Canada was the world's fourth-largest producer of oil in 2018, according to the U.S. Energy Information Administration. What is more, Canada was also the fifth-largest producer of natural gas in 2017 (2018 numbers were not yet available). It is not surprising that energy firms dominate the ranks of the biggest Canadian energy companies. Each of the top seven companies had a market capitalization above $10 billion.

1. Enbridge Inc.

Enbridge Inc. (NYSE: ENB, TSX: ENB.TO) had a market capitalization of 74.62 billion U.S. dollars (98.06 billion Canadian) on November 1, 2019. Enbridge is the largest energy company in Canada, but it focuses on transporting rather than producing energy. Enbridge's businesses include oil pipelines, natural gas distribution, and alternative energy.

2. Suncor Energy Inc.

Suncor Energy Inc. (NYSE: SU, TSX: SU.TO) is an integrated oil and gas company with operations across Canada and in the United States. The company's Canadian oil sands properties deliver the lion's share of its annual production. In 2019, Suncor was Canada's second-largest energy company with a market capitalization of 47.65 billion U.S. dollars (63.29 billion Canadian).

3. TC Energy Corporation

TC Energy Corporation (NYSE: TRP, TSX: TRP.TO), which was formerly known as TransCanada, is an energy conglomerate with operations in energy infrastructure and power generation. Its extensive oil and natural gas pipeline operations stretch across Canada and the U.S. It had a market capitalization of 47.68 billion U.S. dollars (62.17 billion Canadian) as of November 2019.

4. Canadian Natural Resources

Canadian Natural Resources Ltd. (NYSE: CNQ, TSX: CNQ.TO) is an exploration and production company with crude oil and natural gas operations in Western Canada and crude oil operations in offshore African waters and the North Sea. In late 2019, Canadian Natural Resources had a market capitalization of 30.82 billion U.S. dollars (40.42 billion Canadian).

5. Imperial Oil

Imperial Oil Ltd. (TSX: IMO.TO) is an integrated oil and gas giant. In addition to refining and petrochemical operations, the company also markets fuel, lubricants, and other products under the Esso and Mobil brands. Imperial Oil has a market capitalization of about 19.20 billion U.S. dollars (25.23 billion Canadian)

6. Pembina Pipeline Corporation (PBA)

Pembina Pipeline Corporation (NYSE: PBA, TSX: PPL.TO) had a market capitalization of about 18.00 billion U.S. dollars (23.66 billion Canadian) on November 1, 2019. The company has three divisions focusing on pipelines, processing, and new ventures. Pembina began operations in 1997, and its headquarters in Calgary supports a focus on Western Canada.

7. Cenovus Energy

Cenovus Energy, Inc. (NYSE: CVE, TSX: CVE.TO) is another large integrated energy company with oil and gas exploration operations. The firm is also involved in oil production and refining. In addition to conventional oil and natural gas properties, the company has substantial oil sands holdings, which expanded when the Cenovus bought out the 50% stake of ConocoPhillips in 2017. The company had a market capitalization of 10.72 billion U.S. dollars (14.06 billion Canadian) as of November 2019.