High Quality Content by WIKIPEDIA articles! Petro-Canada was a crown corporation of Canada in the field of oil and natural gas. It was headquartered in the Petro-Canada Centre in Calgary, Alberta. In August, 2009, Petro-Canada merged with Suncor Energy, a deal in which Suncor investors received approximately 60 per cent ownership of the combined company and Petro-Canada investors received approximately 40 percent. The combined company retained the Suncor Energy name for upstream operations and uses the Petro-Canada brand nationwide for downstream retail operations.