A company's ability to produce crude oil depends on access to oil deposits, but it also depends on access to modern technology. The effects of rising world demand and higher prices since 2003 can be seen in the increased output of most of the companies on the list. Objectives

Privately held companies have the goal of maximizing shareholder value. The national oil companies of more developed nations, Statoil in Norway, and Petronas in Malaysia, for example, tend to follow a more commercially oriented strategy than the Nigerian National Petroleum Co. and Petroleos de Venezuela, where government objectives largely supplant commercial objectives, and the companies are under pressure to maximize the flow of funds to the national treasuries. However, in some cases technological factors make this strategy difficult. For some countries and their national oil companies, oil supply security means the ownership, or exclusive rights to, desired supplies of oil. Characteristics of National Oil Companies

Because national oil companies may be motivated by different objectives than private oil companies, their performance characteristics are also likely to be different. However, those firms, the international oil companies, hold a shrinking fraction of the world's reserve base. In the longer term, damage to the world oil market could be enhanced by the dominant position the national oil companies have in terms of potential reserve access. If the national oil companies do not undertake investment on this scale, and if they and their governments exclude the international oil companies from developing reserves in their countries, the world oil market could be supply-constrained in the future, and prices might be higher than if higher investment took place. The international oil companies may not have access to what they consider to be favorable prospects. For example, while an oil-producing nation's government might be willing to try to coerce private oil companies, they might be less willing to do so to a company directly tied to the U.S. government. If the national oil companies hold the title to ever greater portions of actual and potential oil reserves, production, and exploration and development activities, and if they are relatively less capable of utilizing those resources, oil supplies are likely to be relatively constrained in the future. The private international oil companies are unlikely to be able to counter national oil companies to preserve their own profit-seeking interests as well as those of the U.S. market, which requires adequate physical supply at moderate prices. Adnoc is the state-owned company of the United Arab Emigrates CNOOC is a 71% state-owned company of China INOC is the state-owned company of Iraq KPC is the state-owned company of Kuwait Libya NOC is the state-owned company of Libya NIOC is the state-owned company of Iran NNPC is the state-owned company of Nigeria ONGC is the 71.4% state-owned company of India PDVSA is the state-owned company of Venezuela Pemex is the state-owned company of Mexico Pertamina is the state-owned company of Indonesia PetroChina is the 90% state-owned company of China Petronas is the state-owned company of Malaysia QP is the state-owned company of Qatar Rosneft is the 75.16% state-owned company of Russia Saudi Aramco is the state-owned company of Saudi Arabia Sonatrach is the state-owned company of Algeria Statoil is the 70.9% state oil company of Norway
In the United States, the term "big oil companies" is likely to be taken to mean the major private international oil companies, largely based in Europe or America. However, while some of those companies are indeed among the largest in the world, by many important measures, a majority of the largest oil companies are state-owned, national oil companies. By conventional definitions, national oil companies hold the majority of petroleum reserves and produce the majority of the world's supply of crude oil. Since national oil companies generally hold exclusive rights to exploration and development of petroleum resources within the home country, they also can decide on the degree to which they require participation by private companies in those activities.
The national oil companies typically do not operate strictly on the basis of market principles. Because of their close ties to the national government, in many cases their objectives might include wealth re-distribution, jobs creation, general economic development, economic and energy security, and vertical integration. Although these objectives might be desirable from the point of view of the nation's government, they are unlikely to be equivalent to the maximization of shareholder value, the stated objective of the private international oil companies.
Differing objectives might be considered to be important only if they lead to different characteristics and outcomes, which is the case for the national oil companies. Many of these companies have been found to be inefficient, with relatively low investment rates. They tend to exploit oil reserves for short-term gain, possibly damaging oil fields, reducing the longer term production potential. Some also have limited access to international capital markets because of poor business practices and a lack of transparency in their business deals. High oil prices since late 2003 have masked the effect of some of these characteristics in the flow of oil revenues. However, if the price of oil moderates, the potential supply constraint related to the inefficient operations of the national oil companies may be a destabilizing factor in the world oil market.
A wide variety of policy directions can be taken to mitigate the potential challenge posed by the dominance of national oil companies. Demand management policy can reduce the U.S. dependence on imports. The U.S. government can use its political influence to try to encourage nations not to use national oil companies to forward the aims of the government, but to follow commercial practices to maximize revenue flows. An expanded supply of oil could be encouraged as a condition for trade and aid agreements in some cases. Finally, promoting international trade and recognized commercial practices could be encouraged.