Wednesday, December 2, 2015

Science & Technology: New Process Uses High Voltage for Deep Geothermal Drilling

Drilling like lightning (IDW)

95% of the geothermal water resources in Germany are situated in crystalline rock. Existing drilling methods, however, are only able to advance slowly though this hard rock and the drill bits wear out quickly. The BINE Projektinfo brochure “Electric impulses fragment hard rock” (13/2015) presents an alternative drilling procedure. Here, a high-voltage impulse fragments the rock. This method causes little wear to the drill bits and enables up to 30% lower drilling costs.

When drilling with the electric impulse process (EIP), two electrodes are positioned below ground on the rock layer. Through them, 400-kV impulses are shot into the rock. In the impulse’s breakdown channel, the pressure and temperature within the rock increase and the rock breaks up. The resulting drill cuttings are removed by a non-conductive drilling fluid. The EIP drill bit has been successfully tested on a test stand under wellbore-like conditions. The aim of the ongoing follow-up project is to develop a complete drilling system and to test it in a real borehole.

Scientists at Dresden University of Technology are developing the EIP drilling system in collaboration with industrial partners. Drilling work can account for up to 90% of the investment costs in geothermal projects. Each technical improvement and cost reduction in the drilling process therefore brings new geological heat reservoirs within economic reach.

More information about the BINE Projektinfo can be found in the brochure “Electric impulses fragment hard rock

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