Why is this research needed?

The recent Mission Innovation Carbon Capture Innovation Challenge (MI CCIC) report outlines that advances in CO₂ monitoring are needed to enable storage performance verification at a higher level of certainty, both during and following injection operations. This monitoring must allow the fate of the injected CO₂ to be quantified and provide reassurance that CO₂ is not leaking from the storage site.

The ability to identify buoyant and potentially mobile structurally retained CO₂ and residual or solubility trapped CO₂ is essential to understand how to engineer a secure storage site. However, it is difficult to measure and often poses the single greatest uncertainty in a CCUS project. To date, few studies have attempted to provide a full assessment of residually and solubility stored CO₂ from within the storage site at reservoir scale. Furthermore, leakage of CO₂ from a breached storage site may intercept shallow aquifers, surface body waters, and escape to the atmosphere, which can be hazardous to both ecosystems and human health.

The current means to distinguish man-made CO₂ from that naturally present in the subsurface is to add geochemical tracers to the injected CO₂ and monitor for them. Whilst artificial chemical tracers have proved to be successful at tracking CO₂ injection at the pilot scale, these tracer compounds are expensive and their co-injection will be cost prohibitive at
commercial scale storage sites, where millions of tonnes of CO₂ will be injected over decades.

What is this research investigating?

The work proposed here will determine the fate of CO₂ injected into the FRS site by quantifying both the level of CO₂ residually and solubility trapped within the reservoir formation. This will be achieved geochemically, using a combination of stable oxygen isotopes to resolve CO₂ pore space saturation (amount of CO₂ dissolved and residually trapped) within the injection formation and inherent noble gas and stable carbon isotopes to quantify the amount of CO₂ dissolved.

The second part of the work will establish the effectiveness of inherent tracers in identifying CO₂ migration from a CO₂ storage site. This will resolve any changes in the stable carbon, Kr and Xe and radiocarbon fingerprints from baseline levels in the overburden above the FRS injection horizon. This programme will directly address the need for advances in monitoring to enable CO₂ storage performance verification at a higher level of certainty, both during and following injection operations, by verifying inherent tracing tools as tracers of both the fate of injected CO₂ and CO₂ migration.

We will work with one of the world’s leading research organisations focused on CCS, the Containment and Monitoring Institute of Carbon Management Canada. They operate a dedicated research facility focused on CO₂ storage, their Field Research Station (FRS) located near the town of Brooks in Alberta. This site has secured $9M of Federal and Provincial
Government funding to date and provides a unique opportunity to develop, refine and calibrate monitoring systems and technologies. This provides an important asset for UK CO₂ storage research as the nation currently lacks such an extensive CO₂ injection research site. The project also has the support of Natural Resources Canada, who are undertaking bi-monthly sampling of the shallow groundwaters above the FRS, and the proposed programme of work will compliment this ongoing monitoring operation.

The proposed work will directly address two of the Mission Innovation report storage Priority Research Directions (PRDs), namely PRD4 ‘developing smart convergence monitoring to demonstrate containment and enable storage site’ and PRD 5 ‘realizing smart monitoring to assess anomalies and provide assurance’. The MI CCIC report specifically cites that ‘methods that use tracers in new and innovative ways are of interest.’