Wednesday, 30 September 2015

Gas sampling near hell...by Gemma Purser and Tom Barlow

Evening sunshine on Krafla
Preparing to journey into the heart of a volcano...........

This story begins in Iceland back in 2009 during the Iceland deep drilling project (IDDP). The project was established to explore for supercritical geothermal fluids in the area around the Krafla Volcano, Northern Iceland.

Geothermal energy is the ability to harness heat energy carried by hot geothermal fluids which circulate in zones around magma. Geothermal energy contributes to 27 % of Iceland’s total energy supply. Hotter fluids are produced the closer the borehole can be drilled towards this magma with supercritical geothermal borehole producing approx 10 times more energy than conventional wells.

It was intended that the IDDP-1 borehole (the first to be drilled in the project) would be drilled to a depth of 4.5 km, to access the fluids at temperatures of 400°C and above. However at just over 2 km the drill unexpectedly struck the magma chamber directly.

So what does all this have to do with two geochemists from the British Geological Survey?

Recently a project has been developing to re-drill, intentionally, back into the same magma chamber. This will help us to better understand the geochemistry, fluid flow and sealing mechanisms of these geothermal systems. This project, supported by the International continental drilling programme (ICDP) will see international collaboration from scientist undertaking work at Krafla close to the Landsvirkjun power station site. Landsvirkjun, is the national energy company of Iceland and were the hosts during our visit to Iceland.

Gases such as CO2, H2S and Radon are released from geothermal fluids as they circulate from deep underground to nearer the surface. By mapping the location and concentration of gases we can start to build up a picture of the subsurface.

Tom Barlow measuring gas concentration for carbon dioxide, hydrogen sulphide and radon 
For the past two weeks, Tom Barlow and I have been out doing exactly that. We worked with a team of scientists from the Italian national institute of geophysics and volcanology (INGV). We undertook soil gas measurements as part of a baseline survey around the Krafla caldera in an area around the IDDP-1 well and the Viti crater formed from an explosion in 1724. This work will help define the background conditions on the site before the drilling stage of the Krafla Magma Drilling Project (KMDP). The main aim was to complete 3 survey areas, each approx  1 km2 to locate the best position in which to install a permanent Radon monitoring station. Gas flux measurements were taken every 50 metres, gas concentrations every 100 metres and radon gas every 200 metres in a systematic grid pattern. This involved a lot of walking and negotiating the steep and rough terrain of a volcanic landscape. During our work we both spent time answering questions from inquisitive tourists and enjoyed taking the time out to explain more about BGS and the project.

The area over which the soil gas survey gas performed,
showing the steep terrain and gas explosion craters
Despite a couple of setbacks due to poor weather, a strong team effort between BGS and INGV resulted in the production of a final map showing CO2 gas flux, soil temperature and gas concentration maps for all the areas and a potential future site identified for the deployment of permanent radon monitoring equipment.  In addition we took fluids from the natural geothermal pools and drilled geothermal boreholes to get a better understanding of the fluid rock reactions occurring underneath the surface. Tom will now analyse the collected fluids in the BGS inorganic geochemistry facility as part of an inter-lab comparison with INGV in Italy.

Some of you may be interested to know that the word ‘viti’ in Icelandic means ‘hell’ . Given the horizontal rain, single figure temperatures and swarms of the local and infamous Myvatn lake midges at times the trip could have nearly felt like it. However, it was actually a great experience to work in such a stunning landscape and when the bad weather did subside we were treated to one of nature’s most spectacular shows. We were able to watch the northern lights dancing across the sky over the power station at Krafla, just magical!

Iceland was an awesome place in which to undertake fieldwork and it was great to be involved in an international collaboration and work with scientists from INGV at the very beginning of what will be a very novel, ambitious and exciting project of the future. Watch this space for future blog posts...........

The Northern Lilghts over Krafla

Thank you to Landsvirkjun for accommodating us at the site during the entire trip and to Sue Loughlin, BGS Edinburgh and Chris Rochelle, BGS Keyworth for the opportunity.

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