Table of Contents
Application of fiber lasers in geothermal drilling
A high-power fiber laser has been successfully tested in field trials to weaken hard rocks to increase efficiency and reduce the cost of geothermal drilling. The fiber laser technology promotes a process applied to access geothermal heat, a clean and sustainable energy source.
Challenges in deep-earth drilling
When drilling deep into the earth’s crust, the drill bit’s temperature rises by approximately three degrees Celsius for every 100 meters, and upon striking hard rock, the drill bit experiences more rapid wear, leading to a reduction in its penetration speed.
Costs and research motivation
The cost of this process is high and often prevents investors from continuing with deep geothermal projects. Therefore, a group of researchers from Germany developed a method for mechanical drilling of hard rocks employing a laser system.
Design and operation of the fiber laser system
This fiber laser system can not only increase the penetration rate in geothermal drilling but also help to maintain the cutting edge of the drill bit by loosening and even breaking the rock just before drilling begins.
Technical specifications
The researchers have developed this laser system by initially installing a test unit with a ytterbium-based fiber laser with an output power of up to 30 kilowatts, which they then used to successfully loosen sandstone, granite, and quartzite. All these materials are solid rocks with a strength of more than 150 megapascals, up to 80 percent.
Laser guidance and safety
A jet of water is used to direct the laser beam to the rock surface – similar to how an optical fiber can direct a laser system— which also prevents contamination and damage to sensitive fiber laser optics and makes it easier to remove rock fragments with a drilling tool.
Field testing and future improvements
Then the engineers use a fiber laser system on the rig in a specially designed drill string and test the new tool in real-world conditions in field tests, which also proved successful. In future projects, the researchers plan to further improve the laser beam power distribution and add digital sensors to the hybrid tool to get feedback from the drilling process and thus be able to respond to material changes on the drilling path.
Advantages and potential impact
The flexible adjustment of the laser beam output power is one of the factors that make it a particularly effective tool for facilitating drilling processes. According to the researchers, the developed powerful fiber laser system will help reduce the cost of deep geothermal drilling in the future and simplify the use of geothermal energy as an inexhaustible source of energy-supporting other renewable sources such as sunlight, wind, and water.