A new Apparatus for Long-term Petrophysical Investigations on Geothermal Reservoir Rocks at Simulated In-situ Conditions

We present a new apparatus capable of maintaining in-situ conditions pertinent to deep geothermal reservoirs over periods of months while in the same time allowing a variety of continuous petrophysical investigations. Two identical devices have been set up at the GFZ-Potsdam. Lithostatic overburden- and hydrostatic pore pressures of up to 100 and 50 MPa, respectively can be simulated. In addition in-situ temperature requirements of up to 200°C can be met. The use of corrosion resistant parts throughout the pore pressure system allows investigations with highly saline formation fluids. Rock permeability, electrical conductivity as well as compressional- and shear-wave velocities can be measured simultaneously and the pore fluid can be sampled under pressure for further chemical analysis. Scientifically, the usage of the device focuses on risk potentials in exploration and exploitation of deep geothermal reservoirs. Particularly, the investigations address possible effects of fluid-rock interactions on the transport properties of a reservoir host rock.