Scientists at Heriot-Watt University have been awarded €1 million to address risks related to geologic leakage from a subset of carbon capture and storage sites. 

Carbon Capture and Storage (CCS) involves using established technologies to capture carbon dioxide produced or released at source sites such as power stations or other industrial sites, transport it and then store it safely deep underground, as an alternative to emitting it into the atmosphere. 

The research will improve understanding of potential geologic leakage where there are (or may be) fractures in the caprock that keeps the CO2 in place underground. CO2 is physically trapped underneath tight sealing formations at elevated pressures.  

It may then chemically react with the formation it is stored in, thereby precipitating carbonate, or dissolve in the formation waters: these variables may increase or decrease flow across fractures which can make predicting, quantifying and monitoring potential leakages challenging. 

Dr Andreas Busch, associate professor of geoenergy in Heriot-Watt’s Institute for Petroleum Engineering, and his team are working with Shell Global Solutions; Risktec Solutions, a risk management company in the UK and the Netherlands and RWTH Aachen University in Germany on the DETECT project. DETECT will develop tools to allow CCS operators and other stakeholders to determine the risk of CO2 leakage at any CCS site.  

Dr Busch said: “A proposed CO2 reservoir usually has a solid cap rock, the rock layer on top of the reservoir that keeps the CO2 safely underground.  

The DETECT project will deliver guidelines for a complete lifecycle risk assessment methodology for potential CO2 leakage where there may be faults in the caprock.

Dr Andreas Busch

“At the Lyell Centre, we will design and carry out novel laboratory experiments that examine the fundamental aspects of leakage. The teams at the Institute of Petroleum Engineering and Shell will develop models that allow us to understand the physical and chemical mechanisms and study their implications for large-scale CO2 storage. 

“We will be examining how fluids migrate along faults and fractures of caprocks and seals, including the impact of reservoir stress changes, chemical reactions and swelling clays on fracture flow properties to deliver a well-informed risk assessment. The findings will be of great relevance to other related fields such as geothermal energy. 

“We want to fully understand realistic leakage rates and their implications, then develop monitoring plans and risk assessment schemes that operators could use in a variety of scenarios.”

Professor John Underhill, chief scientist of Heriot-Watt University and director of the Shell Centre for Exploration Geoscience, said: "The research to be undertaken by Dr Busch and the team will provide a critical test and validation of the seals for carbon storage sites. The results will help evaluate the risk or any threat of carbon dioxide leakage into the overburden, something that is crucial to know before any gas injection takes place."

Carbon capture and storage has been limited by its high commercial costs. However, the UK government recently committed to investing £100 million in CCUS and industrial innovation to drive down costs in its clean growth strategy. 

The DETECT project is part of the European Accelerating CCS Technologies initiative, which is funded by the European Commission and other European partners, including the Department for Business, Energy and Industrial Strategy in the UK.