Temperature distribution and simulation of the Bodmodsstadir geothermal field in southern Iceland

Abstract

The Bodmodsstadir geothermal field is one of the low temperature geothermal fields located just outside the neovolcanic zone in southern Iceland. Ten wells have been drilled in this area since 1974. Well BS-1 is the only producer and the water from it is used for greenhouses and space heating at the Bodmodsstadir farm. The formation temperature distribution in the area, the location of aquifers and a conceptual model of the geothermal field are presented in this report. This study is based on temperature logs, water level measurements and pressure in the wells and other geological and geophysical data. To further develop the model of the Bodmodsstadir geothermal system, both steady-state and non-steady-state simulations were performed. When assuming a fracture situated between wells BS-2 and BS-10, dipping 8 and striking N40 E in the steady-state simulation, the calculated temperature distribution matches well the observed temperature in the wells. The non-steady-state simulation indicates that it took about 5000 years for this system to reach quasi-steady-state (natural state). Furthermore, when solving both the mass and the energy transport equations in the non-steady-state simulation, the recharge rate from depth has to be in the range of 1-10 kg/s, with permeability of the fracture between 0.1-0.8 Darcy to match the observed temperature data. The natural state model developed in this study could be used to evaluate this geothermal system and for planning its development.