Canadian regulators released a major report blaming four uncontrollable leaks in the heart of Alberta’s tar sands patch on an energy company’s injection of too much steam underground, while seeking to tap ever-deeper reserves.

Canadian Natural Resources Limited (CNRL) pushed the limit of how much steam it could reasonably inject underground at high pressures to release bitumen deep below the surface, concluded officials at Alberta Energy Regulator (AER). The report, published last month, also noted the area’s complex local geology as a critical contributing role. For one leak, officials partly blamed well-related failures. The combination of factors caused some of the crude to bubble up to the surface by way of natural or man-made cracks or faults in the bedrock, instead of through wells.

The report highlights the risks associated with the extraction method used to release deeply buried oil sands, called high-pressure cyclic steam stimulation (HPCSS). Perhaps more significantly, the government findings also expose possible geological risks, or geohazards, across the Alberta oil sands region.

Some geologists have warned that these geohazards could also compromise the most prevalent method for extracting reserves that are moderately deep, called steam assisted gravity drainage (SAGD). About 80 percent of the remaining oil sands reserves are locked deeper underground; the main methods to tap them are either HPCSS or SAGD.

“It’s concerning that things like this are coming to light long after the company has gone through its regulatory approval process,” Chris Severson-Baker, director of the Pembina Institute, told InsideClimate News. Pembina is a nonprofit dedicated to sustainability.

This AER investigation highlights how “there may be other really critical things that aren’t known about how these technologies can be safely applied,” he added.

CNRL discovered the four mysterious leaks between May and June 2013. The final leak, far from the others, was the most damaging. At that site, thick crude oozed into a small watering hole nearby and the result was deadly for wildlife: at least two beavers, 37 birds, 87 frogs and 22 small mammals were killed, coated in black goop. Dozens more animals were rescued and cleaned, and the company had to partly drain the pond.

One of the leak sites is undergoing remediation; the other three are cleaned up, according to CNRL. Still, some bitumen continues to seep out at levels “too small to measure,” according to company spokesperson Julie Woo. In all, the incidents have released more than 6,600 barrels of bitumen.

CNRL’s investigation had blamed the events largely on well-related failures. The company report, published in 2014, does acknowledge the possibility of other contributing factors, including its extraction process and local geology.

Regulators firmly disagreed, almost entirely blaming the company’s extraction process and other geological factors, including the presence of natural fractures, cracks or connections between bedrock layers above the oil sands. Also at work below some of the oil sands deposits is a slow process called salt dissolution, in which salt water flows into the rock and erodes it, creating fractures and holes. Consequently, all the pressure in the oil sands reservoir was likely causing the oil to flow up to the surface through the company well—as well as any other routes it encountered along the way to the surface.  

In an email, CNRL’s Woo wrote that the new government report “appears consistent” with the company’s own conclusions, which identify several possible causes for the leaks.

Officials at Alberta Energy Regulator took about three years to conduct their investigation of the leaks at CNRL’s Primrose facility. Their report does not actually say the extraction method CNRL used is inherently dangerous. Instead, officials cite the company’s misuse of the method—specifically, the injection of “excessive steam volumes” at high pressures. Still, regulators say in the report that much remains unknown about how all the bitumen traveled through the different rock layers to the surface, raising broader safety questions.

“What is clear is that the project itself had a design flaw and that excessive pressure at [the Primrose] location resulted in a blowout,” Pembina’s Severson-Baker told InsideClimate News.

This isn’t the first time Alberta regulators have flagged CNRL’s operations for pushing the boundaries of safety at this location. Back in 2009, the company discovered a similar mysterious surface leak of bitumen at its Primrose facility, near wells where it was injecting steam at especially high pressures. CNRL blamed the incident on a well-related failure; regulators raised concerns about the company’s extraction process and the local geology.

After the 2009 incident, regulators established new limits for CNRL relating to steam injection volumes. According to Woo, “there is a very small amount (too small to measure) of bitumen” being contained and collected there now.

Regulators are going even farther this time around, issuing a suite of rules for the Primrose facility. Some of the new controls, detailed in the report, include directing the company not to use the oil extraction process involving high pressure steam injection within 1,000 meters (nearly 3,300 feet) of the past leaks; to use less steam at lower pressures for extraction; and to conduct additional environmental monitoring.

According to CNRL’s Woo, the company is already looking to address the new requirements. The new controls at the Primrose and Wolf Lake site will continue to eat into the company’s production and the bottom line, which have both suffered since the leaks were identified. CNRL declined to comment on its projected financial losses.

“The response of the AER is a correct one,” said Maurice Dusseault, a professor of engineering geology at the University of Waterloo. “By placing limits on pressures and injection amounts, and by emphasizing the importance of surveillance, their actions are reducing the probability of future bitumen leakage events.”

CNRL’s Primrose facility is one of six in Alberta that uses high-pressure cyclic steam stimulation; three additional projects are in various stages of development, all run by different companies.

Andrew MacPherson, a director at AER, told InsideClimate News that regulators are looking into whether these facilities, and ones planned for the future, are in areas with geology that warrants further evaluation. In a later email, AER spokeswoman Monica Hermary wrote: “All new projects would also be subject to the requirements implemented” in this new ruling.

The regulator’s ruling will require other oil sands companies to take note, said Benjamin Cowie, a geology instructor at the University of Calgary and research associate at Harvard University.

Cowie is among a group of geologists who think geohazards could affect other types of facilities too, including those using steam assisted gravity drainage, or SAGD, to target shallower oil sands reserves.

Regulators are more skeptical, saying it’s unlikely the geological issues in play at Primrose would impact the shallower operations. There are around 20 active SAGD operations and about 40 more in various stages of approval.

When asked how the report’s findings could apply to the larger Alberta oil sands, the industry trade group Canadian Association of Petroleum Producers did not respond.