Oil remains a dominant source of energy worldwide, fueled by giant oil corporations that feed billions of barrels daily of petroleum products to energy thirsty economies. All this despite rising public concerns about climate change and moves to reduce the use of carbon-based fuels such oil. To be sure, oil prices have suffered from extreme volatility in 2020 as a result of the COVID-19 pandemic and exacerbating trade tensions. But many of the world's leading oil companies still have generated significant revenue. We look below at the 10 biggest oil companies by 12-month trailing (TTM) revenue. While Chinese and U.S. companies make up half of the 10 companies, major players also are from Saudi Arabia, Europe and Russia. This list is limited to companies which are publicly traded in the U.S. or Canada, either directly or through ADRs. Some foreign companies may report semiannually, and so may have longer lag times. All data provided by YCharts and as of September 9, 2020.

#1 China Petroleum & Chemical Corp. (SNP)

China Petroleum & Chemical is a producer and distributor of a variety of petrochemical and petroleum products. The company's products include gasoline, diesel, kerosene, synthetic rubbers and resins, jet fuel, and chemical fertilizers, among other related offerings. Also known as Sinopec, China Petroleum & Chemical is among the very largest oil refining, gas, and petrochemical companies in the world.

#2 PetroChina Co. Ltd. (PTR)

Oil and gas company PetroChina is engaged in oil products exploration, development, production, and sales. The company's primary products include crude oil, petrochemical products, and their derivatives. PetroChina is the exchange-listed branch of the Chinese state-owned China National Petroleum Corporation and is counted among the largest oil and gas producers in business today.

#3 Saudi Arabian Oil. Co. (Saudi Aramco)

Saudi Aramco, which went public in 2019, is one of the largest companies in the world across all industries, as well as among the very largest global oil companies by revenue. This company is unusual in this list in that its stock does not trade in the U.S. While Investopedia would not normally include non-U.S.-listed stocks, Saudi Aramco is such a major player in the oil industry that a list of the biggest oil companies would not make sense without including it.

#4 Royal Dutch Shell PLC (RDS.A)

Based in the Netherlands, Royal Dutch Shell explores, produces, and refines petroleum through its subsidiary companies. In addition to operating gas stations around the world, Shell produces and sells fuels, lubricants, and other chemicals.

#5 BP PLC (BP)

British oil company BP is involved in oil and petrochemical exploration, production, and supply. The company refines and sells petroleum products including chemicals such as acetic acid, ethylene, polyethylene, and terephtalic acid. BP also generates solar energy for sale as well.

#6 Exxon Mobil Corp. (XOM)

Exxon Mobil is a global petroleum and petrochemicals business. The company explores, produces, trades, transports, and sells oil and natural gas. It's also involved in electrical power generation through coal and minerals operations. Among the many products that Exxon Mobil sells are fuel, lubricants, and other petroleum-derived chemicals. After Saudi Aramco, Exxon Mobil is the second-largest oil company in the world by market value even though Exxon Mobil is more than 10 times smaller than the Saudi Arabian company.

#7 Total SE (TOT)

Total, headquartered in France, explores and produces crude oil, natural gas, and low-carbon electricity. Total also refines and produces petrochemical products. The company owns and operates gas stations throughout Europe, the U.S., and Africa. Like most of its large competitors, Total is an integrated energy company that engages in all aspects of the oil and gas business, from exploration through sale.

#8 Chevron Corp. (CVX)

Chevron is an integrated oil company with primary business operations both upstream and downstream. The upstream division is involved in the exploration and production of oil and natural gas, while the downstream operations cover refining, transportation, and marketing. Chevron is also involved in chemical and mining operations as well as non-energy activities such as technology development.

#9 Marathon Petroleum Corp. (MPC)

Marathon is a crude oil refining company. Serving customers across the U.S., the company refines, supplies, transports, and sells petroleum products. Marathon is leaseholder or owner of thousands of miles of petroleum pipelines and has been the owner of the Speedway gas station chain. In early August, Marathon agreed to sell Speedway and its 4,000 outlets to Japan's Seven & i Holdings, for for $21 billion. The Japanese retailer is owner of 7 Eleven.

#10 PJSC Lukoil (LUKOY)

Russian oil and gas company Lukoil conducts exploration, production, refining, transportation, and marketing of petroleum products primarily in the Siberian region. The company distributes oil and petroleum through an extensive pipeline system and by ship, serving customers in both Russia and the U.S.