CALGARY — Canadian Natural Resources Ltd. (CNQ.TO) is considering adding a 30,000- to 40,000-barrel-per-day bitumen-only project to its Horizon oil sands mine to take advantage of excess ore production and pipeline capacity.

The proposed project could be approved as early as 2019 and would continue a trend in the sector to bolt on brownfield production to avoid the high costs and risks of building new mines from scratch.

The company has just completed its Phase 3 expansion to boost production at Horizon to 250,000 barrels per day of upgraded synthetic crude, a medium grade oil that sells for about the same price as New York benchmark West Texas Intermediate.

The new project would employ the same process used in Suncor Energy Inc.'s (SU.TO) nearly-completed Fort Hills mine project to produce a less valuable heavy oil that would not be upgraded and therefore would need to be diluted with light oil to flow in a pipeline to market.

Canadian Natural spokeswoman Julie Woo says the company has completed initial design work on the project.

She says it will now move to engineering and cost estimating before making a sanctioning decision.