS proved to be a promising tool for permanent monitoring, but further development is needed to improve data analysis methods and interpretation accuracy. The project also contributed to the design phase of the ECCSEL Svelvik CO₂ Field Lab and laid the foundation for future research and international collaborations.

5.3.2.5 The HPC Projects for gigatonne CO₂ storage – Groundbreaking software for large-scale storage challenges

For CCS to contribute significantly to the reduction of greenhouse gas emissions and meet global emission targets by the middle of this century, storage capacity must be scaled up from today’s tens of millions of tons to billions of tons, i.e., gigatonne scale. Continental margins such as the Norwegian continental shelf are particularly well suited for CO₂ storage, and significant investments have been made in Norway, Australia, the USA, and elsewhere to stimulate large-scale CCS and establish a new industry in CO₂ transport and storage.

HPC simulation software for gigatonne storage challenges (Phase 1)

The project “HPC simulation software for the gigatonne storage challenge” aimed to develop a reservoir simulator with advanced functionality to simulate CO₂ storage on a gigatonne scale. A major bottleneck in today’s workflow was dynamic simulation of large-scale CO₂ injection with sufficient resolution and efficiency. Today’s reservoir simulators could not do this, and a reliable gigatonne reservoir simulator was needed to enable scaling up of CO₂ storage.

“A reservoir simulator can be used, among other things, to find out which reservoir is best suited for CO₂ storage, as well as whether CO₂ will remain in the reservoir if it is stored there. It is important that such simulators have undergone extensive testing so that industry can trust the results shown.”

In an interview with Gassnova on January 26, 2022, Sarah Gasda, research director at NORCE and project manager for the project, stated (translated from Norwegian)

The project built on close collaboration between NORCE, SINTEF, and Equinor, with a focus on developing the Open Porous Media (OPM) reservoir simulator as a dedicated simulator for CO₂ storage. The code development was based on concepts developed in collaboration between industry, research, and government, with participants such as the Norwegian Petroleum Directorate, CarbonNet in Australia, UT Austin Bureau of Economic Geology in the USA, and TNO in the Netherlands.

“It is important that this type of software is free and openly available. Anyone who wants to can see all the details of how mathematical models and calculation methods are implemented. This is not only important for building trust in the software, but also helps to accelerate technology development in this field.”

Atgeirr Flø Rasmussen, senior researcher at SINTEF, pointed out in the same interview the importance of open access (translated from Norwegian)

One of the most important deliverables was the demonstration of HPC performance on supercomputer infrastructure, including cloud-based computing. The simulation tool was made openly available and free of charge to the CCS community, with all necessary user documentation, including tutorials and demonstration videos.

“The advantage of OPM Flow being developed in an open framework is that various actors can contribute to the further development and improvement of the software. CO₂ storage is something we have to work on together, and the industry must be involved.”

Tor Harald Sandve, senior researcher at NORCE, added (translated from Norwegian)

The results from the project enabled operators to assess CO₂ storage more effectively and plan for large-scale field development on a gigatonne scale.

Ill.: Preliminary simulation study on the SPE11 benchmark case for CO₂ *storage, Olav Møyner, SINTEF*

HPC simulation software for gigatonne storage Challenges, Phase 2

Following the success of phase 1, work continued on the project in a second phase, with the aim of accelerating further development of HPC technology for CO₂ storage simulation. In phase 1, a crucial milestone was reached with the release and demonstration of the CO2STORE module in the OPM Flow simulator—a dedicated CO₂ storage option that is easy to use, accurate, and has high performance. The module was successfully used on a regional model of Smeaheia with several million cells.

In phase 2, it was necessary to further improve performance and stability to include dissolution processes and thermal effects in realistic field-scale simulations. The project also aimed to expand the applications to new topics, such as storage in depleted hydrocarbon fields, and to collaborate with other simulator groups to develop an international benchmark for simulating field-scale CO₂ injection.

“The results from this project will enable operators to assess CO₂ storage more effectively and plan for large-scale field development on a gigatonne scale.”

Kari-Lise Rørvik at Gassnova, stated in the same interview (translated from Norwegian)

Close collaboration with relevant user groups strengthened the project’s relevance. In phase 2, the group was expanded to include users from Denmark and the UK, in addition to the Netherlands, USA, and Norway. The goal was to deliver a dedicated CO₂ storage simulator that could become the preferred option for the CCS community.

Gigatonne CO₂ storage is an unproven concept, and a regional perspective is key to ensuring good utilization of infrastructure and storage resources. A particular challenge is modeling interaction with ongoing petroleum activities. A fast and reliable simulator, which was the goal of this project, could provide computational capacity that enabled large-scale simulation of gigatonne CO₂ storage.

A gigaton leap forward

Through the development of a dedicated and open reservoir simulator for CO₂ storage on a metric gigaton scale, these projects have addressed a critical bottleneck in scaling up CCS. By offering a tool capable of simulating large and complex reservoirs with high accuracy and efficiency, they enable the industry to plan and implement large-scale CO₂ storage.

The open availability of the simulator promotes collaboration and further development in the CCS field. This collaboration is essential to meet global climate challenges and realize the potential of CO₂ storage as an effective climate solution.

The projects have also helped build confidence in CO₂ storage technologies by ensuring that the tools used are transparent and thoroughly tested. This is crucial to ensure that decisions are based on reliable data and models. This is important for regulatory authorities, industry, and society in general.

5.3.2.5 Capacity of large-scale CO₂ storage in North Sea sloping aquifers from numerical simulation

Between 2013 and 2016, Uni Research AS led a project that focused on evaluating the capacity and risk of storing CO₂ in sloping aquifers in the North Sea. The project, funded by the CLIMIT program, had the main objective of developing best practices for numerical simulation of CO₂ storage in such formations. The work was carried out in collaboration with partners in Norway and Canada and included both the development of advanced simulation tools and analyses of geological data from relevant storage sites.

Research and methods

The project addressed several key issues related to large-scale CO₂ storage. One of the most important tasks was to simulate how CO₂ migrates and is trapped in sloping aquifers over long time scales. For this purpose, the project developed and compared different simulation models, including conventional compositional simulators and more simplified models based on vertical equilibrium.

Another important aspect was uncertainty analysis related to storage capacity, including the effects of caprock topography, the reservoir’s geomechanical properties, and boundary conditions. The project implemented statistical methods to reduce computation time and enable extensive sensitivity tests. For example, simulations of the Skade aquifer showed that pressure build-up can be a limiting factor, especially in shallower areas where the initial stress is lower.

The project also developed an improved equation of state for CO₂, which enabled more accurate modeling of the liquid phase and estimates of drying effects in the near-wellbore region. This was crucial to understanding how CO₂ affects the reservoir’s properties and migration patterns over time.

Significance and results

The results from the project have great significance for future CO₂ storage in the North Sea. The simulations have provided insight into how various geological parameters affect storage capacity and safety, and they have shown that key factors such as permeability and formation thickness have a major impact on injection strategies.

The project has also delivered tools for simulating geomechanical effects and vertical flow, which can be applied to relevant storage sites in Norway. This includes open-source software for such evaluations, which can be used by both academic and industrial actors.

Through the development of advanced numerical models and extensive uncertainty analyses, the project has contributed to improving understanding of CO₂ storage in sloping aquifers. The results lay the foundation for safer and more efficient storage operations and underscore the need to adapt injection strategies to local geological conditions.

5.3.2.6 Simulation and optimization of large-scale CO₂ injection at basin scale in the North Sea

Between 2015 and 2018, SINTEF led a research project that aimed to develop advanced simulation tools for large-scale injection and storage of CO₂ in saline aquifers in the North Sea. The project was funded by the CLIMIT program and carried out in collaboration with researchers from the University of Texas at Austin, who have extensive experience with natural CO₂ deposits as analogs for long-term storage.

Optimized injection scenario obtained by penalizing future leakage in Utsira North. The color scale used in snapshots of plume evolution refers to tons of CO₂ per lateral square meter. Illustration: SINTEF

Research and results

For CO₂ storage to play a central role in reducing European greenhouse gas emissions, storage activities must be scaled up significantly. This requires reliable estimates of storage capacity and a thorough understanding of the long-term behavior of injected CO₂, including the potential for leakage. Existing simulation tools, primarily developed for the oil and gas industry, have limited ability to address the challenges associated with CO₂ storage.

The project developed specialized mathematical models and simulation tools optimized for CO₂ storage. These tools provide faster and more accurate results compared to traditional 3D simulators. A particular focus was on methods for calculating parameter sensitivity, which is crucial for optimizing injection strategies and integrating monitoring data.

Key activities include

Analysis of storage capacity and optimal placement of injection points in large saline aquifers.
Collaboration with the University of Texas to use the Bravo Dome in New Mexico as an analog for long-term storage. This natural CO₂ deposit has been studied for decades and provides valuable insight into long-term processes.
Development and distribution of open-source code as part of the Matlab Reservoir Simulation Toolbox (MRST). This tool enables researchers and industry to simulate complex storage scenarios with a high degree of accuracy.

Significance and implications

The project has helped to resolve key issues related to injecting hundreds of megatons of CO₂ into large aquifers. The tools and workflows developed in the project provide new opportunities to:

Evaluate storage capacity at the basin scale and optimize the utilization of pore volume.
Reduce the risk of leakage through improved modeling and understanding of pressure and flow response.
Implement cost-effective strategies for large-scale CO₂ storage with a focus on long-term safety.

By integrating data from natural CO₂ fields and advanced numerical methods, the project has also provided valuable knowledge for future storage projects, especially in the North Sea.

5.3.2.7 Monitoring and control of pore pressure for safe and effective CO₂ storage

The Pre-ACT project, led by SINTEF in collaboration with international partners, was carried out between 2017 and 2020 with the aim of improving monitoring and management of pore pressure in reservoirs for safe and effective CO₂ storage. The project addressed challenges related to capacity, costs, and trust, which are crucial for large-scale deployment of CCS.

Through the project, pressure-driven methods and recommendations, known as Pre-ACT protocols, were developed for cost-effective reservoir monitoring. These helped operators maximize CO₂ storage capacity and translate monitoring data into corrective actions quickly and efficiently. The project included collaboration with key industry partners such as Statoil, Shell, TOTAL, and TAQA, which ensured the relevance and practical application of the methodologies.

Results

Modeling of pressure build-up and distribution: Development and demonstration of methods for modeling pressure in reservoirs, including uncertainty studies on the Smeaheia field.
New monitoring techniques: Quantitative methods for measuring pressure and saturation that include uncertainty analyses.
Compliance tools: Development of a model-monitoring loop for assessing reservoir status.
Demonstrations and field studies: Included tests at the Svelvik CO₂ Field Lab, which was reopened and used for the first CO₂ injection for data generation.
Decision support: Recommendations for optimizing data acquisition and developing protocols for decision-making.

The project also organized several stakeholder meetings, including in Trondheim and Brussels, to communicate the project’s relevance to politicians, researchers, and industry partners.

Achievements

Pre-ACT made significant contributions to CCS technology through new methods for monitoring and managing reservoir pressure. These methods help operators ensure safe and permanent CO₂ storage. The tools developed included methods for optimizing data acquisition and compliance protocols, as well as instrumentation and fieldwork at the Svelvik laboratory.

5.3.2.8 CO₂ permeability along fragmented shale interfaces

Between 2016 and 2019, SINTEF, in collaboration with NTNU, IRIS, and Los Alamos National Laboratory in the USA, carried out a research project to understand how drilling operations affect the integrity of wells in CO₂ storage projects. The project, supported by the Research Council’s CLIMIT program, focused on how fragmentation of shale during drilling can lead to weaknesses in well sealing and possible CO₂ leakage.

Research and innovations

The project investigated in detail how fragmentation of shale affects cement placement and the long-term integrity of the well seal. The work was divided into three main phases:

Mapping the extent of damage: Shale samples were subjected to mechanical and chemical influences to simulate the effect of the drilling process. Afterwards, cement was injected to evaluate the quality of the seal.
Studies of cement placement: A specially developed X-ray transparent cell was used to investigate cement placement in fragmented shale samples under pressure and controlled flow conditions. This made it possible to understand how cement interacts with different shale structures.
Evaluation of surface properties: The last phase focused on how the properties of the shale surface affect the cement’s ability to create a tight seal.

The project showed that cement placement can be inadequate under certain conditions, especially when the fragmentation of shale is extensive. This can lead to poor zonal isolation and risk of leakage.

Significance and implications

The results from the project have provided valuable insight into how drilling operations can be optimized to minimize fragmentation and improve the quality of cement placement. This includes:

Optimizing drilling parameters such as circulation rate, rotation speed, and drilling angle to reduce fragmentation.
Developing improved cement formulations that can better seal against fragmented shale surfaces.
A new framework for predicting leakage risk in wells that penetrate CO₂ storage reservoirs.

Conclusion

The project has strengthened understanding of the interaction between drilling operations, fragmentation of shale, and cement placement. This knowledge is crucial to ensure safe and effective CO₂ storage, especially in wells where fragmentation can be a problem. The results help to reduce the risk of leakage and increase confidence in CO₂ storage.

5.3.2.9 Environmental impacts of leakage from sub-seabed CO₂ storage

Between 2016 and 2019, NTNU led a research project that investigated the environmental impacts of diffuse leakage from CO₂ storage beneath the seabed. The project, funded by the CLIMIT program, used advanced laboratory experiments to simulate seabed conditions and assess how such leaks can affect geochemistry, metals in sediments, microbial communities, and organisms in deep-sea environments.

Research and results

The project utilized a unique pressure tank, called Karl Erik TiTank, which allowed experiments under pressure conditions equivalent to 300 meters depth. This made it possible to simulate realistic conditions for CO₂ leaks and their effects.

Mobilization of metals

Experiments showed that CO₂ exposure led to significant mobilization of metals such as arsenic (As) and cadmium (Cd), especially in sediments with specific geological properties. Lower pH increased mobilization, and transformations between different chemical fractions of metals in the sediments were also observed. Calcareous sediments from the Trondheim Fjord showed greater dissolution than sediments from the Barents Sea.

Effect on macrofauna and microbial activity

Experiments with the deep-sea organism Astarte sp. showed no lethal effects or bioaccumulation of toxic elements at pH 7. However, CO₂ leakage affected the bacterial composition in the sediments, with changes in species diversity and biochemical cycles that can have long-term consequences.

Organic carbon and microbial carbon turnover

The results suggested changes in the loading of organic carbon during CO₂ exposure, which can affect microbial degradation and carbon storage in the marine environment.

Modeling of leakage effects

Numerical models such as TOUGHREACT and BROM were used to simulate chemical profiles and hydrodynamic effects of CO₂ leakage. These models confirmed that pH and dissolved iron and calcium can be good indicators of leakage, and that the effects of a short-term leak can be traced for several days in a limited area around the leak point.

Significance and implications

The results provide new insights into how CO₂ leakage affects sediment chemistry, metal mobilization, and biological activity in marine systems. This is important for understanding the risks and consequences of CO₂ storage beneath the seabed. The project has also provided recommendations for better monitoring methods and compliance with regulations such as OSPAR and the London Protocol.

The project resulted in several scientific articles and master’s theses, as well as dissemination to decision-makers and industry. The results are relevant for the planning and operation of CO₂ storage sites such as Sleipner and Snøhvit, and provide a scientific basis for the development of more effective monitoring strategies.

5.3.2.10 Bayesian monitoring design (BayMoDe)

Between 2016 and 2020, the University of Bergen led a research project that focused on developing effective monitoring programs for CO₂ storage beneath the seabed. The project, funded by the CLIMIT program, used Bayesian statistics to design monitoring programs that can detect leaks or irregularities in the marine environment, while reducing false alarms.

Research and results

BayMoDe addressed an important challenge in CO₂ storage: distinguishing the signals from a potential leak from the natural variation in the marine environment, such as seasonal changes and acidification. The methods developed include:

A probabilistic framework for analyzing environmental data and predicting leakage footprints. This framework combines environmental statistics with predictions based on the properties of possible leak sources.
Machine learning algorithms to classify signals and reduce uncertainty in monitoring data.
A structure to increase “belief” in a leak based on multiple indications, and to avoid false alarms by ensuring that individual data deviations do not automatically trigger extensive measures.

The project collaborated with international partners, including Plymouth Marine Laboratory and Heriot-Watt University, and contributed to the Horizon2020 project STEMM-CCS. A release experiment in the Goldeneye area off Scotland in 2019 provided valuable data that was used in the development of environmental monitoring tools.

En fjernstyrt undervannsfarkost (AUV) sendes ned for å undersøke havbunnen. Foto. — A remotely controlled underwater vehicle (AUV) used to investigate the seabed. Photo: Doug Connelly, National Oceanography Center, UK.

Significance and implications

The BayMoDe project has contributed to increased Norwegian activity in environmental monitoring for CO₂ storage and laid the foundation for further research through the establishment of the ACTOM project. The results have also strengthened Norwegian expertise in documentation and monitoring, with an approach that can be used in all types of monitoring programs.

By reducing uncertainty and improving monitoring procedures, BayMoDe contributes to increased confidence in CO₂ storage as a safe and effective climate solution. The project has published over 10 peer-reviewed articles and trained a PhD candidate in applied mathematics specializing in machine learning for environmental monitoring.

5.3.2.11 Induced-seismicity geomechanics for controlled CO₂ storage in the North Sea (IGCCS)

Between 2017 and 2020, the IGCCS project was carried out to improve understanding of induced seismicity and geomechanics related to CO₂ storage in the North Sea. The project, led by NGI, brought together international partners from Europe and Australia, including NORSAR, the University of Oslo, the National Oceanography Centre, and the Commonwealth Scientific and Industrial Research Organization. The goal was to link geomechanical effects to micro-seismic monitoring and develop methods to ensure safe and effective CO₂ storage.

Research and innovations

The project investigated geomechanical and seismic processes through advanced laboratory tests, numerical simulations, and field-based studies. Representative geology from the North Sea was defined as the basis for all tests and simulations. The work included:

Laboratory tests: 16 triaxial tests that measured acoustic emission (AE) and geomechanical properties from rock samples. This included samples from the North Sea and analog materials. The tests revealed how fluid saturation and temperature influences alter rock behavior.
Numerical simulations: Development of models for poro-thermoelastic processes and fracture propagation, which showed how CO₂ injection affects stress and strain distribution in the reservoirs.
Microseismic data: Generation of synthetic data to understand the mechanisms behind slow seismicity, with a focus on similarities between natural and induced earthquakes.

The results showed that temperature changes from cold CO₂ injection can have a significant effect on deep layers and caprocks. Microseismic signals were related to specific stresses and fracture processes, which contributes to better monitoring and risk analysis.

Significance and implications

IGCCS has helped to build a solid knowledge base for future CO₂ storage projects. The project has:

Updated industrial databases with new experimental data on geomechanical properties.
Recommended specialized laboratory tests and advanced simulation methods to handle thermal effects in caprocks, especially relevant for deep storage sites such as the Aurora project in the North Sea.
Developed new methods to identify and control potentially hazardous seismic events during CO₂ injection.

Conclusion

IGCCS has strengthened understanding of how induced seismicity and geomechanics can be used to ensure safe and effective CO₂ storage. The project’s results support the development of commercial storage projects in the North Sea and lay the foundation for further research in monitoring and risk analysis of CO₂ storage sites.

5.3.2.12 Prediction of CO₂ leakage from reservoirs during large-scale storage

Between 2018 and 2021, the Institute for Energy Technology (IFE) carried out a research project that focused on understanding the formation and significance of pipe structures (also known as “chimneys”) in sedimentary basins for safe CO₂ storage. The project investigated how these structures, which can act as leakage pathways, are formed and affect storage integrity in CO₂ repositories such as the Utsira Formation in the North Sea.

Top of Utsira Formation. The black polygons indicate areas which may be favorable for CO₂ storage. Norwegian Offshore Directorate

Research and results

Pipe structures are vertical channels in the caprock that are often associated with previously high pore pressure in reservoirs. These structures can be formed by viscous deformations or hydraulic fracturing of the sediments, and they are common in sedimentary basins globally.

The project used advanced numerical models and geological data from the North Sea to simulate the formation and evolution of pipe structures. The results showed that:

Pipe structures can form under realistic conditions for CO₂ storage.
The presence of pipe structures can significantly increase the risk of CO₂ leakage.
Glacial processes and overpressure from sedimentary layers can contribute to the formation of pipe structures.

Significance and recommendations

Monitoring of the seabed: The project recommends that the seabed above pipe structures be monitored, especially where they are located near CO₂ repositories, to ensure that they do not pose a leakage threat.
Improved understanding of geological processes: The project has contributed new insights into how glacial processes and overpressure from sedimentary layers contribute to the formation of pipe structures.
Open source: Numerical codes developed in the project have been made available as open source, which supports further research and industrial application.

The project has strengthened understanding of CO₂ storage integrity by mapping risk factors related to pipe structures and proposing strategies for monitoring and risk management.

5.3.2.13 Use of noble gas signatures in monitoring systems for offshore CO₂ storage

Between 2018 and 2022, the University of Oslo led the ICO2P project, a research project that explored the use of noble gases to monitor CO₂ storage sites. The project, funded by the CLIMIT program, combined innovative technology and advanced geochemical analyses to develop cost-effective and robust methods to verify the safety of CO₂ storage in the long term.

Anja Sundal. Foto. — Anja Sundal, project manager.

Research and innovation

ICO2P introduced a new approach to monitoring by exploiting the unique isotopic signatures of noble gases. Using a portable mass spectrometer, miniRUEDI, the researchers collected real-time data on the noble gas content in gas production and CO₂ injection lines. This tool allowed detailed analyses of gas composition, which provides precise information on source-specific properties of injected and natural gas.

The project included extensive field studies at CO₂ capture plants such as the Technology Centre Mongstad and Melkøya (Snøhvit), as well as test injections at the Svelvik field laboratory. The results showed that noble gases can be used to trace the origin of the gas and distinguish between anthropogenic and natural sources. The project also documented how injected CO₂ changes signature through interaction with geological reservoirs over time.

Results and significance

ICO2P has demonstrated how noble gas data can improve the reliability of CO₂ storage monitoring by enabling:

Accurate identification of leak sources by differentiating between anthropogenic and natural gases.
Cost reduction by utilizing inherent noble gas signatures instead of artificially added tracers.
Improved understanding of gas behavior in geological reservoirs, which increases storage safety.

In the summer of 2020, the project collected sediment samples from the seabed near the Aurora CO₂ storage site, and the analysis results contribute to the design of specific monitoring schemes for different CO₂ sources. This research is not only relevant for the Norwegian continental shelf, but can also be applied globally to support the development of CCS as a key tool for climate mitigation.

Conclusion

The ICO2P project (film) has laid the foundation for a new generation of monitoring methods that combine innovative technology with geochemical expertise. The results strengthen confidence in CO₂ storage as a safe and effective solution.

5.3.2.14 Techniques for identifying safe CO₂ storage

The COTEC project (2019–2023), led by the University of Oslo, was an interdisciplinary research project that used a natural field laboratory in Utah, USA, to study the migration and storage of CO₂ in areas with well-mapped geology. The project has been highly relevant for quality assurance of CO₂ storage initiatives on the Norwegian continental shelf, especially in areas such as the Smeaheia and Johansen prospects.

COTEC brought together Norwegian universities and research institutions (UiO, UNIS, NGI, NORSAR) with four American universities, and the project also included a comprehensive education program with PhD and Postdoc positions as well as MSc students.

The COTEC project mainly focused on the Little Grand Wash Fault south of Green River, Utah (yellow square), in the vicinity of the San Rafael Swell Monocline (Modified from Zuchuat et al. 2019a). | See large map 1000px.

Results

Geological analysis of CO₂ leakage mechanisms: The study of natural leaks in Utah provided insight into how geological and geomechanical conditions, such as fracture zones and permeable rocks, control the flow of CO₂ through tight rock layers.
Seismic data acquisition and analysis: The project developed methods to identify low-velocity zones, which are linked to highly permeable areas with increased CO₂ emissions from the ground. These zones were mapped using 2D seismic and high-resolution studies.
Modeling of CO₂ flow: 3D models were used to simulate geophysical signatures of CO₂ flow along fault zones. These models help to assess potential risks and design measures for commercial storage projects.
Knowledge sharing: Results from the project were presented at seminars and conferences, and all peer-reviewed articles were published as open access to reach both research communities and industry players.

Achieved effects

COTEC has contributed to a better understanding of the complexity of fracture zones and the risks associated with CO₂ storage. The findings are of great importance for the development of safe and effective storage methods, especially for projects in the North Sea. The project demonstrated how natural leakage sites can serve as analogs for CO₂ storage beneath the seabed, which provides valuable knowledge to reduce risk in future projects.

5.3.2.15 Accelerating CSEM technology for efficient and quantitative CO₂ monitoring

SINTEF started a project in 2019 that sought to develop and demonstrate cost-effective methods for monitoring CO₂ storage using Controlled Source Electro-Magnetics (CSEM). The project, funded by the CLIMIT program, addresses the need for more affordable and accurate monitoring tools to achieve safe and reliable geological storage of CO₂, in line with national and international requirements.

Research and methods

CSEM technology offers a complement to traditional seismic surveys by measuring resistivity and anisotropy in the subsurface. This provides important additional information that can improve the interpretation of pressure and saturation changes caused by CO₂ injection, thereby reducing uncertainties in the data basis. The project focuses on developing:

Optimal design of surveys and interpretation of time-lapse data.
Efficient simulation of how infrastructure affects CSEM data.
Integration of CSEM with other geophysical data for improved interpretation.

By using realistic offshore case studies from the Norwegian continental shelf, including Smeaheia, the project also investigates how CSEM can be combined with seismic data to achieve higher precision in monitoring. The project also includes the development of methods to address the lower resolution of CSEM compared to seismic, and how this affects temporal and spatial surveys.

The primary objective of this project is to develop and apply a cost-efficient CO₂ monitoring concept using time-lapse CSEM and demonstrate its readiness for the future Norwegian large-scale CO₂ storage project (Smeaheia/Johansen). Illustration: SINTEF.

Results and significance

During the project’s first year, several articles have been published, including studies that explore the potential for CSEM at Smeaheia and how resistivity can be used as an indicator of saturation changes during CO₂ injection. These results have been disseminated through conference presentations, extended abstracts, and webinars, which has increased awareness of the role of CSEM technology in CO₂ monitoring.

The project contributes to the development of monitoring strategies that are not only more cost-effective, but also provide increased safety and better public acceptance of CCS technology. By reducing reliance on expensive and extensive seismic surveys, CSEM offers a sustainable solution for large-scale CO₂ storage.

The project shows how innovative use of CSEM can help improve quantitative characterization of storage complexes and optimize geophysical surveys for CO₂ storage. By focusing on the combination of CSEM and seismic, and developing new methods for interpretation and simulation, the project lays the foundation for more efficient and safe solutions for future storage projects in Norway and internationally.

5.3.2.16 CSEM for monitoring CO₂ storage

SINTEF, in collaboration with Allton and TotalEnergies, is leading the ongoing project “COSMOS” to develop and implement new monitoring technologies for CO₂ storage. The project investigates how marine Controlled Source Electromagnetic (CSEM) technologies can be used as a cost-effective alternative to traditional seismic surveys. This is particularly relevant for the safe storage of CO₂ according to international rules and standards.

CSEM technology was originally developed for oil and gas exploration, but has shown potential for CO₂ storage. The technique exploits the contrast between the resistance of injected CO₂ and the saline pore fluid in the reservoir. COSMOS focuses on evaluating how CSEM can monitor the CO₂ plume in the reservoir and detect leaks. The project was initially linked to the Aurora storage complex, which is part of the Longship project. However, studies showed that CSEM sensitivity for Aurora, due to its depth, is likely too low. This led to further exploration of the possibility of using a well as an antenna to enhance electromagnetic signals, before the focus shifted to the Smeaheia model.

Northern Lights storage tanks. Photo by Svein Ove Søreide

The key activities in the project include:

Development of detailed Aurora models for CSEM sensitivity studies.
Improvements in software for 3D modeling and inversion of CSEM data.
Advanced model studies to investigate the use of wells as antennas for deeper storage sites.
Creation of a Smeaheia model and sensitivity studies for this area.

COSMOS combines the expertise of research institutions, industry partners, and technology providers, and the project is supported by an advisory scientific panel with national and international experts. The project’s goal is to reduce the uncertainty associated with monitoring CO₂ storage and thus contribute to safer and more cost-effective climate solutions.

5.3.2.17 ENSURE – Effective monitoring for long-term stability and transparent assessment of seismic hazard

The ENSURE project, led by NORSAR in collaboration with international partners, explores advanced methods for microseismic monitoring of CO₂ storage. The purpose of this ongoing project is to ensure long-term stability and prevent leaks through reliable monitoring of subsurface deformations. The project seeks to improve current methods for detecting, interpreting, and managing risks related to CO₂ storage, while strengthening public confidence in the technology.

Microseismic monitoring is the most effective method for detecting small, rapid deformations in reservoirs, which may indicate potential leakage or unwanted CO₂ spread. ENSURE develops high-performance and cost-effective monitoring systems, including through the use of new technology such as fiber optic sensors. The project compares data from various storage facilities in Canada, France, Norway, the UK, and the USA to establish tailored monitoring methods.

The main activities in the project include:

Development of advanced analysis tools for long-term monitoring of reservoir integrity.
Testing and optimization of traffic light systems, which provide clear guidelines for managing seismic activity. This includes measures such as reduced injection rate at the yellow level or temporary shutdown at the red level.
Analysis of public perception of CO₂ storage, through extensive surveys and economic experiments in Norway, Germany, the Netherlands, the UK, and Canada.

ENSURE also has a strong focus on communication. The project develops strategies to communicate complex technological concepts to different target groups. These strategies are based on empirical studies of how the public perceives the risks and benefits of carbon capture and storage (CCS). The results help to increase confidence in CCS technology.

5.3.2.18 Real-time monitoring for safe permanent CO₂ storage

Geomec Engineering AS carried out an innovative project to develop advanced tools that enabled real-time monitoring and optimization of CO₂ storage in the subsurface. The project addressed the need for cost-effective and safe storage of large quantities of captured CO₂.

Storing CO₂ in deep aquifers, abandoned oil and gas fields, or producing fields requires accurate monitoring of injection processes and storage conditions. If CO₂ leaks from the reservoir, the storage attempt will be unsuccessful, and costly measures will have to be implemented. Through the project, Geomec developed software that monitors the reservoir’s response during injection operations in real time, which contributes to safe and permanent storage conditions.

The solution supported various storage options, including deep aquifers, abandoned fields, and EOR, where injection of CO₂ increased oil recovery while CO₂ was stored permanently.

By understanding how geological formations react immediately during CO₂ injection, operators can tailor, monitor, and optimize the injection process. This increases the safety and capacity for permanent CO₂ storage in the reservoirs.

5.3.2.19 CO₂ DataShare: A collaborative platform for sharing CCS data

The CO₂ DataShare project, led by SINTEF, is focused on establishing a comprehensive platform for sharing crucial data related to CCS. This initiative has been supported in two phases by the CLIMIT program, highlighting its importance in advancing CCS technology.

CO₂ DataShare aims to share high-quality datasets from pilot, demonstration and industry-scale projects to enable research and development essential for building confidence in CO₂ storage as a greenhouse gas control strategy. Source: https://co2datashare.org/

Phase 1: Building the foundation (2017-)

The initial phase concentrated on creating the groundwork for a robust data-sharing platform. Key achievements included:

Developing a prototype platform to showcase the feasibility of sharing standardized datasets from diverse CCS projects.
Establishing data processing and quality assurance procedures to ensure consistency and reliability.
Fostering international collaboration through workshops and meetings, promoting knowledge exchange among researchers, industry, and authorities.
Identifying key research questions to guide data utilization and support targeted research and development.

“It is especially gratifying that Gassnova has contributed with own data from the work on the Smeaheia CO₂ storage prospect. We are very interested in the outcomes of this project, and it aligns perfectly with what Gassnova should bring to the table – sharing our knowledge.”

Kari-Lise Rørvik, director of Technology and Innovation at Gassnova

Phase 2: Expanding the vision (2024-2026)

With the foundation established, the second phase aims to expand the platform’s capabilities and impact. Key objectives include:

Broadening the scope to encompass data from the entire CCS chain, including capture and transport, in addition to storage.
Enhancing user experience by simplifying data sharing and incorporating tools for data inspection and visualization.
Creating a user forum to facilitate knowledge exchange and support benchmark studies and competitions using shared datasets.
Investigating synergies with other data-sharing initiatives like the European Open Science Cloud (EOSC) to increase visibility and interoperability.
Publishing new CCS datasets from Norwegian and international initiatives, accompanied by active dissemination through blogs, webinars, and social media.

Impact and significance

The CO₂ DataShare project is making substantial contributions to the CCS field. By fostering collaboration and knowledge exchange through data sharing, it accelerates innovation. It enables the assessment and replication of research and industry practices, validating findings and ensuring quality and reliability. The project also reduces costs and risks by sharing lessons learned, optimizing planning, and preventing costly errors. Furthermore, it builds competence by providing quality-assured data for educating future CCS experts. Finally, it strengthens international collaboration by creating a global network of CCS advocates to collectively advance CCS deployment.

5.3.3 Further work on monitoring and simulation

Improved monitoring technology: Continue the development of more accurate, sensitive, and cost-effective sensors and monitoring methods to detect potential leaks and monitor CO₂ migration in real time. This may include the use of fiber optic cables, distributed acoustic sensors, and advanced geophysical techniques.
More realistic simulation models: Develop more sophisticated models that take into account complex factors that affect CO₂ migration, including geochemical reactions, multiphase flow, geomechanical effects, and uncertainty in data.
Integration of data and models: Improve methods for integrating data from various sources, such as seismic surveys, well data, and geochemical analyses, to provide a more holistic picture of CO₂ storage and reduce uncertainty in simulations.
Machine learning and artificial intelligence: Explore the potential for using machine learning and artificial intelligence to analyze large datasets, improve the accuracy of simulations, and optimize monitoring strategies.

5.3.4 Conclusion

Monitoring and simulation are essential tools for ensuring safe and effective CO₂ storage. Through the CLIMIT program, important progress has been made in the development of monitoring technology and simulation models, but further work is needed to improve accuracy, reduce uncertainty, and optimize the CO₂ storage process. Continuous research and innovation in monitoring and simulation will be crucial to realizing the potential of CCS as an effective climate measure.

5.4 CLIMIT program category – CCS wells

For effective and safe CO₂ storage, it is critical to ensure the integrity and functionality of the wells used for CO₂ injection. The wells are the link between the surface and the storage reservoir, and any faults or leaks in the wells can compromise the entire storage process. CLIMIT supports research that addresses these challenges in the CCS wells program category.

5.4.1 Challenges

Well integrity: The wells must be designed and constructed to withstand the corrosive environment and high pressures associated with long-term CO₂ injection. Material degradation, corrosion, and fractures in the well construction can lead to leaks and reduce storage security.
Cement integrity: The cement used to seal the well and isolate the various formations must maintain its integrity over time. Cement degradation and cracks can lead to CO₂ leaks along the well.
Wellhead equipment: The wellhead equipment, which includes valves and control systems, must be reliable and functional to ensure safe and controlled injection of CO₂. Failures in the wellhead equipment can lead to uncontrolled releases or operational shutdowns.
Monitoring: Effective methods are needed to monitor the condition and integrity of the well, to identify potential problems early and take measures to prevent leaks.

5.4.2 The status on CCS well research

Several CLIMIT-funded projects have worked to improve understanding of well challenges in CO₂ storage and developed solutions to address the challenges:

5.4.2.1 Polymer resins for repairing leaks in CO₂ wells

Between 2016 and 2020, WellCemm AS led a project that focused on the development and testing of polymer resins to seal leaks in CO₂ storage wells. The aim was to find alternatives to traditional cementing, which has limitations in repairing cracks and leakage pathways in wells. ThermaSet® and EnvoSet®, temperature-activated polymer resins, were developed and tested as environmentally friendly and robust solutions to stop leaks.

Research and results

The project showed that both ThermaSet® and EnvoSet® could be effectively sealed into cracks of various sizes (from 72 µm to 500 µm) and provide a lasting seal. Tests under realistic conditions with supercritical CO₂ and CO₂-saturated water over 93 days confirmed that the resins retained their sealing properties and showed no measurable leaks.

Long-term experiments under simulated downhole conditions (100°C and 500 bar) were also performed to evaluate mechanical properties after exposure to CO₂-saltwater and pure saltwater. Although reductions in strength were observed after 1–6 months of exposure, the results showed that the resins stabilized and retained high strength over time.

Innovations and implications

Environmentally friendly development: EnvoSet®, an environmentally friendly resin, was commercialized as a sustainable solution for CO₂ wells.
New test method: The CAPT (Consistency under Applied Pressure Test) method was introduced to predict the curing process under downhole conditions, which improves the application of the resins in wells.
Increased well integrity: By using the resins, leaks from wells can be limited. This reduces environmental impact and increases the safety of CO₂ storage.

5.4.2.2 REcycled well PLUGging material to improve the outcome of CO₂ storage in geological reservoirs (RePlug)

In 2017, ReStone AS led a project to develop and test RePlug®, an innovative cement additive for use in Plugging and Abandonment (P&A) of CO₂ storage wells. The project focused on improving cement plugs by increasing their lifespan and resistance to CO₂, which is crucial for safe and long-term CO₂ storage in geological formations.

CT scans of small cores (2,5*4 cm) of RePlug blends before (a) and after (b) 4 weeks of ageing in seawater and supercritical CO2 at elevated pressures and temperatures. Red dots are pore spaces in the blend, and the (b) scan shows how the outer mantle of the core is sealed off, protecting the inner cement, and new minerals are formed on the surface of the core, sealing off potential micro annuli. Illustration: ReStone

Research and results

RePlug® was developed as a forward-looking, environmentally friendly additive based on Portland G-systems cement. It was tested and validated by SINTEF Petroleum AS under relevant pressure and temperature conditions. The results showed that RePlug® has unique properties such as:

Self-healing and CO₂ resistance: When the cement is exposed to CO₂, the porosity is reduced by up to 90%, which improves the seal and prevents leakage.
Ductile properties: RePlug® deforms upon crushing instead of failing brittlely, which increases robustness.
Reduced CO₂ footprint: Production has a lower carbon footprint than ordinary Portland G cement.
Slight expansion during curing: This prevents shrinkage and ensures stronger bonding to steel and formations.

These properties make RePlug® particularly suitable for wells that cross potential CO₂ storage formations, and improve the possibility of success in carbon storage projects.

Implications

RePlug® represents a breakthrough in technology for P&A and CO₂ storage. The product can accelerate the implementation of CCS projects by reducing the risk of leakage while improving the sustainability of cementing processes. The project has also contributed to increased expertise in geochemistry, petrology, and well plugging.

5.4.2.3 Ultrasound to verify that the cementing of the annulus is impermeable

The project, led by Equanostic AS, developed a software solution called VRI to improve the verification of cementing in wells used for CO₂ storage. Safe storage of CO₂ requires that the cementing around the well’s steel pipe forms an impermeable barrier to prevent leaks. Traditional methods for verifying this using ultrasound are complex and can be inaccurate.

The VRI solution analyzes ultrasound data using advanced algorithms and machine learning. This provides a more accurate assessment of the cement’s integrity. The system can identify whether there is solid material or liquid behind the steel pipe and estimate potential leakage pathways. This gives operators better tools to assess the condition of the well and take necessary measures.

The project tested VRI on over 20 wells in the North Sea and the Barents Sea, with positive results. The improved verification of the cementing contributes to increased safety in CO₂ storage and reduces the risk of environmental damage and financial losses. The solution has received great interest from the industry and can accelerate the safe implementation of CO₂ storage as an effective climate solution.

5.4.2.4 Studies of interfaces between fluids during cementing of CCS wells

The project (2017–2020), led by SINTEF, focused on improving the cementing process for CO₂ storage wells by developing methods to track interfaces between fluids during cementing. Good cementing is crucial for well integrity, as cement acts as a barrier against leakage of stored CO₂. This is particularly important in CCS wells, where high injection pressures and the reactive nature of CO₂ place stringent demands on the materials.

Staff and work at Equanostic in Oslo. Photo: Peter Holgersson AB

The project identified a significant knowledge gap: while research has previously focused on the material properties of cement, there has been little attention to how cement is actually placed in the well. Defects that can occur during cementing, such as incompletely filled cement or channels, can pose a leakage risk over time.

Research and results

Through experimental trials and numerical modeling, the project developed new methods for tracking fluid interfaces using small particles (“tags”). These particles can be used to visualize the 3D geometry of the cement front and identify defects such as pockets and channels in the cement.

The results include:

Development of a new conceptual approach for tracking fluid interfaces in wells.
Design and use of custom-designed experimental setups, including a Hele-Shaw cell, to study fluid flow and particle dynamics.
Numerical simulations that validate the effectiveness of particle tracking under relevant well conditions.
Publication of 11 peer-reviewed articles and presentations at 16 conferences, with significant attention from both academia and industry.

Significance and implications

The project has the potential to improve the cementing process in CCS wells by reducing uncertainty and the risk of leakage. The technology can also contribute to better monitoring of well barriers.

5.4.2.5 Cost-effective and robust CO₂ injection wells (IntoWell)

The IntoWell project (2021–2024), led by Equinor in collaboration with SINTEF, is working to develop innovative solutions for future CO₂ storage wells. The goal is to ensure robust and cost-effective design that supports large-scale implementation of CCS, including the Longship project.

The project focuses on improving well integrity through material optimization, multi-physics simulations, and risk management. Geological storage of CO₂ requires injection wells that can withstand extreme pressure and temperature conditions without compromising safety or functionality. IntoWell combines laboratory data with numerical models to develop a toolbox that supports engineers in designing and evaluating wells more accurately.

Illustrasjon av IntoWell’s underliggende idé. Illustrasjon. — Illustration of IntoWell’s underlying idea. Illustration: IntoWell.

This toolbox contains:

Improved understanding of material properties: Insight into how well materials behave under extreme conditions, which provides a basis for better material selection.
Experimental database: Data from laboratory tests covering the mechanical properties of various materials, providing engineers with valuable references for design.
Multi-physics simulations: Tools that evaluate mechanical integrity and optimize injection strategies, which reduces risk and improves operational reliability.

Expected effects

Increased well integrity: Reduced risk of leakage and environmental damage.
Cost reductions: Lower construction and operating costs for injection wells.
Scientific progress: New knowledge about materials and simulation tools.

5.4.2.6 Well control for CO₂ wells

This ongoing project, led by eDrilling AS, focuses on developing software and services for the safe drilling of CO₂ wells in areas with existing CO₂ storage. The project addresses critical knowledge gaps related to well control when drilling into CO₂ storage reservoirs.

Full-scale CO₂ storage requires extensive analysis and understanding of the reservoir and formation to eliminate the risk of underground leaks. The project is developing qualified software that helps operators maintain and restore well control in CO₂ wells. The tool is used both for planning and risk assessment before drilling operations, as well as a system for anomaly detection during the drilling itself.

By addressing risks such as CO₂ kicks and uncontrolled blowouts, as well as cooling effects caused by the Joule-Thomson effect, the project helps to reduce the risk of accidents and environmental damage. The development of methodologies to assess the suitability of drilling fluids and simulate complex drilling conditions is central to this work.

The project’s results will support the scaling up of global ambitions for geological CO₂ storage by enabling safer drilling operations in CO₂ storage areas.

5.4.2.7 The eXRES project – Development of an external resistivity meter for “logging while coring”

The project is ongoing, led by CoreAll AS, and focuses on developing an external resistivity meter for real-time logging of formation resistivity during both drilling and core drilling, aimed at CCS. The project addresses the need for better documentation of the reservoir’s geological properties for safe CO₂ storage.

CoreAll has previously developed the “Intelligent Coring System” (ICS), which includes sensors for resistivity and gamma radiation, but the existing sensor only measures during core drilling. To optimize CoDril™ technology, which combines drilling and core drilling with the same tool and saves time and costs, the eXRES project is developing an external resistivity meter that enables continuous measurement during both operations.

The technology is expected to reduce operating time by 3–6 days per CCS exploration well. This will result in significant savings in fuel consumption and emissions of CO₂ and NO_x. In addition, it will improve the characterization of reservoirs, which is essential for safe and effective CO₂ storage.

5.4.3 CLIMIT-funded well integrity projects

Well integrity is a crucial factor for safe and effective storage of CO₂ in the subsurface. Wells act as bridges between the surface and the reservoirs where CO₂ is stored, and their integrity determines whether the stored gas remains securely trapped or whether it can leak back into the atmosphere. To meet the stringent requirements of carbon capture and storage, several projects have been initiated to improve well integrity through innovative methods and materials.

5.4.3.1 Improving CO₂ well integrity through studies of materials from Ketzin wells

This project was led by SINTEF and aimed to maximize the learning potential from Ketzin, Germany’s first pilot plant for CO₂ storage. By analyzing materials recovered from wells and comparing them with data from logging and monitoring tools, the researchers sought to understand when, where, why, and how materials fail in a CO₂ well environment. Through these studies, vulnerabilities in well materials were identified and strategies were developed to improve integrity during CO₂ storage. The project contributed to increased understanding of material properties and their behavior in contact with CO₂.

5.4.3.2 XMAS – Methods for continuous remote monitoring of the integrity of CO₂ wells

The XMAS project, led by Aker Solutions AS, focused on developing non-invasive methods for continuous monitoring of well integrity. A major challenge in CO₂ storage is the lack of cost-effective methods for assessing the integrity of plugged and abandoned wells, especially on the Norwegian continental shelf.

The project combined numerical studies, experiments, and engineering to investigate how various signals can be used to evaluate well integrity without having to enter the well. By studying the transmission of seismic and electromagnetic signals along the well’s construction materials, the team identified potential methods for remote sensing. XMAS thus helped to build significant expertise in non-invasive well monitoring and established new collaborations with industry partners and research groups globally.

5.4.4 Development and testing of new cement types for improved well integrity in CCS

The CEMENTEGRITY project, led by the Institute for Energy Technology (IFE), attempted to develop and test materials that provide better sealing of wells exposed to stored CO₂ in underground reservoirs. The goal was to create sealing materials that prevent leaks, are self-repairing if leaks occur, and have a smaller environmental footprint than current solutions.

Through experimental research on various sealing compounds and support from numerical modeling, the project identified critical properties that ensure the long-term integrity of well sealing materials. These findings can be used to develop new materials for CO₂ storage, thus ensuring the long-term integrity of the storage reservoirs.

5.4.5 Well barrier integrity test unit – BTU

This ongoing project, led by Vedeld AS, aims to develop a well barrier test unit (BTU) that enables testing and monitoring of subsea CO₂ injection wells in a safe and cost-effective manner. In today’s subsea wells, testing of the well barriers is performed by applying pressure to sections inside the well through a service line in a subsea umbilical. This is a significant cost driver. The BTU project seeks to eliminate the need for such a service line by integrating the test unit directly into the CO₂ injection well with an electrical vertical Christmas tree (eVXT). This innovative concept paves the way for complete removal of the umbilical, reduces costs and environmental impact, and improves well integrity during CO₂ storage.

5.4.6 Significance of well integrity projects for CO₂ storage

Well integrity projects play a crucial role in ensuring safe and effective storage of CO₂ in the subsurface. By addressing challenges related to material failure, development of new sealing materials, implementation of non-invasive monitoring methods, and innovative testing of well barriers, they help to strengthen confidence in CCS technologies.

5.4.7 Further work on CO₂ wells

Improved well integrity: Continue research on materials and design for wells that are more resistant to corrosion and degradation in CO₂ environments. This includes the development of new materials, such as special steel types and polymers, as well as improved methods for monitoring the condition of the well over time.
Optimization of cement technology: Further develop cement mixtures with improved properties for CO₂ wells, such as increased resistance to corrosion, cracking, and permeability. This also includes research on new methods for placing and monitoring cement in the well.
Advanced wellhead equipment: Develop more reliable and functional wellhead equipment, including sensors and monitoring systems to ensure safe and controlled injection of CO₂. This may include technology to control injection rates and pressures more precisely, as well as technology to monitor the condition of the well in real time.
Integrated well modeling: Develop integrated models that combine well integrity, cement analysis, and geomechanical modeling to provide a comprehensive risk assessment for CO₂ injection wells.

5.4.8 Conclusion

Well integrity is a critical factor for safe and effective CO₂ storage. Through the CLIMIT program, significant progress has been made in understanding and addressing challenges related to well construction, material selection, cement technology, and monitoring. Further work is needed to improve well integrity, optimize design and operation, and reduce the risk of leaks. Continuous research and innovation in well technology will be crucial to implementing CO₂ storage on a large scale and contributing to achieving climate goals.

Publication: CLIMIT`s Project Portfolio

5. Storage

5.1 The CLIMIT program – Geological CO2 storage

5.1.1 Reservoir and caprock

5.1.2 Monitoring and simulation

5.1.3 CCS wells

5.1.4 Technological development of geological storage

5.1.5 Regulations and framework for CO2 storage

5.1.6 CLIMIT’s perspective on the commercialization of CO2 storage

5.2 CLIMIT program category – Reservoir and caprock

5.2.1 Challenges

5.2.2 The status on reservoir and caprock research

5.2.2.1 A frozen frontier – Exploring CO2 storage in Longyearbyen

5.2.2.2 Optimized CO2 storage in sloping aquifers (Upslope)

5.2.2.3 The SWAP projects: Groundbreaking steps toward future CO2 storage

“The data suggest the seal is solid. The reservoir has thick, laterally extensive rock units, indicating that the area may potentially accommodate large volumes of CO2.”

“With future scaling of Northern Lights, the area we are exploring could likely serve as a storage location. This means we might utilize the infrastructure built in the initial project phases, resulting in significant cost savings.”

“CLIMIT’s financial contributions made SWAP and SWAP 2 possible. Without this support and the exploration drilling results, CO2 storage at Smeaheia would likely have been delayed by several years.”

5.2.2.4 Geological storage of CO2: Mathematical modeling and risk assessment (MatMoRA-II)

5.2.2.5 Safe long-term storage sealing of CO2 in hydrate

5.2.2.6 Protection of caprock integrity for large-scale CO2 storage (PROTECT)

5.2.2.7 CO2 storage in the North Sea: Quantification of uncertainties and error reduction (CONQUER)

5.2.2.8 CO2 seal bypass

5.2.2.9 Avoiding loss of CO2 injectivity

5.2.2.10 Stress path and hysteresis effects on integrity of CO2 storage site (SPHINCSS)

5.2.2.11 Understanding of CO2 dissolution in oil by convection-driven mixing and wettability alteration (UNCOVER)

5.2.2.12 Nanoparticles for stabilizing CO2 foam for combined storage and energy production from mature oil fields

5.2.2.13 Preventing loss of near-well permeability in CO2 injection wells

5.2.2.14 Quantification of fault-related leakage risk (FRISK)

5.2.2.15 Overburden analysis and seal integrity study for CO2 sequestration in the North Sea (OASIS)

5.2.2.16 Reusing depleted oil and gas fields for CO2 sequestration

5.2.2.17 THERMESI – Thermal Effects on Seal Integrity

5.2.2.18 Beyond the barrel – From oil recovery to climate recovery

5.2.3 Further work on CO2 reservoir and caprocks

5.2.4 Conclusion

5.3 CLIMIT program category – Monitoring and simulation

5.3.1 Challenges

5.3.2 The status on monitoring and simulation research

5.3.2.1 The Svelvik projects – Innovative monitoring for safe CO2 storage

5.3.2.2 The H-NET projects – Innovative seismic monitoring for safe CO2 storage

5.3.2.3 The ACT projects – Innovative monitoring for safe CO2 storage

5.3.2.4 Distributed Seismic Monitoring for Geological CO2 Storage (DemoDas)

5.3.2.5 The HPC Projects for gigatonne CO2 storage – Groundbreaking software for large-scale storage challenges

“The advantage of OPM Flow being developed in an open framework is that various actors can contribute to the further development and improvement of the software. CO2 storage is something we have to work on together, and the industry must be involved.”

“The results from this project will enable operators to assess CO2 storage more effectively and plan for large-scale field development on a gigatonne scale.”

5.3.2.5 Capacity of large-scale CO2 storage in North Sea sloping aquifers from numerical simulation

5.3.2.6 Simulation and optimization of large-scale CO2 injection at basin scale in the North Sea

5.3.2.7 Monitoring and control of pore pressure for safe and effective CO2 storage

5.3.2.8 CO2 permeability along fragmented shale interfaces

5.3.2.9 Environmental impacts of leakage from sub-seabed CO2 storage

5.3.2.10 Bayesian monitoring design (BayMoDe)

5.3.2.11 Induced-seismicity geomechanics for controlled CO2 storage in the North Sea (IGCCS)

5.3.2.12 Prediction of CO2 leakage from reservoirs during large-scale storage

5.3.2.13 Use of noble gas signatures in monitoring systems for offshore CO2 storage

5.3.2.14 Techniques for identifying safe CO2 storage

5.3.2.15 Accelerating CSEM technology for efficient and quantitative CO2 monitoring

5.3.2.16 CSEM for monitoring CO2 storage

5.3.2.17 ENSURE – Effective monitoring for long-term stability and transparent assessment of seismic hazard

5.3.2.18 Real-time monitoring for safe permanent CO2 storage

5.3.2.19 CO2 DataShare: A collaborative platform for sharing CCS data

“It is especially gratifying that Gassnova has contributed with own data from the work on the Smeaheia CO2 storage prospect. We are very interested in the outcomes of this project, and it aligns perfectly with what Gassnova should bring to the table – sharing our knowledge.”

5.3.3 Further work on monitoring and simulation

5.3.4 Conclusion

5.4 CLIMIT program category – CCS wells

5.4.1 Challenges

5.4.2 The status on CCS well research

5.4.2.1 Polymer resins for repairing leaks in CO2 wells

5.4.2.2 REcycled well PLUGging material to improve the outcome of CO2 storage in geological reservoirs (RePlug)

5.4.2.3 Ultrasound to verify that the cementing of the annulus is impermeable

5.4.2.4 Studies of interfaces between fluids during cementing of CCS wells

5.4.2.5 Cost-effective and robust CO2 injection wells (IntoWell)

5.4.2.6 Well control for CO2 wells

5.4.2.7 The eXRES project – Development of an external resistivity meter for “logging while coring”

5.4.3 CLIMIT-funded well integrity projects

5.4.3.1 Improving CO2 well integrity through studies of materials from Ketzin wells

5.4.3.2 XMAS – Methods for continuous remote monitoring of the integrity of CO2 wells

5.4.4 Development and testing of new cement types for improved well integrity in CCS

5.4.5 Well barrier integrity test unit – BTU

5.4.6 Significance of well integrity projects for CO2 storage

5.4.7 Further work on CO2 wells

5.1 The CLIMIT program – Geological CO₂ storage

5.1.5 Regulations and framework for CO₂ storage

5.1.6 CLIMIT’s perspective on the commercialization of CO₂ storage

5.2.2.1 A frozen frontier – Exploring CO₂ storage in Longyearbyen

5.2.2.2 Optimized CO₂ storage in sloping aquifers (Upslope)

5.2.2.3 The SWAP projects: Groundbreaking steps toward future CO₂ storage

“The data suggest the seal is solid. The reservoir has thick, laterally extensive rock units, indicating that the area may potentially accommodate large volumes of CO_₂.”

“CLIMIT’s financial contributions made SWAP and SWAP 2 possible. Without this support and the exploration drilling results, CO_₂ storage at Smeaheia would likely have been delayed by several years.”

5.2.2.4 Geological storage of CO₂: Mathematical modeling and risk assessment (MatMoRA-II)

5.2.2.5 Safe long-term storage sealing of CO₂ in hydrate

5.2.2.6 Protection of caprock integrity for large-scale CO₂storage (PROTECT)

5.2.2.7 CO₂ storage in the North Sea: Quantification of uncertainties and error reduction (CONQUER)

5.2.2.8 CO₂ seal bypass

5.2.2.9 Avoiding loss of CO₂ injectivity

5.2.2.10 Stress path and hysteresis effects on integrity of CO₂ storage site (SPHINCSS)

5.2.2.11 Understanding of CO₂ dissolution in oil by convection-driven mixing and wettability alteration (UNCOVER)

5.2.2.12 Nanoparticles for stabilizing CO₂ foam for combined storage and energy production from mature oil fields

5.2.2.13 Preventing loss of near-well permeability in CO₂ injection wells

5.2.2.15 Overburden analysis and seal integrity study for CO₂ sequestration in the North Sea (OASIS)

5.2.2.16 Reusing depleted oil and gas fields for CO₂ sequestration

5.2.3 Further work on CO₂ reservoir and caprocks

5.3.2.1 The Svelvik projects – Innovative monitoring for safe CO₂ storage

5.3.2.2 The H-NET projects – Innovative seismic monitoring for safe CO₂ storage

5.3.2.3 The ACT projects – Innovative monitoring for safe CO₂ storage

5.3.2.4 Distributed Seismic Monitoring for Geological CO₂ Storage (DemoDas)

5.3.2.5 The HPC Projects for gigatonne CO₂ storage – Groundbreaking software for large-scale storage challenges

“The advantage of OPM Flow being developed in an open framework is that various actors can contribute to the further development and improvement of the software. CO₂ storage is something we have to work on together, and the industry must be involved.”

“The results from this project will enable operators to assess CO₂ storage more effectively and plan for large-scale field development on a gigatonne scale.”

5.3.2.5 Capacity of large-scale CO₂ storage in North Sea sloping aquifers from numerical simulation

5.3.2.6 Simulation and optimization of large-scale CO₂ injection at basin scale in the North Sea

5.3.2.7 Monitoring and control of pore pressure for safe and effective CO₂ storage

5.3.2.8 CO₂ permeability along fragmented shale interfaces

5.3.2.9 Environmental impacts of leakage from sub-seabed CO₂ storage

5.3.2.11 Induced-seismicity geomechanics for controlled CO₂ storage in the North Sea (IGCCS)

5.3.2.12 Prediction of CO₂ leakage from reservoirs during large-scale storage

5.3.2.13 Use of noble gas signatures in monitoring systems for offshore CO₂ storage

5.3.2.14 Techniques for identifying safe CO₂ storage

5.3.2.15 Accelerating CSEM technology for efficient and quantitative CO₂ monitoring

5.3.2.16 CSEM for monitoring CO₂ storage

5.3.2.18 Real-time monitoring for safe permanent CO₂ storage

5.3.2.19 CO₂ DataShare: A collaborative platform for sharing CCS data

“It is especially gratifying that Gassnova has contributed with own data from the work on the Smeaheia CO₂ storage prospect. We are very interested in the outcomes of this project, and it aligns perfectly with what Gassnova should bring to the table – sharing our knowledge.”

5.4.2.1 Polymer resins for repairing leaks in CO₂ wells

5.4.2.2 REcycled well PLUGging material to improve the outcome of CO₂ storage in geological reservoirs (RePlug)

5.4.2.5 Cost-effective and robust CO₂ injection wells (IntoWell)

5.4.2.6 Well control for CO₂ wells

5.4.3.1 Improving CO₂ well integrity through studies of materials from Ketzin wells

5.4.3.2 XMAS – Methods for continuous remote monitoring of the integrity of CO₂ wells

5.4.6 Significance of well integrity projects for CO₂ storage

5.4.7 Further work on CO₂ wells