Geological characterisation of deep saline aquifers for CO2 storage on the UK Continental Shelf using borehole and 3D seismic data

Global climate change is the major environmental challenge today. In order to prevent a significant rise in average temperatures, the International Energy Agency calculates that global emissions of greenhouse gasses – primarily carbon dioxide (CO2) – will need to be reduced by more than 50% by mid-century. Alternative energy sources will play an important role, but the reliance on fossil fuels is set to continue. Carbon Capture and Storage (CCS) is the most promising technology for mitigating the impact of fossil fuels. In CCS, CO2 is captured at power stations and transported to suitable underground storage sites where the CO2 is trapped away from the atmosphere on a timescale long enough for the atmosphere-ocean system to restore to natural levels of CO2 concentrations. The UK is well-placed to benefit economically and environmentally from CCS due to the proximity of power stations to potential offshore storage sites within depleted oil and gas fields and deep saline aquifers on the UK Continental Shelf (UKCS). The latter offer nearly twice the storage capacity of depleted hydrocarbon fields, yet the geological characteristics of deep saline aquifers – in particular the trap geometries, reservoir quality, compartmentalisation and sealing capacities – are poorly known. This project aims to use borehole data and seismic reflection surveys to provide improved geological characterisations of 3 deep saline aquifers systems, located in the Inner Moray Firth, Southern North Sea and East Irish Sea basins. These basins are all located close to sites of CO2 production, namely the major fossil fuel-burning power stations in eastern Scotland, eastern England and north Wales / northwest England. Specific objectives are for the student to: (1) identify locations and extents of potential structural traps within these aquifers; (2) use well-calibrated 2D and 3D seismic data to identify and map structural and stratigraphic heterogeneities within the aquifers (e.g. fault-bounded pressure compartments, distributions of high porosity facies etc); (3) estimate the likely sealing capacity of fault-bounded aquifer compartments with respect to CO2; and (4) risk the likelihood of leakage through reactivated faults during CO2 injection. The results of the project will be an important step towards realising the UK’s CCS potential. The project will be underpinned by a new partnership between Durham University Centre for Research into Earth Energy Systems (CeREES), IHS and Badley Geosciences. The CASE partners have identified long-term commercial and scientific benefits of participating in CCS programmes and intend to use the project to build technical expertise in this emerging field. CeREES will provide the student with training in seismic interpretation, structural geology, seismic sequence stratigraphy and seismic facies analysis. IHS is the leading source of borehole data for the UKCS and will provide the student with access to selected well and 2D and 3D seismic datasets. IHS will provide training in petrophysical analysis and definition of well-to-seismic ties, which are essential to characterising the aquifer prospects in each study area. Badleys are the UK’s leading suppliers of expertise and software in structural geology, with emphasis on quantifying fault seal and risking the likelihood of fault reactivation (hence leakage). Badleys will provide specialist training and software, which will enable the student to assess the sealing capacities of the aquifer prospects. DONG E&P, although not a CASE partner, is co-sponsoring the UK’s first Chair in CCS and Energy at Durham University and is providing access to 3D seismic datasets from key areas of the East Irish Sea basin. The student will gain the necessary technical skills, industry experience and contacts to pursue a career in CCS and/or the hydrocarbon sector. The training provided by this project will also meet a previously identified UK-wide shortage of scientists with expertise in CCS.