Geologists and engineers have successfully drilled into the heart of a volcano in Iceland, as part of a project aimed at assessing the economic feasibility of using deep unconventional geothermal resources to deliver renewable energy.
Drilling so deep into such a hot borehole poses many difficulties, but if researchers manage to overcome the challenges, fewer geothermal wells would need to be drilled in the future because the energy content of fluids so deep into the ground is much higher than conventional geothermal steam.
The Deployment of deep enhanced geothermal systems for sustainable energy business (DEEPEGS), funded under the EU’s Horizon 2020 program, considers unconventional geothermal resources as those that are superhot, up to 550 degrees Celsius (1,022 degrees Fahrenheit), and very deep—more than 3 kilometers (1.864 miles).
Earlier this year the Iceland Deep Drilling Project (IDDP) at the Reykjanes Peninsula in Iceland completed drilling at a depth of 4.659 kilometers (2.9 miles) where it recorded temperatures of 427 degrees Celsius (800.6 degrees Fahrenheit).
The drilling, which began in August 2016, created the deepest volcanic borehole ever. Geologists and engineers aim to find if the so-called supercritical fluid—a condition in which water is so deep in the ground that it is neither liquid nor gas—can be used for efficient energy production.
Supercritical fluid has a much higher energy content than conventional high-temperature geothermal steam, scientists concur, but drilling so deep into the heart of a volcano is difficult to achieve and control.
According to the project’s partners, this drilling project could result in the opening up of new areas for geothermal energy utilization and the enhancement of the performance of current production zones in Iceland. If supercritical wells are able to produce more power than conventional geothermal wells, less drilling of geothermal wells would be needed around the world, which would lead to “less environmental impact and improved economics,” the project partners say.
However, a lot more research, testing, and flow simulation will be needed, and the final results on the technology and economics of production from the well will not be known until the end of next year at the earliest.
“The purpose of the IDDP-2 project is research and the drilling completion is only one phase of the project. The next steps will be to do further testing and research on the well, and most importantly flow tests and fluid handling experiments will be conducted within the next two years,” said the partners, which include Norway’s oil major Statoil.
The next stage of the project involves pumping cold water into the well, which will open it up in order to tap into the steam at the bottom to provide a source of geothermal energy.
Naturally, drilling such a deep and hot well poses many difficulties, according to the project partners. They claim that “using conventional drilling methods was not an option for many aspects of the project so new methods had to be developed to ensure the progress of the project”.
The drilling had many challenges to overcome, but the major unsolved problem was a complete loss of circulation below 3 kilometers (1.864 miles) of depth, and that “could not be cured with lost circulation materials, or by multiple attempts to seal the loss zone with cement”.
It’s not by chance that Iceland is the site of the deep geothermal drilling project. In the island country with population of just over 300,000, geothermal power facilities generate 25 percent of the total electricity production, according to Iceland’s National Energy Authority.
Although it is home to just over 300,000 people, Iceland makes the top 10 of ‘geothermal countries’ list by ThinkGeoEnergy with 665 MW of installed capacity. The U.S. leads the world in terms of electricity generated from geothermal energy in absolute figures, with California providing 74 percent of the U.S. geothermal electricity in 2015.
By Tsvetana Paraskova for Oilprice.com
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