A new approach to gas exploration has uncovered a huge helium gas field in Tanzania, a discovery that could address the increasingly critical shortage of this vital yet rare element. A research group from Oxford and Durham universities developed the approach, together with Helium One, a Norway-headquartered helium exploration company.
Helium is essential for many modern technologies such as MRI scanners, nuclear energy, welding and industrial leak detection. And it is also used in many research facilities such as the Large Hadron Collider at CERN. Recent years have seen worries about the over-exploitation of this extremely limited, finite, valuable natural resource, with fears that supply could not be guaranteed into the medium to long-term future.
The lightness of helium means that it can escape off into space, to be lost forever, so a steady supply is needed. Known helium reserves are running out and until now the gas has never been found intentionally, only accidentally discovered in small quantities during oil and gas drilling.
The research team in Tanzania discovered that volcanic activity provides the intense heat necessary to release the gas from ancient, helium-bearing rocks. Within the Tanzanian East African Rift Valley, volcanoes have released helium from ancient deep rocks and have trapped this helium in shallower gas fields. Diveena Danabalan, a PhD student at Durham, presented the research at the Goldschmidt geochemistry conference in Yokohama, Japan.
‘We show that volcanoes in the Rift play an important role in the formation of viable helium reserves,” she says. “Volcanic activity likely provides the heat necessary to release the helium accumulated in ancient crustal rocks. However, if gas traps are located too close to a given volcano, they run the risk of helium being heavily diluted by volcanic gases such as carbon dioxide, just as we see in thermal springs from the region. We are now working to identify the ‘goldilocks-zone’ between the ancient crust and the modern volcanoes where the balance between helium release and volcanic dilution is just right.”
The research group had previously used mass spectroscopy to measure the amount of noble gases present in North American natural gas fields, speculating at the time that reservoirs of helium “almost certainly” exist in the Rocky Mountains.
“Now we understand the techniques, we anticipate more large helium finds”, says Chris Ballentine, a professor at Oxford, regarding the Tanzanian discovery. “This will help safeguard society’s future helium needs. By combining our understanding of helium geochemistry with seismic images of gas trapping structures, independent experts have calculated a probable resource of 54 billion cubic feet in just one part of the rift valley. This is around the size of 600,000 olympic sized swimming pools with helium gas. That’s nearly seven times the total amount of helium consumed globally every year and enough to fill over 1.2 million medical MRI scanners when converted to liquid helium.”
The group, according to Oxford’s Pete Barry, can now apply the same strategy to other parts of the world with similar geological history. “Excitingly, we have linked the importance of volcanic activity for helium release with the presence of potential trapping structures and this study represents another step towards creating a viable model for helium exploration. This is badly needed given the current demand for helium.”