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Successful trials on high-power laser to crumble hard rock for geothermal drilling

Drill bit of laser drill string with exiting laser water stream (Source & Copyright Fraunhofer IPT)
Alexander Richter Alexander Richter 26 Jan 2019

A group of German and Swiss researchers are reporting on successful trials of LaserJet Drilling, a method for laser-assisted mechanical drilling in hard rock, that could revolutionise drilling for geothermal and likely oil/ gas as well.

Research institute Fraunhofer Institute for Production Technology IPT in Aachen Germany reports on research done on high-powered laser for drilling.

Drilling deep into the earth’s crust, the temperature on average rises by about three degrees Celsius per 100 meters. However, with deep geothermal wells, the drills encounter different materials, including hard rock. These can only be drilled with low advance rates and wear out the drill bit faster. This leads to high costs, which often prevent investors from actually implementing geothermal projects. The Fraunhofer IPT has therefore, together with partners in the research project “LaserJetDrilling”, developed a method for laser-assisted mechanical drilling in hard rock and successfully tested it in field trials.

We assume that these research efforts are similar to that done by a U.S.-based company called Foro Energy, we reported on that a while back. The company received around some research funding under the ARPA-E program in the U.S. back in the days.

According to Fraunhofer, in the newly developed process, the researchers supplemented the mechanical drill with a high-power laser, whose energy is guided onto the rock by means of a jet of water. Thus it is possible to weaken the material immediately before the drilling process and to facilitate the mechanical removal with the drilling tool. The water jet not only guides the laser beam down to the rock, but also prevents contamination and damage to the sensitive laser optics.

In order to increase the rate of advancement of the drill bit and to protect its cutting edge, it is necessary to introduce additional energy into the borehole. Since with increasing depth of drilling different and often unpredictable materials must be processed, the laser is particularly suitable as a tool due to the flexible adjustment of performance.

Successful tests of the hybrid tool

The researchers from Aachen have set up a test stand in the machine and tool hall of the Fraunhofer IPT with a laser and a cutting tool that can achieve a light output of up to 30 kilowatts. In laboratory experiments, the project partners tested the process and made preparations for its transfer to the real application: The hard stones sandstone, granite and quartzite with a strength of more than 150 megapascals were weakened up to 80 percent by the laser.

In the next step, the engineers used the laser on the drill rig in a specially developed drill string and successfully tested the new tool together with the International Geothermal Center Bochum in a field trial under realistic conditions.

In future research projects, partners want to better distribute laser power and add digital sensors to the hybrid tool to get feedback from the drilling process to better respond to changes along the borehole.

Cost-effective geothermal wells for the production of renewable energy

The powerful drilling system can reduce the cost of deep geothermal wells and harness geothermal energy as an inexhaustible source of energy. This form of energy can take over part of the base load in the energy mix and complement other renewable sources such as the sun, wind and water compared to fossil fuels and nuclear energy comparatively environmentally friendly and low-risk.

Project consortium

Fraunhofer Institute for Production Technology IPT, Aachen
GZB International Geothermal Center Bochum e.V.
Herrenknecht Vertical GmbH, Schwanau
IPG Laser GmbH, Burbach
KAMAT Pumpen GmbH & Co. KG, Witten
Synova S.A. (Associate Partner), Duillier, Switzerland
The research project LaserJetDrilling was funded by the Federal Ministry for Economic Affairs and Energy BMWi and supervised by Projektträger Jülich (grant number: 0325784A).

Source: Press Release by Fraunhofer IPT