Hydraulic Stimulation Design for Well RV-43 on Geldinganes, Iceland

Abstract

The district heating system of the city of Reykjavik is almost exclusively fed by geothermal energy. Due to a growing population and increasing heat demand new heat sources need to be connected to the existing district heating network. One of the remaining potential geothermal systems with suitable conditions can be found on Geldinganes, an uninhabited peninsula within the city limits of Reykjavik. The only production well, RV-43, found the required temperatures, but not the necessary flow rates for economic heat production. Therefore, it is planned to develop this geothermal field by drilling new wells into potentially more permeable zones. Additionally, it is anticipated to hydraulically stimulate the existing well RV-43 in order to improve its hydraulic performance and to add additional production from this well to the heat network. Due to the location of the well within the city limits of Reykjavik, hydraulic stimulation treatments have to be designed to maximize the hydraulic performance increase while minimizing potential environmental risks such as induced seismicity. We provide an overview of the project including the site assessment, conceptual model, planned pre- and post-stimulation measurements, treatment schedule, zonal isolation and multi-stage injection concept, seismic monitoring network and procedures, and seismic risk assessment and seismic risk mitigation procedures, such as the cyclic soft stimulation concept and a site specific traffic light system.