Fraunhofer Research Institution for Energy Infrastructures and Geothermal Systems IEG
In the geotechnology laboratory, experiments and analyses can be carried out on samples ranging in size from decimetres to metres. The infrastructure of this laboratory acts as a link between the laboratory and field scales and enables the gap to be closed for scaling findings from the Geoscience laboratory to the field scale. The central component of the laboratory is the match.BOGS (match-"borehole and geofluid simulator"), which makes it possible to physically simulate processes relevant to the careful development and sustainable use of geogenic resources under in-situ conditions. For this purpose, match.BOGS consists of three interlinked modules: i.BOGS, drill.BOGS and fluid.BOGS. The i.BOGS ("i" for "in-situ") represents an autoclave capable of exposing rock samples 3 m long and 25 cm in diameter to triaxial pressure and temperature conditions of depths up to 5 km (1250 bar and 180 °C). Alternatively, technical components such as pumps or measuring instruments can be tested and operated through special feedthroughs into the autoclave. Flow through the autoclave - even with corrosive fluids - is possible at a flow rate of up to approx. 10 l/s. Acoustic, optical and thermal sensors help to detect and quantify processes that are taking place. The drill.BOGS ("drill" for "drill drive") is the trainer's drill drive. It makes it possible to drill into the rock sample under reservoir conditions inside the i.BOGS using various drilling tools. Two hydraulic cylinders provide the necessary feed force of up to 400 kN. The continuously adjustable electric motor drives the drill rod with up to 12 kNm of torque. The installed measurement, control and regulation technology (MCR) enables fully automated drilling operations to be carried out with changing rock properties. By means of the fluid.BOGS ("fluid" for "fluid reactor"), synthetically produced geothermal fluids with a defined composition are to be provided on a pilot scale at controlled temperature, pressure or mass flow. These geofluids can be fed into the i.BOGS under pT reservoir conditions to study stimulation or flow-through processes in the reservoir or downhole. A flow loop within the fluid.BOGS will ensure precise control of all parameters.
The match.BOGS infrastructure will be complemented by smaller autoclave systems in which various hydraulic and mechanical drilling processes will be further developed on rock samples in the decimetre range at pressures up to 600 bar.
