In 2003, two deep geothermal wells for a geothermal dublet were drilled on the site of the former airport, today´s site of the exhibition center Riem. The aim of the project was to replace the base load of the heat supply (8 MW) in the district Munich-Riem, covered by natural gas, with hydrothermal energy. The realization of this demanding project started with the construction of a multipad well site (6,000 m2) on the adjacent site of the existing heating plant. The distance between the two wells on the surface is only 15.5m. The two wells are deviated assymmetrically to NNW and SSE to produce thermal water from the Malm-Carbonates of the Jurassic from depths ranging from 2,600 to 3,000 m. The geological and drilling conceptual planning was based on reflexional seismicity data and detailed analysis of adjacent exploration wells. Through the insights made during the planning, two different types of reservoirs were identified: A fault zone for the NNW directed well and an undisturbed part of the SEE- plunging Malm-Aquifer.
The well Th1 reached its final depth after 42 days with a measured depth of 3,275m, which is equivalent to a vertical depth of 3,019m. The Malm-Aquifer was tapped over 488 m with a final bore diameter of 6.1/8" (156 mm).
The success of the project was confirmed after a successful acid stimulation and a short-term pumping test. Due to the great depth of the main production horizon, the temperature of the thermal water was even higher than expected (92.8 °C).
The geological knowledge gained was useful for the drilling of the well Riem Th2, which reached a final measured depth of 3,225 m (2,747 m TVD = True Vertical Depth). The directional drilling lead to a distance of 2,200 m between the two end points of the wells. The testing for the Th2 delivered a temperature of 93 °C and a flow of 40 l/s accompanied by a pressure reduction of 4 bar.
The total costs of the project amounted to €5.3 m. including the costs for recultivation of the well site. Despite the greater depths of the wells, the total costs were lower than the project’s budget. At the moment, the submersible centrifugal pump is able to produce 75 l thermal water per second at a temperature of 94 °C. After heat is partly extracted it is reinjected into the Malm-Aquifer.
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