A Combined Regional Conceptual and Supercritical Numerical Model of the Reykjanes Peninsula

Abstract

Conceptual and numerical modelling have become invaluable tools in exploring, developing and operating geothermal fields. This study investigates a workflow where a 3D conceptual model of the Reykjanes peninsula is directly used in to create a new supercritical numerical model. The Reykjanes peninsula is located in South-West Iceland and is the landward extension of the divergent plate boundary of the mid-Atlantic ridge. It is home to three geothermal systems namely Reykjanes, Eldvörp and Svartsengi, two of which are being utilised. A new 3D regional conceptual model of the Reykjanes Peninsula has been developed to a depth of 6km utilising the LeapFrog Geothermal software package. The main geological units included in this regional model are based on findings from the IDDP activities in the Reykjanes geothermal field which confirmed the presence of ophiolite in the roots of the reservoir. LeapFrog was then directly used to generate a new supercritical AUTOUGH2 model. The model was calibrated by adjusting the depth of the 500 degc isosurface within the hot sheet dyke complex of the conceptual model. This ophiolite has proven temperatures in excess of 400 degC. A workflow was executed which made use of the natural feedback loop between the conceptual model and the numerical model in LeapFrog. The numerical model has been calibrated to measured conditions at the Reykjanes, Eldvörp and Svartsengi geothermal systems and provides a useful tool in understanding the super critical conditions in the roots of the geothermal reservoirs.