Temperature Model and Volumetric Assessment of the Krafla Geothermal Field in N-Iceland

In 2008 the conceptual model of the Krafla geothermal field was revisited by a large group of scientists from various disciplines considering a range of new data. The new conceptual model confirms the large scale understanding of the reservoir mechanism but has provided a great increase in knowledge about the detailed structure of the reservoir. In connection with the development of a new conceptual model, geological, geochemical, and geophysical data from the Krafla geothermal field have been compared using the PETREL software. Estimated formation temperature has been used to form a 3-D temperature model for the studied area which forms the basis for a new volumetric assessment of the geothermal system. The most important factor in the volumetric assessment is an estimation of the volume of the geothermal system. Resistivity data is used to determine the maximum surface area of the system and how the temperature is distributed within the estimated volume of the geothermal area. Other reservoir parameters and their uncertainties are determined on the basis of the recently developed conceptual model and volumetric calculations are carried out using the Monte Carlo method. The volumetric assessment is calculated with two different temperature estimation schemes. (1) With the traditional method of assuming that the temperature only changes with depth and (2) by constructing a 3-D temperature model of the system. The estimated production capacity of the geothermal field is similar for the two methods. This supports the method and suggests that in general the simpler model gives a fairly good estimate of the production capacity.