Injection test and early production history of well THG-1 at Theistareykir geothermal field, N-Iceland

Abstract

The Theistareykir field is located in the volcanic rift zone in N-Iceland and has abundant geothermal surface manifestations. One of the wells in this area, THG-1, was vertically drilled. After completion of the well, THG-1 was tested for its pressure response to step injection. The data were analysed by using the computer programs WellTester and Lumpfit. The skin factor for the well is estimated to be around -2, the transmissivity of the surrounding formations around 2×10-8 m3/Pa·s, and the formation storage about 2×10-8 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 the locations of possible aquifers in the well were determined. Two main and two minor feed zones are seen in the well. The formation temperature was evaluated, but the best result for the formation temperature was obtained by using the last static temperature profile measured before flow commenced in the well.