Eden Geothermal restarts geothermal well testing, Cornwall, UK

Informing the public through its blog, Eden Geothermal explains that the microseismicity experienced is linked to well testing during the early stages of any deep geothermal development. This is because even low injection volumes and flow rates cause tiny movements along the natural fractures in the rock very deep underground. Normally, the events generated are far too small to be felt, or heard, at the surface. But occasionally an event is felt or heard. This doesn’t mean that felt events like the one last week are dangerous. Relatively small seismic events can be felt or heard, but they would need to be much bigger to cause cosmetic damage to buildings, or to be dangerous.

The compay started injection testing in late January, and over the past few weeks has taken a cautious approach, with gradual step increases in flow rates and volumes. In this period, the microseismic monitoring system has recorded over 300 microseismic events, nearly all of which have been far too small to be felt or heard – but which help to build a picture of where water is flowing in relation to the well. Following the felt event last Wednesday, no further injections were conducted to give time to review plans.

Now pumping is restarting at lower flow rates and volumes in order to complete this part of the company’s programme, which should be finished by the end of this month. Further phases of logging and testing are due to be carried out during April and May, and more information before each phase.

Source: Eden Geothermal