Both the Forbes Global 2000 and Petroleum Intelligence Weekly 50 do not include either KazMunaiGas or Gazprom Neft in their rankings of the world's largest firms. In future years, as the financial and journalistic community gains knowlendge of these firms, based on the size of these firms reserves and expected production of oil and natural gas, both KazMunaiGas and Gazprom Neft should place in the Forbes and PIW rankings.
Energy firms are very well represented among the largest public firms in the world, according to the Forbes Global 2000, which can be found here: http://en.wikipedia.org/wiki/Forbes_Global_2000#2008_list The Forbes Global 2000 ranks firms in terms of size according to a formula that includes revenues, market capitalization, profitiability and assets, amoung other factors. The Forbes Global 2000 includes 3 private oil firms as of 2008, Exxon, BP and Shell in the top 10. (interestingly, has three banks in the top 3 spots -- with the current lower market capitalization of the financial sector due to the ongoing 2008 credit crisis, it is likely the Forbes 200 2009 version may drop financials from the top three spots). The Forbes Global 200 ranks publicly-held and privately-held firms only.
It should be noted that in the energy world, the largest energy firms are mainly national oil firms -- otherwise known as "NIOCs", 100% owned or partially owned by governments. Saudi Aramco, the national oil company of Saudi Arabia, is by far the largest oil firm in the world, according, to the Petroleum Intelligence Weekly top 50 (PIW 50), which can be found here: http://www.energyintel.com/documentdetail.asp?document_id=218175 Saudi Aramco's #1 ranking in terms of size in the PIW 50 is based on Saudi Arabia's massive size as an oil producer: Saudi Aramco expects to produce over 9M barrels per day of oil and natural gas liquids in 2008, and boasts oil reserves of approximately 250 billion barrels, a full quarter of known conventional oil reserves. In comparison, the privately owned Exxon Mobil produces approximately 3M barrels per day of oil (including natual gas in terms of oil equivalent barrels) and boasts reserves of approximantely 21 Billion barrels, including affliates. From these measures, it is clear that Saudi Aramco is the largest oil firm in the world in terms of energy production.
If the Forbes Global 2000 included both government-owned firms in addition to publicly held firms, it is likely that Saudi Aramco would be number 1 in the Forbes Global 200 list, as it is clearly a larger energy firm than Exxon Mobil.
Other national oil firms also boast very high oil and gas production numbers. The majority stated owned Gazprom -- the equity of which can be purchased as the government only holds a majority share, and the rest trades -- produces approximantely 9.5M barrels per day oil equivalent in natual gas, not counting Gazprom's oil production subsidiary. Oddly, according to Forbes' Global 200 ranking, Gazprom places only 19th in 2006, even through in the energy world it is one of the heavy weights (PIW has been steadily increasing Gazprom's ranking in the top 50).
The relevence of this discussion is the fact that KazMunaiGas and Gazprom Neft are not currently on the radar of either the PIW 50 or the Forbes Gloabl 200. These firms are not very well known in international circles. However, KazMunaiGas boasts very high reserve numbers, as mentioned in the previous article - over 2 Billion barrels of oil equivalent. In comparison, Marthon Oil, which is ranked 34th on the PIW 50, has reserves of approximately 1.2 Billion barrels of oil equivalent. Gazprom Neft also has reserves over 2 billion barrels, and, as argued in both previous articles, both KazMunaiGas and Gazprom Neft and growing rapidly in terms of reserves and production, while most western oil firms are struggling to maintain production. Going forward, it is expected that both KazMunaiGas and Gazprom Neft should gain recognition on both the Forbes Global 2000 and the PIW 50, which should boast investor recognition and probably market capitalization.