Geothermal exploration and reservoir modelling of the United Downs deep geothermal project, Cornwall (UK)

Two deep geothermal wells, one of which is the deepest onshore UK well, have been successfully drilled to intersect Porthtowan Fault zone in early Permian high heat flow Carnmenellis Granite, part major post-Variscan Cornubian batholith underlies SW England. The drilling target was prognosed at 4 5 km depth from existing surface data and limited geophysics. It a late Variscan complex strike-slip fault with an episodic reactivation history, possibly as Tertiary, associated fluid on geological timescale including present day springs mines. Logging initial hydraulic testing carried out help define reservoir volume, where temperatures are around 180 °C. Initial modelling based fracture induced micro-seismicity during injection afterwards indicates that open fractures aligned close maximum horizontal stress >4 critical extension or shear subset them hydraulically active. These results encouraging for this project, aims produce power heat, well other similar ventures region.