The Ruhr Metropolitain Underground Laboratories (MULE) at Bochum is a large-scale facility for technology development for the changes of energy systems in urban areas. MULE has a 50 km2 geothermal mining permission with a test site right in the center of one of the largest European urban areas. The test plant shall study the effects of the injection of hydrothermal fluids enriched with CO2 into a low temperature sedimentary reservoir.
It will consist of a dual flow and injection system (400 l/Min) with a closed flow-loop reactor and two 500 m wells. Emissions are controlled by an array of monitoring wells for induced chemical, hydraulic, thermal/fibre optic, seismic effects. Using MULE as GECO demo site, the Bochum Geothermal Centre is aiming at studying the effect of CO2 injection on the sandstone formation for further injection experiments.
The German demosite is situated within the city of Bochum, which is located in the center of the Ruhr Coal District and the municipality belongs to the state North-Rhine Westphalia. The Ruhr coal basin is part of the external fold and thrust belt of the Variscan orogeny in Central Europe. Sedimentary rocks in this region represent mostly the molasse-type sequence of the Upper Carboniferous, basically formed by interlayered sandstones, siltstones, mudstones and coals, with a thickness of more than 6000 m. The Variscan orogenic belt in Western and Central Europe was formed during the Late Palaeozoic convergence of the Euramerican (Laurussia) and Gondwanaland continental masses.
The convergence and collision took place during the Devonian and Carboniferous, with the deformation front migrating northward with time. Sedimentation concurrent with deformation in its surroundings formed the Variscan foredeep and foreland basin, which marks the Ruhr basin of today. The Ruhr basin strikes in southwest-northeast direction and has a length of 150 km and a width of 80 km across the strike. The demonstration site is located within a syncline, that contains a sedimentary sequence that belong to the Bochum and Witten strata. The study area is crosscut by a fracture system that represents the dominant permeable structures.
Geology, Reservoir Properties
The GECO technologies at the Kızıldere site include:
History of the site
The aim of the German contribution to the GECO project is to investigate the absorption behaviour of CO2 in sedimentary rock in urban environments. Fraunhofer IEG in Bochum, where the GECO demo site is located, hosts a unique laboratory and test sites equipment for fundamental and applied research. The test site represents a 10.000 m² drill site with existing research, observation and production wells and allows drill tests for advanced technology.
The Fraunhofer IEG site underground Laboratories will be implemented for the GECO project by drilling a new well and by building a FGR (Fluid-Gas Reactor) including a CMS (Corrosion Monitoring System).
The experiments involving the FGR can be divided into three parts: The ex-situ experiments using the I-Bogs, the in-situ experiments using the injection and production wells, and the corrosion monitoring using the CMS. All of these experiments will take place at the drill site at the IEG.
For the GECO injection experiments the FGR device will be connected to an open hydraulic circulation loop system with 2 boreholes.