Storage Time: Nova Scotia Holds Offshore CCUS Opportunities


Editor's note: This is the second of three articles exploring energy development potential in Nova Scotia. 

The first article is here: Opportunities Galore: Recent Call For Bids Offer Lots Of Potential For Nova Scotia Offshore

While Nova Scotia offshore carbon capture, utilization and storage (CCUS) development is still in its early stages, recent mapping, past production and the drilling history lends itself to a greater opportunity of understanding the potential, says Adam MacDonald, director of Subsurface Energy Development in the Department of Natural Resources and Renewables.

“This put offshore Nova Scotia ahead of the pack for CCS offshore in identifying the capability and capacity for CCS in offshore Nova Scotia,” he told the Bulletin. According to MacDonald, CCUS for offshore Nova Scotia likely would occur in the deep saline aquifers of the Cretaceous formations of the Scotian Shelf inland of the Sable Island bank and in and around any depleted oil and gas fields.

“It seems like industry is kind of knocking at our door, just because our current knowledge of CCS opportunities or possibilities in offshore Nova Scotia is huge. Some of the work that’s been done and some of the work we’re doing in house shows you could have potential to store as much CO2 as the country emits to date and store it offshore Nova Scotia.”

Grant Wach, professor in the Department of Earth and Environmental Sciences, Dalhousie University, said that while the life of an oil and gas field is perhaps 20-30 years, when used for storing CO2 the timeframe of its usefulness grows to more than a millennium. In fact, he told the DOB, the best places for CCS are proven or potential petroleum reservoirs, as are saline aquifers. Wach added that offshore Nova Scotia presents a huge opportunity for storing CO2.

“We have some great opportunities offshore, and we’re as close as one can get for the boundaries. Also, don’t forget, if you look at a geologic map, then there really are not any decent sedimentary basins between Boston and throughout up to Maine. And so, the U.S. is going to need some areas to sequester its CO2.

“There already is existing pipeline infrastructure between New England and Nova Scotia. And so, that could be integrated into an energy corridor and used for bringing CO2 up and sequestering it.”

Future for CCUS

In five years, Wach said, ideally he would like to see development of CO2 sequestration offshore Nova Scotia via pipelines bringing CO2 from Central Canada. Further, he would like to see development comingled with projects that start to extract hydrocarbons that can be incorporated from the offshore, with infrastructure developed to facilitate a boon for the East Coast economy in Canada.

“Also, I’d love to start to see the import of CO2 from the U.S. One thing we must look at and determine is: Who will get the carbon credits for that? Who will be assuming the liability? These are things that the federal government and provincial governments must sort out, looking at those opportunities we have.”

According to MacDonald, Nova Scotia’s CCUS is still in its early stages. What the province is doing, he noted, and what really must happen, is a legislation update — a regulation regime must be instituted for CCUS to flourish. “These things do not happen fast in government, of course. And it is competing with oil and gas, offshore wind. And then, of course, Nova Scotia is not a huge carbon producer. And so, it’s all largely dependent on transportation.”

He added: “We’ve done a lot of mapping. There is a lot of production and drilling history. And so, we are already well ahead of the game. We hope to do plume modelling as our next step to hit home why CCUS is a good opportunity for the offshore. Also, shipping carbon across the ocean is in play. There are a whole pile of rules and regulations that have to be sorted out before we can jump on that.”

Indeed, Canada must still develop the regulatory framework for licensing pore volume and also for injecting CO2 into the subsurface, Wach told the DOB. Fortunately, he said, while that must be sorted out, the federal government and provincial governments are working to finish that.

“At Weyburn, [companies] were transporting CO2 from the U.S. and sequestering that for secondary recovery purposes in Saskatchewan. And so, the regulatory framework exists for transporting the CO2 across international boundaries, but you still need the regulatory framework in place for transporting CO2 across provincial boundaries.”

Environment matters

On the environmental front, said Wach, containing carbon emissions is essential for tackling ocean acidification. In fact, the Dalhousie professor is leading a study into this very issue. “And so, we have to make sure we mitigate further acidification of the oceans and damage to fisheries by looking at that too.”

In terms of storing the CO2 in offshore reservoirs, he said, ensuring there is proper leak mitigation protocols are in place is essential — measures that would be basically the same as for mitigating offshore oil and gas leaks. “You have petroleum systems. You have a trap, a seal, a caprock, a reservoir. You want to mitigate migration pathways that might mitigate through a fault or fracture systems.

“You’re not really concerned about source rock. But, of course, source rock if it’s generating higher condensates, it needs to be assessed. You have to look at the diagenesis too. Because if you’re injecting CO2 in the liquid phase, then what impact might that have on the subsurface reservoirs? But these are problems, technology problems, that have been addressed before and can be addressed.”

He added: “These are huge volumes we have to sequester, and so we have to get started now so that in five years we’d like to see some progress in really trying to solve these problems of carbon capture.”

Further, Wach noted, there are geo-storage opportunities with offshore Nova Scotia, which involve not only the storage of CO2 but also energy from renewables — an opportunity to modernize infrastructure in the province. “The best way to look at that is compressed energy storage — compressed air storage — so in the off-peak times you can take the renewable energy and store it in the ground and turn it back up to turn the turbines during off-peak times.”

Geothermal potential

Meanwhile, Wach said, there exists potentially low-enthalpy geothermal offshore Nova Scotia. “Heat can only be transported a few kilometres, but power generation from low-enthalpy generators is being developed all the time. We’re going to start seeing [lower entry] requirements for geothermal, where turbines [costs] start to decrease.”

He added: “What we need to do is keep drilling and stepping out further offshore [to find] opportunities and also missed opportunities, and also the opportunities from CCS, and also geothermal.”

As wells go deeper, they get hotter, noted MacDonald, and some of the current wells offshore Nova Scotia can be upwards of six kilometres deep. There are more than 200 wells offshore Nova Scotia, each one of which carries warm temperatures. However, said MacDonald, while the province understands the geothermal energy is at depth due to the well drilling, it is not actively looking at geothermal offshore.

“The challenge, of course, is, first of all, operating underwater, and secondly, transporting that energy to shore. Everything, of course, is more complicated underwater, times 100. We are working on geothermal onshore. We are quite far along. We just gave a presentation at Geothermal Canada about Nova Scotia’s onshore geothermal.”


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