Sequential reservoir treatment at natural fracture zones in deep-seated carbonate rock to develop a petrothermal site in Germany

The aim of the joint research project ZoKrateS is to prove the hydraulic effectiveness of proppants that have not previously been used in deep geothermal reservoirs. In combination with zoned acidification, these proppants should be injected into naturally open fracture zones of deep-lying carbonates; this shall serve the development of a petrothermal site in Germany. The research work of the LIAG has its focus in sub-project B: Planning, seismological monitoring and knowledge transfer.

The name ZoKrateS originates from the project title “Sequential reservoir treatment at natural fracture zones in deep-seated carbonate rock to develop a petrothermal site in Germany”. The joint partner of this project are Ruhr Universität Bochum, GTN, G.E.O.S. and ENEX.

The research project "ZoKrates" is a demonstration and pilot project to evidence the technical feasibility and improvement of the hydraulic connection of a well to a fracture controlled reservoir for geothermal utilization by in-situ testing in a deep well. In this case, a hydraulically conductive fracture zone, which has already been drilled by the deep well GEN-1ST-A1, shall be used a natural heat exchanger, so that the hydraulic stimulation is avoided and the risk of induced seismicity is significantly reduced. The aim of the research project at the Geretsried site (Bavaria) is to demonstrate the hydraulic effectiveness of proppants that were previously not used in deep geothermal energy projects. In combination with sequential reservoir treatment, these proppants will be injected into natural fracture zones of deep carbonates, with the aim to develop a petrothermal site in Germany. With regard to the selection of suitable proppants, in particular the safety of the use of proppants from an environmental point of view is of particular importance. The joint project "ZoKrates" consists of scientific and economic partners, among which is the field owner. The partners are Ruhr University Bochum, Leibniz Institute of Applied Geophysics, GTN, G.E.O.S. and ENEX.

The work plan covers the aspects of (I) the hydraulic connection and geothermal use of natural fracture zones, (II) the use, testing and assessment of suitable proppants for keeping open the fractures in the near-wellbore region, where the largest pore pressure reduction occurs during production, (III) hydraulic tests with proppants serve to identify future drill paths by simulations of petrothermal doublets in fault intersection zones. The following tasks shall be worked out in seven work packages to achieve the project goals: (i) revaluation of the existing data, planning of the reservoir treatment, material evaluation; (ii) mechanical material tests in the laboratory, selection of suitable proppants, calculation of a Mechanical  Earth Model; (iii) reservoir engineering, sequential reservoir treatment simulation, THM model of a petrothermal doublet; (iv) reservoir treatment in the borehole GEN-1ST-A1; (v) seismological monitoring, risk analysis, INSAR measurements; (vi) data synthesis, economic analysis of a petrothermal system for heating purposes; (vii) public relations, data provision in GeotIS.


Ruhr-Universität Bochum

Geothermie Neubrandenburg GmbH

G.E.O.S. Ingenieurgesellschaft mbH




Duration: 01.01.2020 - 31.12.2021