Project title: CO2 Hydrate Sealing potential for Carbon Capture and Storage
Researcher: Dr Srikumar Roy
Research hypothesis: CO2 hydrate formation in shallow marine sediments is analogous to the vast abundance of methane hydrates forming from seeping light hydrocarbons in European waters. Whilst recent work suggests that methane hydrates in nature may be susceptible to global warming (Ruppel and Kessler, 2017), CO2 hydrates, due to their preferential thermodynamic stability, have a low susceptibility to a warming climate. The additional sealing mechanism provided by CO2 as a solid hydrate could therefore provide significant potential for offshore Europe, where the predicted thickness of the CO2 hydrate stability zone (HSZ) may be as thick as the upper 450m of sediments. The above discussion suggests, therefore, that hydrate-based sealing may play a significant role in de-risking prospective CO2 storage sites across Europe and globally, especially where the reservoir and caprock are situated below thick sedimentary sequences within the CO2 gas hydrate stability zone. This CO2-hydrate secondary self-sealing mechanism is not, however, well-investigated and is the subject of this proposed project. The main hypothesis of the proposal is that leaking CO2 may self-seal overlying sedimentary cover sequences and thereby provide a secondary hydrate seal to deeper CO2 stores within either depleted reservoirs or saline aquifers. To test this hypothesis, a series of laboratory and numerical experiments will be conducted covering a broad range of scales.
The proposed project is a continuation iCRAG research on the exploration and associated hazards of natural gas hydrates and is in alignment with iCRAG2’s proposed research on Carbon Capture and Storage (CCS) in the context of Targeted Project 2.1: Energy Transitions — Offshore Basins (WP2 and WP4) and Targeted Project 2.2: Energy Transitions - Reservoirs and Storage (WP2). Over the last four years, in the context of a TP 4.4 – HC4.4PD2 iCRAG research and a later Irish Research Council Post-Doctoral Fellowship, Dr. Roy has focused on the exploration of methane hydrate provinces within the North-East Atlantic Margin (Minshull et al., 2020), including methane gas hydrate stability zone mapping and identification of potential methane hydrate provinces offshore Ireland (Roy and Max, 2018). During this period, he also established research collaborations with Germany and Norway, where he conducted experiments to support the formation of hydrates offshore Ireland (Roy et al., 2019). CO2 hydrate is thermodynamically more stable than methane hydrates, under similar physical settings, and can form an effective seal for CO2 leakage from underlying storage sites, a model supported by initial experiments on the seal integrity of CO2 hydrates over long timescales, in the context of a collaborative Carbon Capture and Storage (CCS) pilot project in Norway. Dr. Roy will utilize the know-how, collaborations and infrastructure arising from the above research to carry out the objectives of the proposed project.