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Geothermal Drilling

Geothermal drilling is the process of creating a tubular void in the ground into which a geothermal probe is placed in order to extract low level energy. Complete thermal transfer along the length of the bore is important to its performance and this is where GeoDrill excels. Read on to find out how a geothermal system should be completed and why not all boreholes are equal

Step 1

Drilling a borehole for a geothermal system involves creating a circular void in the ground for anything up to 200m deep per bore depending on the heating demand. This involves drilling through the overburden (unconsolidated ground consisting of clays/gravels/sands etc.) until solid rock is reached. In order to keep this ground open a casing (steel tube) must be applied alongside the drill string.

Step 2

Once rock is reached casing of the hole is discontinued as the rock is naturally stable and the inner drill string continues drilling into the rock until the required borehole depth is reached.

Step 3

The inner drill string is then removed.

Step 4

At this point the geothermal loop is inserted along with a tremie pipe in order to fill the bore with grout.

Step 5

Grouting consists of pumping a thermally efficient bentonite clay and thermal sand mix under high pressure into the ground and filling from the bottom up. This eliminates any gaps or air pockets and ensures the probes have good thermal conductivity over the entire length of the bore.

Step 6

After grouting is complete, the casing is then retrieved. This is a very important step in drilling as it ensures full conductivity along the entire length of the bore and avoids drilling needless extra depth to compensate.

Geodrill, Weirs, Tuam, Co Galway Tel: 093 28166 / Fax: 093 28124