CO2 Geological Storage: Mineralization in mafic rocks

Project Information

GEOMIMIC

Grant agreement ID: 101106038

DOI

10.3030/101106038

EC signature date 24 April 2023

Start date 16 September 2023

End date 15 September 2026

Funded under

• Marie Skłodowska-Curie Actions (MSCA)

Total cost

No data

EU contribution

€ 236 499,60

Coordinated by

UNIVERSIDADE DA CORUNA
Spain

Periodic Reporting for period 1 - GEOMIMIC (CO2 Geological Storage: Mineralization in mafic rocks)

Reporting period: 2023-09-16 to 2025-03-15

Summary of the context and overall objectives of the project

The GEOMIMIC project addresses one of the most pressing global challenges: climate change. As Europe advances toward climate neutrality, the European Green Deal highlights the need for innovative and effective strategies to reduce carbon dioxide (CO2) emissions. Among these, carbon capture and storage (CCS) -including carbon mineralization- offers a promising solution for permanent and safe CO2 storage.

GEOMIMIC focuses on carbon mineralization in mafic rocks, a process in which CO2 is converted into stable carbonate minerals through chemical reactions with rock-forming minerals. By integrating field observations, laboratory experiments, and advanced simulations, the project aims to improve understanding of fluid flow and fracture-matrix interactions to enhance the efficiency of CO2 storage in fractured mafic formations. The project's main objectives are to:

• Analyze how fracture networks, fluid flow and geochemical reactions influence CO2 mineralization in mafic rocks;
• Develop laboratory and numerical tools to evaluate the coupled hydro-chemo-mechanical behavior of the system;
• Provide open-access data and results to support future CCS initiatives and promote knowledge transfer across Europe and beyond.

The expected impact is twofold: scientific and societal. Scientifically, GEOMIMIC will generate new knowledge on the behavior of fractured rocks and carbon mineralization processes, informing future research and innovation in geoscience and energy transition technologies. Societally, the project contributes to Europe's climate goals by supporting the development of reliable and sustainable CCS methods, potentially influencing new industrial practices and policy decisions across sectors.

Work performed from the beginning of the project to the end of the period covered by the report and main results achieved so far

During the course of the GEOMIMIC project, substantial progress was made toward advancing the understanding of carbon mineralization in fractured mafic rocks. The work followed a multidisciplinary approach, combining field studies, laboratory experiments and numerical simulations, structured around three core research objectives.

1) Fracture characterization: This objective was achieved through the development of a comprehensive fracture topology in mafic formations. By analyzing both existing literature and new field data, key relationships between fracture properties, mineralogy and CO2 storage potential were established. The resulting dataset, available on Zenodo, serves as a valuable open-access reference for researchers involved in site characterization and comparative studies of CO2 storage in mafic rocks.

2) Assessment of transport properties: Significant progress was made in understanding how CO2–water–rock interactions influence fluid flow and transport behavior. Notably, hydro-mechanical effects such as swelling were observed during fluid injection in mafic rocks, prompting further investigation into capillary-induced deformation and its implications for transmissivity and storage integrity. Laboratory experiments under controlled advection regimes elucidated dissolution kinetics and mineral reactivity, while complementary numerical simulations provided insights into fluid flow within hexagonal fracture networks.

3) Coupled processes: Initial experiments have begun to clarify the influence of chemo-mechanical processes on fracture propagation. Early findings indicate that water content plays a critical role in controlling reaction rates and mineral precipitation.

Progress beyond the state of the art and expected potential impact (including the socio-economic impact and the wider societal implications of the project so far)

The GEOMIMIC project has delivered new insights into CO2 storage in fractured mafic basalts:

• Fine-grained and fractured mafic basalts are strong candidates for CO2 storage. Their fracture networks are shaped by mineralogy, formation history and cooling rates. Block size (dc) and fracture aperture (b) follow log-normal distributions (σ/μ ≈ 0.4) with aperture proportional to block size (β = b/dc), typically ranging from ~0.007 to ~0.06 depending on mineralogy.
• Fracture aperture differences are amplified by dissolution, potentially leading to flow channeling. However, hexagonal fracture topologies tend to limit positive feedbacks and delay localization.
• Storage capacity in fractures and matrix—whether supercritical or dissolved—is independent of columnar geometry. Fractures dominate when matrix porosity n < 2β.
• Mineralization is favored due to its high capacity and long-term stability. However, it is a volume-positive reaction that may reduce fracture transmissivity.
• Mineralogy is a key control, governing both fracture formation and behavior during carbon mineralization, including swelling and transmissivity shut-off.
• Swelling effects observed during injection into initially dry rock highlight the role of hydromechanical processes in carbon mineralization. In particular, deformation-induced transmissivity loss is linked to suction cancellation upon wetting.
• Fluid flow rate directly influences residence time and the evolution of chemical reactions. pH emerges as a key regulator of primary mineral dissolution and the availability of cations necessary for secondary carbonate formation.

GEOMIMIC. Fracture topology and CO2 injection in hexagonal fracture networks