UKCCSRC Knowledge Exchange Conference 2025 – Parallel 1b: CO2 Storage (ECR Meeting Fund)

Oludare Amos Solademi (Robert Gordon University) and Abdulsalam Abdulkarim (Robert Gordon University) share their takeaways from “Parallel 1b: CO₂ Storage” at the UKCCSRC Knowledge Exchange Conference 2025.

This year’s UKCCSRC Conference, held at the University of Sheffield, brought together leading researchers, industry experts, and policymakers to discuss pathways for transforming our carbon future and to celebrate the UKCCSRC’s 20th anniversary. Highlighting innovative projects such as the Geomechanical Assessment of Caprock Integrity During CO₂ Injection into Depleted Hydrocarbon Reservoirs, the conference emphasised the dual challenges of caprock integrity and storage security as critical steps toward achieving a net-zero.

Abdusalam Abdulkarim’s insights on CO₂ sequestration underline a critical aspect of carbon management, focused on the importance of caprock integrity when storing CO₂ in depleted oil and gas reservoirs. The caprock, which is a geological layer that seals the reservoir, must maintain its ability to contain CO₂ to ensure safety and environmental protection. The risk of leakage, as Abdusallam pointed out, can stem from a variety of mechanisms. Hydraulic fracturing, for instance, occurs when the pressure from injected CO₂ surpasses the rock’s ability to withstand it, leading to cracks that can form pathways for gas to escape. Stress-induced shear failures can occur due to changes in pressure and temperature conditions, while chemical interactions between CO₂ and the caprock can compromise its integrity.

To mitigate these risks, the speaker emphasised the necessity of managing the injection process carefully. This involves maintaining the injection pressure below the caprock’s fracture threshold, thereby minimising the likelihood of unintentional fractures. Moreover, geochemical monitoring is essential. By tracking chemical changes in the reservoir, operators can pre-empt potentially damaging interactions with the rock matrix. The use of advanced materials or sealants is also crucial; these can fortify existing fractures and bolster the overall sealing properties of the caprock, making it more resilient against potential breaches. In addition to these preventive measures, real-time monitoring plays a vital role in ensuring the integrity of CO₂ storage sites. Techniques like microseismic or passive seismic monitoring can reveal early signs of changes in subsurface conditions, providing crucial data to pre-emptively address issues before they escalate into significant problems. Temperature and pressure sensors deployed within the reservoir offer operators the ability to respond swiftly to any deviations, thereby safeguarding the long-term sequestration efforts.

Stephen Vincent’s presentation outlined a three-year study of the Bunter Sandstone Storage Complex (BSSC) in the southern North Sea, focusing on its geological potential for carbon storage. The presentation was divided into three main components.

Chronostratigraphy and Correlation: The analysis of SM14 onshore reference well to establish a detailed Triassic section, creating a new palynological framework with ten zonations applicable offshore. He identified Milankovitch cycles that provided high-resolution age control, aiding in predicting mudstone barriers within the reservoir.

Reservoir Characterisation: Over 1,000 meters of core were examined through various analyses, revealing a complex depositional history and significant variations in porosity and permeability. The presentation clarified the sediment sources’ impact on reservoir properties.

Seal Potential Investigation: Detailed analyses of the Haisborough Group indicated strong heterogeneity in seals, particularly regarding halite content, while confirming the group’s viability as a sealing unit. The presentation emphasises the significance of the SM14 well for age control and seal characterisation, highlighting the Bunter Sandstone’s variability in reservoir quality and its arkosic composition. Recognition of Milankovitch-driven facies cycles aids in predicting mudstone barriers, while the heterolithic characteristics suggest that some intervals may act as flow baffles, potentially enhancing CO₂ trapping efficiency.

The presentation by Parvin Ahmadi focuses on the role of hysteresis in long-term underground CO₂ storage. Hysteresis refers to the path-dependent behaviour of fluid flow in porous media, where changes in saturation during drainage and imbibition affect capillary pressure and relative permeability. This phenomenon influences fluid distribution, trapping efficiency, plume migration, and ultimately the reliability of reservoir simulations. Using a conceptual 2D shoebox model and the Eclipse 100 simulator, the presentation explored hysteresis effects under controlled conditions with supercritical CO₂ injection followed by water injection.

Different reservoir permeabilities, injection rates, and hysteresis implementations were tested to assess their impact on CO₂ plume dynamics. Results reveal that neglecting hysteresis leads to overestimation of mobile CO₂ and underestimation of trapping capacity; while including it improves predictions of long-term containment. It also suggests that water or carbonated water injection can be strategically designed to further exploit these effects. The final message emphasises the need to use hysteresis-aware simulations for site selection, risk assessment, and storage design, cautioning against oversimplified models that could misrepresent long-term storage safety.

These presentations underscore a comprehensive strategy toward carbon management and sustainable energy production. They highlight the interplay between scientific innovation, technological applications, and environmental stewardship, paving the way for advancements that could drastically change how we approach energy consumption and CO₂ emissions. As the world continues to grapple with the effects of climate change, these discussions contribute to the development of actionable solutions that embrace both economic viability and ecological responsibility.