A multidisciplinary study of a geothermal reservoir below Thisted, Denmark

The first geothermal plant in Denmark was established in 1984 near the town of Thisted (Fig. 1). For nearly 30 years the plant has successfully produced c. 43°C hot water (surface temperature) from a highly permeable sandstone reservoir in the Late Triassic to Early Jurassic Gassum Formation and used the heat from the geothermal water for district heating. The 45°C hot water (formation temperature) is pumped up from a vertical production well, Thisted-2, from a depth of c. 1250 m and the cooled water (c. 12°C) is re-injected into the formation through a vertical injection well, Thisted-3, located 1.5 km east of the production well.