MOSCOW, April 20. /TASS/. The Skolkovo Institute of Science and Technology (Skoltech) made a model to forecast heat impacts from oil and gas wells on the Arctic perennial frozen ground. The understanding of these processes is top important for safe work of the wells and for estimating greenhouse gas emissions, the institute’s press service said on Tuesday.
A precise thawing forecast is necessary to prevent soil subsidence, which, in turn, causes risks of wells’ flooding and stability disruptions, the institute’s scientists say. As for methane emissions, this aspect is important for two reasons. First of all, the gas may cause fire and destruction of the producing well. Secondly, methane is a strong greenhouse gas, and its emissions into the atmosphere must be taken into account to understand global and regional climate changes.
"We have modeled thawing processes around a well. In our work, we have analyzed specific operating conditions of a well on the Yamal Peninsula. However, similar processes may occur in other territories and around other types of wells, since apparently hydrocarbons rising from the depths are bringing the heat upwards: every 100 meters of depth is about another three degrees. In the deepest drilling, the oil temperature may reach 100 degrees Celsius or higher," the press service quoted the institute’s leading researcher Evgeny Chuvilin as saying.
Oil and natural gas deposits in the Arctic zone lie under the permafrost, which is 100 to 500 meters thick. All the production wells are drilled there through this perennially frozen layer. Since hydrocarbons have a relatively high temperature, when lifted they heat up the surrounding permafrost. The adjacent soil thaws and becomes less hard, which can affect the structure stability. Moreover, if the soil is saturated with methane, which is typical for West Siberia’s northern part, and in particular the Yamal Peninsula, the thawing ground produces releases of this fire-hazardous and climate-damaging gas.
Skoltech’s scientists have been working with partners from the Sergeyev Institute of Geoecology (the Russian Academy of Sciences) with the support from the Total Energies Company. The model, they have made, demonstrates how working wells heat gradually the ground around them, causing the permafrost’s melting. However, this is not the only result of this work.
"Complex" permafrost
"We’ve eyed the case of a more complex variant of the permafrost, which at the depth of 60-120 meters contains gas hydrates - these are ice-like compounds of gas and water, which are stable within a certain range of temperatures and pressures. When decomposed, they emit about 170 volumes of free gas per one volume of gas hydrate. We have demonstrated that a 30-years’ operation of one gas well may form a thawing area with a radius of 10 meters or more, and simultaneously it may emit into the atmosphere up to 500,000 cubic meters of methane," the expert added.