WP5 - Meso-Scale Investigation

The objective of this work package is to achieve a most complete understanding of the water jet/tooling-rock-interaction for a large variety of sedimentary and crystalline rocks, in order to introduce a drilling technology for EGS that is not limited only to one single geological setting but will be applicable all over Europe in low to high enthalpy reservoirs. The reduction of risks for an insufficient connection of the borehole to the reservoir will remain the major challenge for the geothermal industry worldwide. Thus, it is necessary a) to prove the existing water jet-technology for different rock characteristics in laboratory and field scale experiments, b) to detect and understand the gaps, c) to improve the design when possible, d) to investigate if additional information about the geological structure is obtainable while drilling and finally e) to iteratively develop an enhanced jetting technology for rock properties that the existing water jet-tooling is not applicable to.

By following these general objectives a number of more specific goals have to be tackled. For determining the variety of the physical – (geo-) mechanical, pressure-/temperature-related, hydraulic – influences on the drilling processes a set of experiments needs to be conducted. Those tasks will be realized under laboratory and reservoir conditions, such as:

  1. Rock sample collection and characterization in cooperation with WP4;
  2. Laboratory experiments under atmospheric conditions to prove the existing water jet-technology for sedimentary and crystalline rocks;
  3. Large scale laboratory experiments to establish the existing water jet-technology at simulated reservoir p/T-conditions for selected rocks (in-situ Borehole & Geofluid Simulator Device);
  4. Improvement of the water jetting technology set-up and design in accordance to the results of the lab-experiments;
  5. Testing the existing water jet-technology in a meso-scale experiment in a quarry;
  6. Development of an enhanced - abrasives/mechanically assisted – water jet/drilling device for heterogeneous, very hard rocks.