Calgary-based energy pipeline firm Enbridge says it will spend about $1.2 billion to expand its network serving the oilsands in northern Alberta.

Enbridge will twin the 345-kilometre southern section of the Athabasca Pipeline, which runs from Kirby Lake to a crude oil processing hub in Hardisty in east-central Alberta, increasing capacity by about 450,000 barrels per day.

The expansion will create the potential to increase that to 800,000 barrels per day.

The firm said Monday it expects startup in early 2015, with full initial capacity available by 2016.

"Twinning our Athabasca system south of Kirby represents a highly efficient solution to the needs we are seeing for additional long-haul and short-haul capacity into Hardisty, leveraging off the advantages of our existing asset base and right-of-way," Enbridge president of liquids pipelines Stephen Wuori said in a statement.

New pipeline expandable

"While anchored by the needs of our current connected projects, it is readily expandable to accommodate new projects which are also expected to require pipeline capacity beginning mid-decade."

The existing pipeline has a maximum capacity of 570,000 barrels per day after being itself upgraded.

Canadian Natural Resources Ltd. is working on the first $1.25-billion phase of a new oilsands project at Kirby, near Lac La Biche, Alta.

In all, that project could have an ultimate capacity of between 70,000 and 100,000 barrels of oil per day.

The Canadian divisions of the BP PLC and Devon Corp. have a joint venture to develop land at Kirby as well.

Enbridge shares closed down 27 cents, or 0.85 per cent, at $31.58 on the Toronto Stock Exchange Monday.

With files from The Canadian Press