Think "pipeline dispute" and the mind may conjure up images of environmental protest, pro-oil rallies and bickering politicians.
But there's another kind of dispute simmering over pipelines these days — one that could shake-up the sector for years to come and is dividing opinions in the Canadian oilpatch.
It may also offer an early test of the new Canada Energy Regulator (CER), which replaced the National Energy Board only a few weeks ago.
"This could be a market-altering event," said Jackie Forrest, senior director at the ARC Energy Research Institute.
"We have to tread very carefully in terms of understanding what the implications of this massive change will be for the industry and the markets."
At issue is a proposal by Calgary-based Enbridge to revamp its Mainline system, changing how it assigns space on the pipeline network responsible for most of Canada's oil transportation.
For decades, the Mainline has operated as a 100 per cent common carrier.
"Every month, anyone that wants to ship on the line can say that they want to ship and how much they want to ship and that space gets divvied up," Forest said. "It's open for everyone."
Enbridge's new proposal is to reduce the common-carrier portion of the Mainline to 10 per cent, while 90 per cent would be designated for companies signed up for longer contracts of up to 20 years.
The company says it's responding to what it's heard from its many stakeholders, including shippers, producers, refiners and marketers in both Canada and the United States.
"They want to be able access the same services from Enbridge that are currently available on competing pipelines," said Guy Jarvis, the company's executive vice president of liquids pipelines.
"Priority access, toll certainty and the potential to contract for terms of up to 20 years."
It's not a plan that sits well with everyone, though.
In August, Enbridge announced a two-month "open season," a period when it will accept bids from shippers who want to sign longer-term contracts for priority transport on the Mainline.
This spurred several companies to stake out their opposition, including Suncor, Shell Canada and MEG Energy, as well as the Explorers and Producers Association of Canada (EPAC).
Suncor, the country's largest oil and gas producer by market capitalization, wants the Canada Energy Regulator (CER) to put the brakes on the open-season process.
In its submission to the federal regulator, Suncor says the open season effectively compels shippers to bid for contracted space even if they consider the terms and conditions of service and tolls to be "unclear, uncertain, inappropriate, unfair or unjust and unreasonable."
It asks the regulator to declare that Enbridge cannot offer contract carriage, or require binding contracts be signed, until the terms and conditions of the new system, including tolls, receive regulatory approval.
EPAC, whose members represent about 20 per cent of Canadian oil and gas production, is concerned about the timing of the Enbridge proposal when some producers are already facing struggles getting oil to market.
"There is a severe shortage of pipeline capacity, a high level of apportionment, and no certainty as to future capacity additions," association president Tristan Goodman wrote in a submission to the CER.
"There are no other alternatives for the captured shippers. This puts our members in an untenable position of having to contract for firm service for fear of being blocked out of capacity, and not because it is in their best interest to do so."
Still, there are other businesses that support a revamp, including oilsands giant Cenovus Energy.
Cenovus told the regulator it believes the changes will provide certainty for shippers moving volumes of oil to downstream markets, which includes refineries.
It also agrees with Enbridge that the regulator should not interrupt the established open-season process, used to gauge whether there is shipper interest in the service.
"The harm that will arise from upending the established practice will be yet another indication to companies and investors that the regulatory process in Canada is uncertain and may be adjusted on an ad hoc basis," Cenovus wrote.
Enbridge fired back in its own submissions it would be "unjust and unreasonable" to be required to obtain regulatory approval of its proposed Mainline changes before it had the chance to gauge shipper interest in the service.
No other pipeline in Canada has been required to follow such a process, Enbridge says.
Opponents of the Enbridge proposal hope the CER will make the decision to pause the project in the coming days. But first the regulator's six-member commission may have to decide whether it has the jurisdiction to take such action.
With the open season set to end on Oct. 2, the clock is ticking. It's a decision the industry will be watching closely.