Russian scientists make calculations to improve Arctic energy resource extraction safety

MOSCOW, October 9. /TASS/. Russian mathematicians and geologists conducted a series of experiments and calculations, where they for the first time studied how unilateral warming of frozen rocks in the Arctic increases the risk of gas emissions that threaten infrastructures and personnel. Results of these experiments and calculations will help make resource extraction safer, press service of Skoltech (part of the VEB.RF group) said.

"We have shown how metastable methane hydrates behave in frozen rocks when heated," the press service quoted Skoltech's leading researcher Evgeny Chuvilin as saying. "Previously, many models considered only a decrease in pressure as the cause of hydrate decomposition. But in the Arctic, a well is heating the frozen rock, and the process develops somewhat differently. We can see that the pore hydrate begins to decompose at temperatures below zero, well before the frozen rock begins thawing."

Huge reserves of so-called methane hydrates or clathrates lay inside the marine and onshore permafrost deposits in the Russian and foreign Arctic, the scientist and his colleagues said. This is what scientists call water and methane compounds that remain stable at low temperatures, high pressures, or at a combination of both. Human activity and global warming are destabilizing them, leading to a sharp release of gas and to formation of giant funnels, domes and other peculiar structures.

The proximity of such deposits to oil and gas wells may destabilize methane hydrates, since these structures can heat the upper layer of frozen rocks during the natural resources' extraction. With this in mind, Russian scientists conducted a series of experiments with analogues of Arctic permafrost deposits containing methane hydrates, and used them to create a computer model of these deposits.

The conducted experiments and calculations have shown that with unilateral heating, the hydrates decomposition begins at minus 1.1 degrees Celsius, while the ice began to melt only at minus 0.01 degrees Celsius. In other words, with prolonged thermal exposure, hydrate decomposition outstrips ice melting, which must be taken into account when extracting natural resources in the Arctic.

"We can see that the pore hydrate begins to decompose at temperatures below zero, even before the frozen rock begins to melt," the scientist said in conclusion. "This changes the estimate of how quickly a gas release zone may form around the well. This means that the intra-permafrost hydrate decomposition zone is formed earlier than we have thought, and this must be taken into account when designing production wells so that not to receive an unexpected influx of annular gas or a soil subsidence area around the well."