Chemical monitoring during reinjection in the Laugaland geothermal system, N-Iceland

During a long term reinjection experiment which is now underway to extract thermal energy from 90-100 degrees C hot rock in the Laugaland geothermal system, North-Iceland, extensive chemical monitoring has taken place. Since the startup of reinjection in September 1997 until late February 1999, 590,000 m(3) or 12.5 l/s on average, of 6-21 degrees C warm return water from the district heating system of Akureyri has been pumped down into the geothermal system. No chemical changes have been observed in the geothermal water pumped from the production wells in the area during this 17 months period of reinjection. This indicates that the reinjection of this water does not induce significant cooling and subsequent precipitation of secondary minerals in the geothermal system.