| Title | Unlocking the geothermal energy potential of old sedimentary systems: Linking reservoir quality, geomechanics and flow. |
|---|---|
| Authors | Skye Tisdell |
| Year | 2026 |
| Conference | World Geothermal Congress |
| Keywords | Hot Sedimentary Aquifer, Reservoir quality, Old Red Sandstone, United Kingdom |
| Abstract | The Central Belt of Scotland, home to major cities like Edinburgh and Glasgow, is a key region for addressing Scotland’s energy transition. Heat accounts for about 50% of the nation’s energy use and is largely fossil-fuel based, making heat decarbonisation essential to meet emissions targets and net-zero goals. The Central Belt is underlain by Devonian-Carboniferous formations of the Midland Valley of Scotland (MVS), featuring sedimentary sequences up to 5-6 km thick, mainly of fluvial/fluvio-deltaic origin. Some formations are being considered for low-enthalpy geothermal energy projects. Among the most promising targets is the Upper Devonian Kinnesswood Formation. However, poor reservoir quality—particularly reduced porosity and permeability from mechanical or diagenetic processes—poses a key challenge. We are investigating this by analysing samples from across the Central Belt using optical microscopy and laboratory measurements of porosity and permeability. Initial results show permeability values in the Kinnesswood Formation are relatively low (0.08 – 2.67 x 10⁻¹⁵ m²), while porosity ranges from 4% to 19%. These findings align broadly with limited published data, though other studies report a wider range of permeability (0.006 – 41 x 10⁻¹⁵ m²). Observations indicate pores are largely disconnected, mainly due to compaction or secondary calcite cement and clay minerals filling the pores and pore throats. Our ongoing work aims to expand this analysis to better understand heterogeneity within the MVS and how reservoir properties change with depth. Ultimately, our goal is to assess whether the MVS can provide viable geothermal resources to help decarbonise heat in Scotland’s Central Belt. |