Exploration of the Reykianes thermal brine area

The Reykjanes thermal brine area is located in the extreme southwest of Iceland on the subaerial continuation of the Reykjanes Ridge. This area is unique among thermal areas for its fluid composition. In the reservoir, where temperatures are between 250 and 290 °C the brine has the same salinity as sea water. However, the concentrations of some ions are different and can be explained by relatively simple interaction of sea water with the rock. The content of trace metals is low. In the upflow zone hot brine has been exchanged many times during the lifetime of the hydrothermal system. Surface activity covers an area of 1 km² and resistivity survey indicates that the system is of similar area above 900 m within the hyaloclastite formation surrounded by cold ground water of sea water composition. By contrast the system is more extensive in the underlying basalt formation consisting of lava flows and thick interbeds of hyaloclastites and sediments. At 2600 m depth P-velocity increases from 4.2 to 6.5 km/sec. At this depth the basalt formation is succeded by denser formation considered to be similar to the ≪ oceanic layer ≫. Due to its temperature and composition feasibility studies indicate that the brine could be exploited economically for the production of NaCl, KCl, CaCl₂ and possibly other components. Aquifers are abundant in the basalt formation. It is therefore recommended that production wells penetrate to depths of about 2600 m to withdraw brine within this permeable formation so as to ensure highest mass flow and minimize risk of cold sea water intrusion.