Geochemical Monitoring and Tracer Tests in the Reykjanes Production Field

Abstract

Geochemical monitoring has been conducted in the Reykjanes field since the first production well was put online in 1970. It became more extensive after the commissioning of the 100 MWe powerplant in the spring of 2006 which dramatically increased the production of the field. In this paper chemical monitoring of the dissolved solids especially chloride in relation to the inter-well tracer tests conducted will be presented. The Cl concentrations since 2012 indicate that a boiling trend which was observed in previous years has stopped or reached an equilibrium, as Cl concentrations in wells have not increased although some fluctuations are seen. Nonetheless, the recent Cl concentrations from some of the wells are higher than the concentrations measured before commissioning of the power plant. Many of those wells have Cl concentration higher than that of seawater. Chloride concentrations in many wells have been decreasing in recent years. It is likely that the decreasing Cl concentrations in some of the wells may be attributed to dilution with the reinjected liquid. Tracer tests conducted in the field also confirm the feedback between the brine and condensate mixture re-injection and freshwater injection and the deep fluid chemical composition.