Kant Michael A., Ammann Jens, Rossi Edoardo, Madonna Claudio, HÃ¶ser Dragana, von Rohr Philipp Rudolf (2017), Thermal properties of Central Aare granite for temperatures up to 500°C: Irreversible changes due to thermal crack formation, in Geophysical Research Letters
, 44(2), 771-776.
Kant Michael Alexander, Meier Thierry, Rossi Edoardo, Schuler Martin, Becker Dustin, Höser Dragana, Rudolf von Rohr Philipp (2017), Thermal Spallation Drilling – an Alternative Drilling Technology for Hard Rock Drilling, in OIL GAS European Magazine
, 1/2017, 23-25.
Kant Michael Alexander, Meier Thierry, Rossi Edoardo, Schuler martin, Becker Dustin, Höser Dragana, Rudolf von Rohr Philipp (2017), Thermal Spallation Drilling – an Alternative Drilling Technology for Hard Rock Drilling, in OIL GAS European Magazine
, 1/2017, 23-25.
Kant Michael A., Rudolf von Rohr Philipp (2016), Determination of surface heat flux distributions by using surface temperature measurements and applying inverse techniques, in International Journal of Heat and Mass Transfer
, 99, 1-9.
Kant Michael A., Rudolf von Rohr Philipp (2016), Minimal required boundary conditions for the thermal spallation process of granitic rocks, in International Journal of Rock Mechanics and Mining Sciences
, 84, 177-186.
Höser Dragana Wallimann Roger Rudolf von Rohr Philipp (2016), Uncertainty Analysis for Emissivity Measurement at Elevated Temperatures with an Infrared Camera., in International Journal of Thermophysics, (2016) Berlin: Springer
, 37(2), 14.
Rothenfluh Tobias, Schuler Martin J., von Rohr Philipp Rudolf (2013), Experimental heat transfer study on impinging, turbulent, near-critical water jets confined by an annular wall, in JOURNAL OF SUPERCRITICAL FLUIDS
, 77, 79-90.
Kant Michael, A theory on thermal spalling of rocks with a focus on thermal spallation drilling, in Journal of Geophysical Research
Rothenfluh Tobias Schuler Martin Rudolf von Rohr Philipp, Development of a calorimeter for heat flux measurements in impinging near critical water jets confined by an annular wall, in The Journal of Supercritical Fluids
Among all sustainable energy sources geothermal energy seems to be an interesting candidate, because, unlike wind or solar energy, the energy production of a geothermal power plant is virtually independent of climatic conditions. However, to allow for installations of geothermal power plants independent of local geological conditions, ways to drill deep geothermal wells to competitive costs must be found. Costs of geothermal wells are commonly known to increase exponentially with depths , thus leading to drilling costs accounting for up to 70%  of the total costs of a geothermal power plant. The proposed follow-on project is aimed at contributing to the ambitious objective of reducing drilling costs by investigating a novel contact-free drilling technology by means of a flame jet in a thermodynamically supercritical water environment. This technology called “hydrothermal spallation drilling”  has a high potential of significantly reducing drilling costs mainly due to the absence of expensive drilling downtimes known from conventional rotary techniques, when worn-out drilling bits have to be replaced. The spallation technology is based on the characteristics of hard polycrystalline rock to disintegrate in small disk-like fragments when rapidly heated up by a flame jet. In all thermal spallation rock drilling experiments reported in literature only shallow holes up to 335m depth were drilled and constantly flushed with air to remove the cuttings . In deep drilling operation, however, the borehole is constantly filled with a water-based drilling fluid, which fulfils a lot of important tasks such as transport of rock cuttings, providing borehole stability or cooling and lubricating the drill bit. Hence, to apply this technology for the drilling of deep wells, a flame under high hydrostatic pressure and in an aqueous environment has to be operated downhole to produce a high-temperature supercritical water jet impinging on the rock’s surface. We have gained a great expertise on the operation of such “hydrothermal flames” burning in a supercritical water environment, since these flames have been extensively studied within the scope of supercritical water oxidation (SCWO) of organic substances (previous projects supported by SNF).A fundamental scientific investigation of the hydrothermal spallation drilling approach must include predominantly two important mechanisms: The mechanisms of heat transfer from a supercritical flame or water jet to the rock’s surface in an aqueous environment and the specific spallation properties of different rock types. Both mechanisms are going to be comprehensively investigated; whereas the first part of the proposed project concludes the extensive heat transfer studies carried out in the previous SNF-project, a step further is taken in the second part by focusing on the characterization of different rock types in terms of their spallation properties. The experiments in the first project stages are going to be conducted in the high-pressure plant HSDP-I already used in the previous project to complete the heat transfer study of a hot impinging supercritical water jet towards a flat plate by newly developed heat flux sensors. For the subsequent project stages a new ambient spallation drilling plant (ASDP-I) for alternative experiments with a rock sample and a heat flux sensor plate is going to be designed, constructed and commissioned. In this new plant, heat flux measurements to define fluid-side heat transfer characteristics will be performed to yield accurate boundary conditions for flame jet spallation experiments with rock probes. Thus, different rock types can be characterized in terms of their spallation properties. A straightforward research plan shows the realistic probability to reach the ambitious objectives.