The Crown petroleum and natural gas public offering Dec. 1 highlighted the sale of several leases for “oil shale” southwest of Hudson Bay.
But what exactly is oil shale? Is it shale oil, like the Bakken? Is it oilsands like around Fort McMurray? Or is it something else?
Melinda Yurkowski is the assistant chief geologist of Saskatchewan, working with the Saskatchewan Geological Survey, part of the Ministry of Energy and Resources. She explained by phone from Regina on Dec. 4, “It’s the younger brother of the source rock that generates oil and gas. Essentially it is very rich in organic sedimentary material called kerogen. And this kerogen, if it gets buried deep enough and has enough pressure to it, it will thermally crack, and it will convert itself to oil, and that’s where all the oil comes from. The oil shale rocks are immature, and they’re usually younger in age than oil-bearing formations.”
In other words, the fluid within the rock has the prospect of becoming oil, and in natural processes, that could occur over the next tens of millions of years. But it is not oil yet. Where it has been developed around the world, oil shale is mined and then they “retort” it, which is heating to high-temperatures, to create a synthetic oil.
The oil shale rocks are exposed at some places on the surface near Hudson Bay. “They are exposed in some of the river cuts in the Pasquia Hills,” she said.
Under the surface, they run from the Manitoba Escarpment (of which Riding Mountain National Park is the most obvious example) to Alberta, as far north as the Peace River Arch and as far south as Texas.
It is contiguous, for the most part. In Alberta, they are deep enough to form oil and gas.
“You can map it for the southern half of Saskatchewan, for sure,” Yurkowski explained.
These rocks were laid down at the bottom of a giant inland sea that covered most of the interior plains of the United States and Canada.
They are part of the Colorado Group, with formations running from the First White Speckled Shale to the Fish Scales formations.
“We’re looking at 85 to 95 million years old,” she said.
Oil shale is not oilsands, either.
“Oil shales are rocks that have kerogen in it, so they’re organic-rich rocks. Oilsands are sandy rocks that has oil migrated into it,” she said.
Yurkowski pointed out the only difference between the oilsands around Fort McMurray and the heavy oil produced from the Mannville formation near Lloydminster is the depth. It’s the same formation, but deeper at Lloydminster, where it is drilled as opposed to mined at the surface. “It’s the same thing,” she said.
Shale oil, such as what comes from the Bakken in North Dakota and southeast Saskatchewan, is oil produced from “tight” shale formations of rock. In the case of the Bakken, this is considered the “source rock,” where that oil originated, but it is deep and hot enough in the North Dakota “kitchen” to have “cooked” those kerogens into oil. That depth is not present at Hudson Bay, where the oil shale is just below the glacial till, i.e. the layer of the earth closest to the surface that was recently disturbed by glacial ice sheets.
Yurkowski said there has been a lot of work over the decades trying to extract oil from oil shale in Utah.
The Utah Geological Survey website describes oil shale this way: “Not to be confused with shale oil, which is oil produced via horizontal wells and hydraulic fracturing, oil shale must be heated to high temperatures to convert the organic matter (kerogen) into usable oil.
“Shale is a fine-grained sedimentary rock composed of mud containing clays and silt-size particles of other minerals. Some shale can also contain significant amounts (five per cent or more) of organic matter — the fossil remains of protozoans, microscopic animals, or plants — called kerogen. When kerogen-bearing shale is buried deeply enough and for millions of years, the natural heat and pressure of the earth can convert the kerogen to oil (and/or gas).
“However, in Utah’s oil-shale deposits, much of the kerogen-bearing rock is close to the surface and therefore has not yet generated hydrocarbons. The oil industry has for years attempted to develop economic techniques to artificially “cook” the kerogen, thus speeding up the process from millions of years to days.”
Not a lot of success has been had, as the same web page notes: “Currently, only a few companies are pursuing oil shale development in Utah, all focusing on near surface deposits in the southeastern part of the resource.” The web page’s most recent entries are over a decade old.
Yurkowski noted that oil shale has been produced in Estonia, China, Brazil, Scotland and Germany.
“Estonia is the largest producer of it,” she said.
As for oil shale around Hudson Bay, Yurkowski said, “We've been aware of them for a long time and … a various sort of companies have gone in there and have taken a look at it. And in the past, technology's always been a bit of a challenge,” she said.
Interest in oil shales has historically often been linked to high prices of oil. The last time Yurkowski was asked about it was in 2012, when oil was around US$100 per barrel for West Texas Intermediate.
“The Government of Saskatchewan is pleased to see renewed interest in Saskatchewan’s extensive oil shale resources,” Energy and Resources Acting Deputy Minister Doug MacKnight said. “December’s public offering saw six accepted bids for oil shale leases in East Central Saskatchewan, the first oil shale leases ever to be issued through a public offering. This is definitely a step in the right direction when it comes to developing new and innovative projects for Saskatchewan’s energy sector.”