The Dec. 1 Crown petroleum and natural gas public offering highlighted the sale of several leases for 鈥渙il shale鈥� southwest of Hudson Bay, Sask. 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, 鈥淚t鈥檚 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鈥檚 where all the oil comes from. The oil shale rocks are immature, and they鈥檙e usually younger in age than oil-bearing formations.鈥�
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 鈥渞etort鈥� 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. 鈥淭hey are exposed in some of the river cuts in the Pasquia Hills,鈥� 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.聽
It is contiguous, for the most part. In Alberta, they are deep enough to form oil and gas 鈥淵ou can map it for the southern half of Saskatchewan, for sure,鈥� Yurkowski explained.聽
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.
Younger, here is a relative term. 鈥淲e鈥檙e looking at 85 to 95 million years old,鈥� she said.
Oil shale is not oilsands, either. 鈥淥il shales are rocks that have kerogen in it, so they鈥檙e organic-rich rocks. Oilsands are sandy rocks that has oil migrated into it,鈥� 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鈥檚 the same formation, but deeper at Lloydminster, where it is drilled as opposed to mined at the surface. 鈥淚t鈥檚 the same thing,鈥� she said.
Shale oil, such as what comes from the Bakken in North Dakota and southeast Saskatchewan, is oil produced from 鈥渢ight鈥� shale formations of rock. In the case of the Bakken, this is considered the 鈥渟ource rock,鈥� where that oil originated, but it is deep and hot enough in the North Dakota 鈥渒itchen鈥� to have 鈥渃ooked鈥� 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.
Utah example
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: 鈥淣ot to be confused with shale oil, which is oil produced via horizontal wells and hydraulic fracturing,聽oil shale聽must be heated to high temperatures to convert the organic matter (kerogen) into usable oil.
鈥淪hale 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 (5 per cent or more) of organic matter鈥攖he fossil remains of protozoans, microscopic animals, or plants鈥攃alled 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).
鈥淗owever, in Utah鈥檚 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 鈥渃ook鈥� the kerogen, thus speeding up the process from millions of years to days.鈥�
Not a lot of success has been had, as the same web page notes, 鈥淐urrently, only a few companies are pursuing oil shale development in Utah, all focusing on near surface deposits in the southeastern part of the resource.鈥� The web page鈥檚 most recent entries are over a decade old.
Yurkowski noted that oil shale has been produced in Estonia, China, Brazil, Scotland and Germany.
鈥淓stonia is the largest producer of it,鈥� she said.
As for oil shale around Hudson Bay, Yurkowski said, 鈥淲e've been aware of them for a long time and there's been 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,鈥� 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.聽
鈥淭he Government of Saskatchewan is pleased to see renewed interest in Saskatchewan鈥檚 extensive oil shale resources,鈥� Energy and Resources Acting Deputy Minister Doug MacKnight said. 鈥淒ecember鈥檚 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鈥檚 energy sector.鈥�
