Methane Threat: The Alarming Migration of Natural Gas Under Permafrost
According to scientists, large amounts of methane may be stored beneath the permafrost and could leak if it thaws.
Methane is spreading beneath the permafrost in Svalbard, according to research. While lowland areas contain ice-rich permafrost that acts as an excellent gas seal, highland areas with less ice appear more porous. If permafrost thaws excessively, greenhouse gas emissions could escape, increasing temperatures.
Millions of cubic meters of methane remain trapped underneath Svalbard’s permafrost, and scientists have discovered that it can travel beneath the frigid seal and escape. A large-scale escape might set off a warming cycle that would cause methane emissions to skyrocket: warmth thaws the permafrost, enabling more gas to run, leading more permafrost to thaw and more gas to be expelled. Because Svalbard’s geological and glacial history is so akin to the rest of the Arctic, these migratory methane deposits are expected to exist elsewhere in the Arctic.
Dr. Thomas Birchall, the lead author of the Frontiers in Earth Science study from the University Center in Svalbard, stated that methane is a potent greenhouse gas. He further noted that the leakage from below permafrost is minimal. Still, factors like glacial retreat and permafrost thawing might reveal increased emissions in the future.
Cold Storage
Svalbard has a lot of permafrost, which is ground that stays below zero degrees Celsius for two years or more. It is, however, not uniform or constant. Because ocean waters warm the west of Svalbard, permafrost is shallower and patchier. The highland permafrost is drier and more porous, whereas the lowland permafrost is more ice-saturated. The rocks beneath are frequently fossil fuel sources, releasing methane trapped by permafrost. Even in areas with continuous permafrost, certain geological features may enable gas to escape.
Because of its lack of access, the permafrost base is difficult to investigate. However, several wellbores have been drilled into the permafrost throughout the years by firms hunting for fossil fuels. Scientists applied historical information from commercial and research wellbores to plot the permafrost and locate permafrost gas buildups across Svalbard.
Birchall mentioned that he and his supervisor, Kim, had reviewed substantial historical wellbore data in Svalbard. He added that Kim had observed a recurring theme, specifically, the presence of gas accumulations at the base of the permafrost.
Discovering Methane Accumulations
Preliminary temperature assessments frequently encounter challenges due to the application of heated drilling mud to prevent wellbore freezing. Nevertheless, the extended examination of temperature trends and ongoing borehole monitoring facilitated the scientists in discerning the presence of permafrost. Additionally, their investigation encompassed detecting ice formation within the wellbore, alterations in drill cuttings generated during the drilling process, and variations in background gas measurements.
The wellbore monitors detected gas influxes, revealing accumulations beneath the permafrost and aberrant pressure measurements, indicating that the cold permafrost was functioning as a seal. In other situations, even when the permafrost and underlying geology favored gas retention and the rocks served as known hydrocarbon sources, explorations revealed no gas, suggesting that the generated gas had already migrated.
A Surprisingly Common Discover
Gas accumulations were significantly more common than expected, according to the experts. Eight of the 18 hydrocarbon exploration wells drilled in Svalbard revealed signs of permafrost, with half encountering gas accumulations.
Birchall noted that wells encountering gas accumulations did so coincidentally. In contrast, hydrocarbon exploration wells deliberately targeting accumulations in conventional settings had a success rate below 50%. He remarked on the prevalence of such incidents, citing an anecdotal example involving a recently drilled wellbore near the airport in Longyearbyen. Birchall explained that upon hearing a bubbling sound from the well, they decided to investigate, using rudimentary alarms designed for detecting explosive levels of methane, which were promptly triggered when held over the wellbore.
Climate Change Implications
According to experts, the active component of permafrost — the layer above one or two meters that thaws and freezes annually — is growing as the temperature warms. However, we understand less about how, if at all, the deeper permafrost is altering. Understanding this requires knowledge of the fluid flow beneath the permafrost. If permafrost becomes thinner and patchier, methane may find it easier to move and escape, speeding global warming and intensifying the climate crisis.
Read the original article on SciTechDaily.
Read more: The Urgent Need for Stringent Methane Emission Policies.
