The worlds hottest borehole is nearly complete

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Icelands Deep Drilling Project (IDDP), was founded in 2000 by a consortium of three Icelandic energy companies, who are now drilling deep into the heart of a volcano in the south-west of Iceland. Iceland, sitting on the boundary between two major tectonic plates, is one of the most volcanically active places in the world. The project is located on the Reykjanes peninsula, where a volcano last erupted 700 years ago.

In a discussion with the BBC on 14th of December 2016, researchers reported that in the next couple of weeks they should reach a depth of 5km, where temperatures are expected to exceed 500C (932F). That is the deepest level of drilling so far in the world.

Asgeir Margeirsson, CEO of the Iceland Deep Drilling Project (IDDP) in his interview with the BBC hopes that this will open new doors for the geothermal industry globally to step into an era of more production.

“That’s the aim – that’s the hope. We have never been this deep before, we have never been into rock this hot before, but we are optimistic.” Said Asgeir Margeirsson.

Harnessing this energy through geothermal technology is already well established in Iceland. In this area at Reykjanes, they typically drill to 2km or 3km depth to harness the steam, to run power plants and produce clean, renewable electricity as explained by Asgeir Margeirsson. They want to see if the resources go deeper than that.

The drilling has now reached nearly 4,500m, and the team expected it to hit its target depth of 5km by the end of the year 2016.

When the drill gets to 5km, the team expects to find molten rock mixed with water. But with the extreme heat and immense pressure found at this depth, the water becomes what is known as “supercritical steam”.

It is neither a liquid nor a gas, but it holds far more energy than either. It is this “supercritical” steam that the team wants to bring back up to the surface to convert into electricity.They believe its special properties mean it could produce up to 10 times as much energy as the steam from conventional geothermal wells. They don’t expect to drill into magma, but are drilling into hot rock which is around 400 to 500C.”

 

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Black basalt rock that has been collected from deep beneath the ground

Mr Margeirsson said that if this works, in the future they would need to drill fewer wells to produce the same amount of energy, meaning they would touch less surface, which means less environmental impact and hopefully lower costs.

“But that is if this works. This is full-scale research and development – we don’t know what the outcome will be.”  And there is a good reason to be cautious. With volcanoes, expect the unexpected.

Prof Freysteinn Sigmundsson, a volcanologist at the University of Iceland, reports that even though Iceland has more than 300 volcanoes, there is still much to learn about them. At the same time he states that this drilling project, however, would give geologists a unique vantage point to see the interior of a volcano.  He emphazises the importance of this project and the possible fundamental discoveries about how volcanoes work, learn about their properties and conditions.

The IDDP team says it is currently “drilling blind”, which means no rocky debris is coming back up to the surface. Instead, it is somehow being absorbed into the surrounding rocks.  Without being able to examine the rock, it means the geologists really are heading into the unknown.  However, with only a few hundred metres to go, they are optimistic that the world’s hottest borehole is now within their sights.

The IDDP project is funded by energy companies (HS Orka, Statoil, Landsvirkjun and Orkuveita Reykjavíkur), Orkustofnun (the National Energy Authority of Iceland), the International Continental Scientific Drilling Program (ICDP), the National Science Foundation in the US and EU Horizon 2020.

Iceland Deep Drilling Project (IDDP)

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The Iceland Deep Drilling Project (IDDP) is a long term study of high-temperature hydrothermal systems in Iceland. The IDDP is a collaborative effort by a consortium of three Icelandic power companies  (Hitaveita Sudurnesja (HS) (since 2008: HS Orka hf), Landsvirkjun (LV) and Orkuveita Reykjavíkur (OR)), and Orkustofnun (OS), the National Energy Authority of Iceland. and the Icelandic government, formed to determine if utilizing supercritical geothermal fluids would improve the economics of power productions from geothermal fields.

The IDDP expects to drill and test a series of boreholes that will penetrate supercritical zones believed to be present beneath three currently exploited geothermal fields in Iceland. One has been excecuted and the second will be activated in mid september 2016. A drilling to a depth of about 5 km will be required in order to reach hydrothermal fluids at temperatures ranging from 450°C to ~600°C.

A feasibility study completed in 2003 points at that in comparison to the output from conventional geothermal wells, which are 2.5 km deep, a ten-fold increase in power output per well could result if fluid is produced from reservoirs hotter than 450°C .

A typical 2.5 km-deep geothermal well in Iceland yields power to approximately 5 MWe. Assuming a similar volumetric inflow rate of steam, an IDDP well tapping a supercritical reservoir at temperatures above 450°C and at a pressure of 23-26 MPa may be expected to yield ~50 MWe.

The first IDDP drilling was performed in year 2009 in Krafla. The second drilling is scheduled mid september 2016 at the Reykjanes geothermal field. The aim is to drill 3 km deep. The drill Thor is powered by green energy produced by Reykjanes power plant.

The main benefits from deep geothermal drilling are as here below:

  • Increased power output per well, assumed by an order of magnitude, and production of higher-value, high-pressure, high-temperature steam.
  • Development of an environmentally benign, high-enthalpy energy source below currently producing geothermal fields.
  • Extended lifetime of the exploited geothermal reservoirs and power generation facilities.
  • Re-evaluation of the geothermal resource base.
  • Industrial, educational, and economic spin-off.
  • Knowledge of permeabilities within drillfields below 2 km depth.
  • Knowledge of heat transfer from magma to water.
  • Heat sweeping by injection of water into hot, deep wells.
  • Advances in research on ocean floor hydrothermal systems.

Summarized from the website iddp.is and nea.is