Reservoir parameters for well HE-5, Hellisheidi Geothermal field, SW-Iceland

Abstract

The Hellisheidi geothermal field is located within the Hengill high-temperature area in SW-Iceland. One of the wells in this area, HE-05, was directionally drilled. After completion of the well, HE-05 was tested for its pressure response to step injection. Data was analysed by using type curve matching and semi-log analysis. The skin factor for the well is estimated to be around -6, the transmissivity of surrounding formations around 2x10-4 m3/Pas, and the formation storage about 6.4x10-8 m/Pa. Temperature and pressure profiles measured in the well during injection, warm-up and discharge were evaluated; and the formation temperature, initial pressure conditions in the vicinity of the well, and locations of possible aquifers in the well were determined. Two main and two minor feedzones are in the well. Formation temperature was evaluated, but the best result for formation temperature was obtained by using the last static temperature profile measured before flowing the well. A wellbore simulator was used to model the well during discharge and the results suggest two feedzones in the well. In addition, the wellbore model was used for prediction of pressure drop in each feedzone to estimate the flow conditions in the well. A production test showed that the capacity of this well for power generation is 3-4 MWe. The locations of the main feedzones, and the temperature in the lower part of the well agree with the current conceptual model for the Hellisheidi field.