Troublemaker Methane: New Apparatus To Simulate Arctic Explosions

Russian researchers have developed an experimental setup that will help simulate gas-dynamic processes and predict explosions in Arctic soils. Over the past decade, global warming has caused permafrost to thaw, leading to more frequent explosions of subglacial methane. It is vital to prevent these events, which pose a major threat to gas pipelines, wells, and the like. Experts claim it is impossible to predict a gas explosion, but there are ways to make some facilities safer through monitoring, and also to anticipate the intensity of emissions in certain areas.

Gas emission model

Skoltech researchers have built and successfully tested an experimental setup, unique in Russia, that can simulate gas dynamics in frozen soil and estimate the likelihood of methane explosions. Global warming has led to more frequent and powerful explosions of gas accumulated in the Arctic’s frozen ground, posing a risk to gas pipelines, production wells, and other engineering facilities, as well as to local populations and livestock. In addition, the simulation will help assess the impact of these explosive emissions on the climate: Methane is 28 times more efficient than CO2 at trapping heat in the atmosphere.

Rock permeability — a key parameter for understanding and predicting methane eruptions — indicates whether and how easily gas can seep through the ground. Permafrost is usually taken to be impervious to gas up until the point when it thaws, whereupon its permeability is determined by soil composition and calculated for fixed conditions defined by industry standards.

This simplified approach, however, does not allow gas eruptions to be predicted accurately, because it ignores a variety of changing and interrelated natural factors such as temperature, pressure, and soil saturation with unfrozen water and hydrates. This has led the scientists to propose a new approach.

“Until recently, Russia lacked the experimental facilities for studying the behavior of several parameters of ice hydrates at once. Most of the solutions used in other countries also operate under fixed conditions. We proposed to study a wider range of conditions and parameter behaviors to better reflect reality. Now we can simulate interesting natural scenarios and test various theoretical propositions, getting closer to predicting methane eruptions from permafrost,” says Maxim Zhmaev, an engineer at Skoltech Petroleum and a PhD student in Skoltech’s Petroleum Engineering program.

In the Arctic, natural gas slowly accumulates in the upper horizons of the permafrost, both on land and underwater, forming huge deposits. When the pressure reaches critical levels, the gas erupts from the frozen rock to the surface. On land, the explosions are often accompanied by fires. Large debris is thrown tens of meters into the air and a huge crater is formed. Over time, it fills with water and resembles a natural lake, experts say.

Skotlech’s new apparatus is designed to perform experiments on frozen rock samples and to simulate a wide range of natural conditions by varying the ambient temperature and gas pressure according to a specified pattern. The unique sample holder helps to compact the soil during the experiment and to measure changes in its linear dimensions and therefore porosity. The facility is equipped with acoustic sensors to detect changes in the ratio of ice, unfrozen water, and other phase components. In this way, it is possible not only to measure gas permeability, but also to begin to study the complex processes that occur in real soil.

“Our trial experiments using this new test unit have shown that the proposed approach works. For example, we were able to measure the critical temperatures at which the frozen but somewhat heated rock becomes partially permeable. We also investigated the range of pressures that are quite high, but not high enough to cause the formation of gas hydrates. This is a big step forward from determining soil properties to a more detailed and realistic simulation of natural processes, such as gas eruptions from the permafrost,” says Evgeny Chuvilin, the study’s principal investigator and a leading research scientist at Skoltech’s Petroleum Center.

Predicting gas explosions in the North

According to Vasily Bogoyavlensky, the deputy director for science at the Institute of Oil and Gas Problems of RAS, explosions in the Arctic will continue, but their timing and location cannot be predicted with certainty. As with earthquakes and volcanic eruptions, predictions can only be made through continuous monitoring of individual formations, based on the changes in their behavior detected by instruments. And even then, this would only be a prediction of a fairly long-term probability of an event.

“We have been studying explosions in the Arctic for 10 years and know almost everything about them. The rapid growth of a mound is the key indicator of an impending eruption. Of the two mounds we studied this year one exploded on August 30. Its growth rate was unusually high, more than 50 centimeters per year. Mounds can be monitored from space. We are currently looking at potentially dangerous spots in the Bovanenkovskoye field in Yamal,” Bogoyavlensky said.

Nevertheless, he added that the simulation using the new apparatus will be useful for understanding how and at what temperature various soils start to leak gas.

The coordinator of the industrial greening program of the Biodiversity Conservation Center Igor Shkradyuk said that while individual explosive events cannot be predicted, the increase in their intensity can be.

“Methane, which is produced by the fermentation of biomass, has a close cousin, the marsh gas, which sometimes bubbles up and catches fire. Trapped in the permafrost, methane has accumulated underground for tens of thousands of years. As the permafrost thaws, the gas escapes,” said Shkraduyk, who also serves as an expert at the International Socio-Ecological Union.

There are six billion tons of methane underground, hundreds of times more than in the atmosphere. As the ice thaws, emissions occur much more often than a decade ago, and the trend will continue. There are about 2,000 seeps at the bottom of the Arctic Ocean, and many more on polar islands. Their explosions can be compared to the detonation of a 10-ton TNT bomb, Shkradyuk added.

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This story by Denis Gritsenko was originally published in Russian by Izvestia. The crater photos have been added courtesy of Leading Research Scientist Evgeny Chuvilin of Skoltech Petroleum.

The study reported in this story came out in the journal Cold Regions Science and Technology and was supported by Russian Science Foundation grant Nos. 22-17-00112 and 22-67-00025.

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