| Title | Improving Thermal Water Production from Major Fault Zones by Combining Waterfrac and Subsequent Strong Reduction in Pressure |
|---|---|
| Authors | Wolfgang Herr and Peter Ruhm |
| Year | 2007 |
| Conference | European Geothermal Conference |
| Keywords | Fault zones, structures,stimulation, reduction in pressure, strong currents, scouring |
| Abstract | Deep reaching major fault zones respectively structures ("Tiefenstoerungen") hold a vast geothermal potential that is considered to exceed the geothermal potential of aquifers by a factor of four (Jung, 2002). This resource is virtually untapped in Germany, save one attempt in the 1980s at Bruchsal in the central part of the Upper Rhine Graben. It came out as a technical success and was ahead of its time. At present, with rising fossil fuel prices, an intense debate on climate change, and a growing interest in renewable energies, EGE thinks that attention should be payed to this reservoir type. A a new approach how to harness the potential of such fault zones is described. EGE plans to use waterfrac to stimulate specific parts of the structure in combination with periodic strong reductions in pressure (pulses). Strong hydraulic currents are created which periodically change their flow direction from the bore-hole into the rock domain and then back to the borehole. The applied forces will lead to scouring out channels, reactivating old fractures and fissures, and extract fine particles from the fault zone to the bore-hole from where they will be flushed out. The aim is to create a high permeability rock zone which surrounds the bore-hole. This zone will connect large volumes of medium to low permeability rock further away from the bore, thus setting the basic drainage system for high production rates. |