Interpretation and simulation of the Hamar geothermal field, N-Iceland

Abstract

The Hamar reservoir is one of many low-temperature geothermal fields in Northern Iceland. Since 1966 eleven wells have been drilled in the field but at present only well 11 is producing. About 44 temperature logs were taken from 1966, and water level changes and production rates have been recorded since 1975. Well tests were performed in 1988. On the basis of these data, the thermal characteristics of the reservoir were analyzed, and the main aquifers or feedzones identified. The hot water recharge comes from the south. After most of the wells were cased and/or cemented in 1990, the temperature in the reservoir has remained constant. The physical behaviour of the reservoir was simulated using a lumped parameter model. Water level changes with various production rates for the next 20 years are given. Analyses of well test data from the reservoir were made using Theis solution and Horner methods. The same results were obtained using both methods. The reservoir has a transmissivity of about 5.5×10-7 m3/Pa s, coefficient of storativity (cth) of about 7.5×10-8 m/Pa and a calculated reservoir thickness (h) of about 1500 m.