As the world's third-largest oil producer and second-largest natural gas producer, Russia is home to some of the biggest integrated oil and gas companies in the world. In fact, Russia's biggest companies by oil production volume include several mainstays on lists of the world's biggest companies.

All of Russia's largest oil companies maintain substantial upstream and downstream oil and gas operations, including sprawling exploration and production divisions, petroleum refineries and petrochemical plants, and retail service stations. The top five oil companies are ranked here according to oil production volume in 2014, the most recent year for which figures are available.

1. Rosneft

Rosneft is Russia's biggest oil company, with reported production of about 1.5 billion barrels in 2014. The company also ranks as Russia's third biggest natural gas company, with production amounting to more than 345 million barrel of oil equivalents (BOE). Rosneft has a market capitalization of nearly $38.7 billion, making it the highest publicly valued company in this list.

Rosneft maintains exploration and production activities across Russia and in 10 other countries, including the United States, Canada, Brazil, Norway and Vietnam. It operates 13 refineries in Russia and has an interest in seven additional refineries in Western and Eastern Europe. Rosneft also operates a network of over 2,400 retail gasoline service stations and is Russia's largest supplier of jet fuel.

2. Lukoil

Lukoil produced nearly 707 million barrels of oil in 2014 and ranked as the second-biggest producer in the country. The company's natural gas production came in at more than 92 million BOE on the year. It has a market capitalization of more than $27.7 billion.

In addition to gas and oil exploration and production activities across Russia, Lukoil operates in 12 other countries in Europe, Africa and the Middle East. Its refining and petrochemical operations include six refineries in Russia and an interest in five more refineries in New Zealand and Europe. Lukoil also operates power generation facilities in Russia and gasoline service stations in Russia, Europe and the U.S.

3. Gazprom Neft

Gazprom Neft is a subsidiary of the Russian energy giant Gazprom. Although Gazprom Neft has an independent listing on the Moscow Exchange, its parent holds more than 95% of its outstanding shares. The Russian government, in turn, holds 50% of Gazprom shares.

Gazprom Neft produced about 482 million barrels of oil in 2014. Natural gas production amounted to about 104 million BOE during the year. The company has production operations in Russia, Iraq, Venezuela and several other countries. It operates four refineries in Russia and another in Belarus. Nearly 1,750 Gazprom Neft service stations operate in Russia and Europe. Gazprom Neft has a market capitalization of nearly $10.5 billion.

4. Surgutneftegas

Surgutneftegas falls just behind Gazprom Neft with crude oil production of nearly 447 million barrels in 2014. Gas production rose to about 55.3 million BOE on the year. The company's operations are mostly confined to the domestic market. In addition to its exploration and production activities, the company operates a refinery and a gas processing plant, produces petrochemicals, and runs a power generation business. Surgutneftegas also operates nearly 300 service stations. It has a market capitalization of over $18.5 billion.

5. Tatneft

Tatneft produced almost 193 million barrels of oil in 2014, in addition to gas production of almost 5.5 million BOE. The company produces oil and gas primarily within Russia, although international projects are in development. Tatneft operates a refining and petrochemical complex, a second refining facility and a gas processing plant. A tire manufacturing facility is housed in the refining and petrochemical complex, where a total of 12.5 million tires were produced in 2013. Tatneft distributes refined petroleum products through its network of more than 650 service stations in Russia, Ukraine and Belarus. The company has a market capitalization of more than $9.7 billion.