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Deepest hole drilled by GSI

Deepest hole drilled by GSI


Between July 2020 and January 2021 we have completed our deepest borehole to date. The hole was drilled to a depth of 1103m, near Attymany with the kind permission of the local landowner.

The hole was drilled with two purposes; to improve our understanding of the geology in the area, and to test the temperature of the groundwater at depth.

The hole was drilled close to a geological transition between ancient underwater environments, the shelf environment (known here as the Galway/Roscommon shelf) and the basin environment (here part of the Dublin basin). The hole was drilled through limestones, mudstones and small amounts of sandstone.

The GSI field team measured the temperature along the length of the hole using our fibre optic temperature sensing equipment. This allows us to see how the temperature changes with depth, which is important for understanding our geothermal energy resources. The temperature at the bottom of the hole is 32 degrees Celsius.