Geologists have discovered how the production of shale oil and gas makes the ground water radioactive

SL, Среда 19 Сентябрь 2018 - 17:29:51

The researchers described the process of water entering the radioactive isotopes that accompanies the extraction of shale oil and gas. The findings of scientists are described in two research articles published in the journal Chemical Geology group headed by Joshua Landis (Joshua Landis) from Dartmouth College in the United States.

Recall that the extraction of shale oil and gas is booming in recent years. With this technology, the United States already became a net exporter of natural gas in the coming years expect to achieve the same status with respect to oil. Despite the fact that the state with the first in the world by GDP and third largest by population consumes a lot of fossil fuels.

In General terms the process looks like. To well powerful pumps pumped the mixture of water, sand and chemical reagents. When the fluid pressure becomes too large, the geological formation is broken and crushed. Figuratively speaking, the fuel is dripping from deformed rocks, like water from a compressed sponge.

However, this technology carries ecological risk. The reagents used to partially enter the water and can cause health problems. In addition, "exhaust" water is enriched radioactive element radium.

Where does it come from? This was found out by the researchers in the first work. They put samples of shale in water enriched with salts of calcium. Explain what pumped underground fluid traveling through the numerous cracks inevitably absorbs these substances.

The researchers found that this solution and remove the radium from the surrounding shale. Thus there are two sources of threat elements, and they have a different ratio of the concentrations of radium-226 and radium-228. The first isotope is relatively stable: its half-life is more than a thousand years. The second is very active: for him, the same period is less than six years. The decay of radium emitted radiation, and singled out another radioactive element – radon.

The first source of the dangerous metal was inorganic mineral part of oil shale. In it one atom of radium-228 accounted for only 250 of atoms of radium-226. This is a fairly large concentration for the first isotope. The second source is the organic part of the breed. It is the ratio of radium-228 and radium-226 is 1 in 10000.

As shown by experiments, just a few hours, passes into solution and more than 14% contained in the shale is a radioactive element. For comparison, pure (not enriched with calcium salts) water washes away only less than 0.5%.

The second article describes the model of this transfer for different concentrations of salts in solution and different amounts of water, washing the slate. Here, the authors used an experiment, mathematical modelling and direct measurement of the amount of radium in the groundwater on-site extraction of shale hydrocarbons.

Prior to these studies, experts were not sure that the source of the radioactive metal are slates. There was a hypothesis that the case in natural accumulations of radium in the groundwater that sometimes occur.

"Interaction between water and rock occurring in kilometers from the surface very difficult to study, says Landis. – Our dimension [concentration] of radium isotopes give a new understanding of the problem".

Recall that "Conduct.Science" (nauka.vesti.ru) previously wrote about the unexpected source of radioactivity generated by the accident at NPP in Fukushima.




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