Getting a good look at gas hydrates
Getting a good look at gas hydrates
Vast stores of natural gas sit locked, frozen within a matrix of water molecules, in undersea sediments. Jeffrey Priest and his team at the University of Calgary aim to learn what would happen if large amounts of this resource, known as gas hydrates, were released from its icy storage — intentionally, as part of the search for new energy sources, or as an unwelcome result of climate change.
Using newly developed equipment funded by the Canada Foundation for Innovation’s (CFI) John R. Evans Leaders Fund, they’ll investigate whether the sediments might, in either situation, be weakened and destabilized enough to spawn subsea landslides and, in turn, unleash devastating tsunamis as the hydrates revert to water and methane gas.
The CFI’s support “will put us right at the top of the game in terms of being able to understand what’s going on,” says Priest, 49, Canada Research Chair in Geomechanics of Gas Hydrates, who came to Calgary from Britain two years ago to pursue his groundbreaking research.
Gas hydrates are a combination of methane gas and water that, under high pressure and low temperature, create an ice-like structure in marine deposits, which helps to strengthen the sediments. When temperatures rise or the pressure drops, the ice structure melts and the gas hydrate dissociates, reverting back to its components, methane gas and water.
They’ve been known about for centuries, but only as a curiosity, Priest says. It’s estimated that about 1,000 times more methane is trapped in hydrates than is consumed annually worldwide. Recent technology has opened the door to exploiting them, but impacts on sediment stability must be understood first.
Marine landslides can occur even on seafloors with slopes as shallow as one degree, Priest says. “Some of these failures are huge. The question is, ‘what’s doing this?’ ”
Researchers have tried to collect cores of hydrate-laden sediments for analysis, but their equipment couldn’t sustain the pressure required to keep the hydrates in place and the samples would “blow up,” Priest says. As a result, researchers have had to build artificial structures that only loosely approximated undersea conditions.
The new equipment can deliver cores intact to laboratories for real-world analysis. Priest, working at the University of Southampton, developed it between 2009 and 2012 in collaboration with Geotek, a British company specializing in analysis of geological cores.
A prototype of the new gear has been used in coastal waters off China and Japan. The CFI’s funding will support construction of the first full version, with improvements inspired by the prototype trials.
Priest’s research, which will include periods onboard a ship extracting sample cores, will help those seeking new energy supplies to determine whether certain gas hydrate reserves can be safely exploited.
For those dealing with climate-change, it could reveal potential landslide threats if the oceans, particularly in the Arctic, warm enough to melt the gas hydrates. Those findings, in turn, could improve our understanding of the need for tougher measures to reduce greenhouse-gas emissions or, more likely, regulations to reduce potential damage to people along vulnerable coastlines.
“If we know how to quantify the risk, from a regulatory point of view we can say we won’t allow development in certain areas or maybe even move people,” Priest says. “If you can quantify the end point, you can prepare society for it.”
It might seem strange for Priest to work on a marine issue in Calgary, far from any coast, but he says, “You don’t need to be next to the ocean.” Canada has large gas-hydrate reserves, Calgary is at the centre of the country’s oil and gas industry, and the university has a history of petroleum-related research, he notes.
Peter Gorrie is a Toronto-based freelance writer specializing in environment issues.