Geothermal assessment of the Glerardalur and Svartsengi fields

Abstract

The methods for assessment of geothermal resources are reviewed. Assessment are made for the resources of two geothermal fields by the volumetric and the modelling methods. One of the fields is the Glerardalur low-temperature geothermal field in N-Iceland. The resource base is estimated to be 1.51×1015 kJ by the volumetric assessment. The extractable quantities are 3.85×1012 kJ for the closed system and 1.7×1014 kJ for the recharged system, respectively, under the specified exploitation methods. In the lumped parameter model, calibration and verification were conducted with data accumulated over 10 years observation of the reservoir response to production. The obtained parameters were used for predicting the reservoir response to different constant production rates over the next 15 years. The present trend of stabilized drawdown can be maintained only for an annual average production rate not larger than 15 l/s. The other field is the Svartsengi high-temperature geothermal field in SW-Iceland. The reservoir was divided into upper and deeper parts for the volumetric assessment which estimated the resource base as 9.87×1015 kJ. The extractable quantities are 2.53×1015 kJ for the closed system and 3.76×1015 kJ for the recharged system, respectively, under the specified exploitation methods. In the lumped model, the calibration and verification were conducted with data accumulated over 14 years observation of reservoir response to production and on the results of geological and geophysical surveys. The model obtained was used to predict reservoir response to different constant production rates over the next 15 years. The optimum production rate is estimated to be slightly less than 200 kg/s.