System properties at process conditions


The Institute of Subsurface Energy of Clausthal University of Technology is working on the project “Optimized mud driven drilling hammer for hard formations in geothermal wells”, abbreviated OBH, which is financed by the Federal Ministry for Economic Affairs and Energy. Its aim is the development of a hammer tool, which guarantees higher rate of penetration and consequently reduced drilling costs in hard formations in comparison with common drilling methods. It is proven, that a crushing material removal generates a much more effective drilling process than a scraping or cutting action, when granite, gabbro or gneiss is forming the foundation.

At the moment, it is no down-the-hole hammer tool known, which can be reliable used under the same conditions like pure rotating drilling methods, i. e. with drilling mud, common filtration processes and normal BHA components. Therefore, a mud driven drilling hammer in 6 ¾’’ is currently being developed at the Institute of Subsurface Energy. The energy of the mud is directly been used, no secondary circuit or another energy transformation is necessary.

An important aim of the project is to guarantee the compatibility with conventional drilling systems. Calculations and Experiments with common mud pulse telemetry systems will be done and a directional drilling device will be implemented. A secondary aim is the engineering of a shock dampening system to reduce mechanical impacts on following drill string components.


P. Jaeger, R. Eggers: Interfacial properties at elevated pressures in reservoir systems containing compressed or supercritical carbon dioxide, J. Supercrit. Fluids 66 (2012), 80– 85.