| Title | Managing the Production Fields in the Hengill Area |
|---|---|
| Authors | Gunnar GUNNARSSON, Sigrún TÓMASDÓTTIR, Simon KLÃœPFEL, GÃsli Björn BJÖRNSSON, Ãsgeir WESTERGREN |
| Year | 2020 |
| Conference | World Geothermal Congress |
| Keywords | Hellisheiði, Nesjavellir, Hengill, reservoir management, reservoir modelling, make-up drilling, reinjection, economic feasibility |
| Abstract | The Hengill Central Volcano, SW-Iceland, contains widespread geothermal resources. Due to its proximity to ReykjavÃk those resources are of high importance for space heating in ReykjavÃk and surrounding communities and for electricity generation. ON, a subsidiary of Orkuveita ReykjavÃkur (Reykjavik Energy) operates two co-generation power plants in the Hengill Area; Hellisheiði in the southern part of the area and Nesjavellir on the northern flank of the Hengill Volcano. The current installed capacities of the power plants are 303 MW in electricity and 133 MW thermal for Hellisheiði and 120 MW in electricity and 290 MW thermal for Nesjavellir. The Nesjavellir Power Plant was commissioned in six phases in the years 1992-2006 and the Hellisheiði Power Plant in four phases in the years 2006-2011 and its production field was expanded in 2016. The production density in the field is high or approximately 220 kg/s/km² (or 50 MW/km² in electricity) in the most productive part of the Hellisheiði Field. The production density in the most productive part of the Nesjavellir Field is similar. It is complicated to operate a geothermal field with such a high production density. In order to maintain reservoir pressure geothermal brine is reinjected into the reservoir and for maintaining production capacity make-up wells are drilled. Proper management of the fields requires being able to predict how the above mentioned measures affect the geothermal reservoir. To aid with decision making in the development and production from the geothermal fields in the Hengill Area, a numerical model of the entire Hengill area has been developed. It has been used to study the feasibility of different production scenarios and their impact on the geothermal reservoir. The model is constantly beeing revised, and has been a key tool in the decision-making process for recent and future developments of the fields. Make-up drilling schemes and different reinjection schemes have been simulated. Building on those simulations, the economic feasibility of technically sound production scenarios has been estimated. |