Unlocking the Secrets of CO2 Mineralisation: Clumped Isotopic Insights into CO2 mineralisation temperature in Carbfix 1 and Experimental Evidence of Reaction-Induced Fracturing in Basalt
Recent studies have investigated the potential of in-situ CO2 mineralisation within basalt formations as a sustainable method for securely storing anthropogenic CO2, evidenced by field demonstrations in Icelandic basalts and controlled laboratory experiments. The first Carbfix field test in Iceland demonstrated rapid CO2 mineralisation through the discovery of calcite precipitated on a well pump. Using clumped isotope analysis, we have determined the temperature conditions and fluid circulation during the mineralisation process. Our clumped isotopic analysis indicates that mineralisation temperatures were 10–16 °C higher than pre-injection levels, likely due to the upwelling of warmer waters through a fracture zone, as a result of water production through the monitoring well.
Complementing these field observations, laboratory experiments using x-ray microtomography on picrite cores replicated CO2 mineralisation under controlled conditions, simulating a geological reservoir environment at 170°C and 1.65 MPa. This induced mineralisation illustrated not only high volumes of CO2 conversion into primarily magnesite, along with dolomite and other carbonates, but also an increase in rock porosity and new fracture networks enhancing rock permeability.
These studies collectively enhance our understanding of the physical and chemical dynamics of CO2 mineralisation, providing a critical basis for modelling and forecasting the efficiency and reliability of geological CO2 storage strategies.
Short bio: Stuart Gilfillan is a Professor of Geochemistry in the School of GeoSciences, at University of Edinburgh. He was educated in Earth Science at the University of Glasgow (BSc) and Geology at the University of Manchester (PhD), and has over 19 years of post-PhD experience of innovative geochemical research in identifying CO2 origins and monitoring the geological storage of CO2. This research has developed a means of fingerprinting CO2 in order to track its movement and means of storage in subsurface reservoirs, as part of efforts to develop carbon capture and storage technologies. More recently, he has applied his expertise to the emerging GeoEnergy sector through novel monitoring of unconventional gas extraction, CO2 contamination in, and connectivity of, hydrocarbon fields and in-situ mineral storage of CO2. He has a keen interest in all areas of utilising the subsurface for energy production or storage and is currently the Programme Director for the GeoEnergy MSc course at Edinburgh, which he co-developed.
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