No abstract

For the geothermal project "Waldkraiburg" a well doublet was installed for district heating. The study area is located in the rural district of Mühldorf am Inn in Upper Bavaria, some 60 km east of Munich. Due to the intensive exploration activities of the petroleum and gas industry the geological structure of the subsurface is relatively well known.Two deviated drillings, WKB Thermal 1 with a length of 2,839 m MD (2,720 m TVD), and WKB Thermal 2 with a length of 3,360 m MD (2,620 m TVD), were sunk into the fractured limestone-dolomite aquifer (Purbeck-Malm). The distance between the drillings at top aquifer amounts to 2,150 m. The evaluation of the hydraulic tests yields an aquifer transmissivity of 4 to 6x10 -4 m 2 / s, and an aquifer thickness of 288 m. The fractured net thickness of the aquifer in WKB Thermal 1 amounts to 53 m (50 % in dolomite) and in WKB Thermal 2 to 44 m (77 % in limestone). The temperature of the minor mineralised water (c= 720 mg / l) at the well head is 106 °C. The temperature at the final depth of the wells corresponds to a geothermal gradient of 4.1 K / 100 m. The basal heat flux at the top of the crystalline was estimated to be 0.097 W / m².Based on the drilling data, on the geological profiles of the boreholes, and on the results of seismic investigations and structure maps, a 3D structural model was developed and implemented in a 3D flow and heat transport model.After calibration and validation, the model was used to simulate the expected 50-year-operation and the subsequent hydraulic and thermal regeneration of the aquifer. The simulation verified that at a production / reinjection rate of 65 l / s and a reinjection temperature of 50 °C no thermal influence in the production well is to be expected during the operating period.The range of the thermal influence (T > 1°C) in the middle of the aquifer around WKB Thermal 2 remains within a radius of 540 m. Temperatures at the reinjection site are expected to return to levels greater than 100 °C after a period of 2,300 years. Auf Basis von Bohrdaten, der Bohrergebnisse der abgeteuften Bohrungen, der Ergebnisse der seismischen Untersuchungen und der Strukturkarten wurde ein 3D-Strukturmodell des Gebietes erstellt und in einem 3D-Strömungs-und Wärmetransportmodell implementiert.Mit Hilfe des kalibrierten und validierten Modells wurden der 50jährige Betrieb und die anschließende hydraulische und ther mische Regeneration des Aquifers simuliert. Die Simulationsergebnisse zeigen bei einer Förderung von 65 l / s und einer Reinjektionstemperatur von 50°C keine thermische Beeinflussung der Förderbohrung während der Betriebsdauer. Der Wirkungsbereich der thermischen Beeinflussung (ΔT > 1°C) in Aquifermitte liegt um WKB Thermal 2 in einem Umkreis von r = 540 m. Eine Wiedererwärmung des Wassers über 100 °C ist nach ca. 2300 Jahren zu erwarten.

The coefficient of permeability (k value) is an important parameter in civil engineering practice, in hydrology and hydrogeology. It can be determined by field test or by means of laboratory testing. The goal of this paper is to assess this parameter by creating a laboratory model and by validating its results using finite element computer code. The model tests provide that can be applied for estimating permeability of different soils. In a physical model medium-grained sand was tested in the laboratory, for understanding the effects of different flow rates on the validation of the measurement result, the numerical simulation of the physical model was constructed using FEFLOW. Two model variants were developed and both variants were calibrated and validated. Subsequently, the results were converted to real variables based on the model laws. The physical model provides the flow rate of the well in medium-grained sand with sufficient accuracy if the real size of the drawdown is between 0,5 and 1,7 m.

No abstract

No abstract