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Where Our Oil Comes From

Did you know?

OPEC and Persian Gulf countries are not the same.

The Organization of the Petroleum Exporting Countries (OPEC) was organized in 1960 to negotiate with oil companies on matters of oil production, prices, and future concession rights. Of the 12 countries in OPEC in 2015, only 6 of them are in the Persian Gulf.

OPEC countries Persian Gulf countries
  • Iran
  • Iraq
  • Kuwait
  • Saudi Arabia
  • Qatar
  • United Arab Emirates
  • Algeria
  • Angola
  • Ecuador
  • Libya
  • Nigeria
  • Venezuela
  • Iran
  • Iraq
  • Kuwait
  • Saudi Arabia
  • Qatar
  • United Arab Emirates
  • Bahrain
  • Oman

U.S. refineries obtain crude oil produced in the United States and in other countries. Different types of companies supply crude oil to the world market.

Where is U.S. crude oil produced?


Crude oil is produced in 31 U.S. states and in U.S. coastal waters. In 2015, about 65% of U.S. crude oil production came from five states:

  • Texas—37%
  • North Dakota—12%
  • California—6%
  • Alaska—5%
  • Oklahoma—5%

In 2015, about 16% of U.S. crude oil was produced from wells located offshore in the federally administered waters of the Gulf of Mexico.

Although total U.S. crude oil production generally declined between 1985 and 2008, annual production increased from 2009 to 2015. More cost-effective drilling technology helped to boost production, especially in Texas, North Dakota, Oklahoma, New Mexico, and Colorado.

Many countries produce crude oil

About 100 countries produce crude oil. In 2014, 47% of the world's total crude oil production came from five countries:

  • Russia—13%
  • Saudi Arabia—13%
  • United States—11%
  • China—5%
  • Canada—4%

Different types of oil companies supply crude oil

The world oil market is complex. Governments and private companies play various roles in moving oil from producers to consumers.

In the United States, companies produce crude oil on private and public land and offshore waters. The majority of these companies are independent producers, and they usually operate only in the United States. The other companies, often referred to as major oil companies, may have hundreds or thousands of employees and operate in many countries. Examples of major U.S. oil companies are Chevron and ExxonMobil.

Three types of companies supply crude oil to the global oil market. Each type of company has different operational strategies and production-related goals.

International oil companies (IOCs)

These companies, which include ExxonMobil, BP, and Royal Dutch Shell, are entirely investor owned and are primarily interested in increasing their shareholder value. As a result, IOCs tend to make investment decisions based on economic factors. These companies typically move quickly to develop and produce the oil resources available to them and sell their output in the global market. Although these producers must follow the laws of the countries in which they produce oil, all of their decisions are ultimately made in the interest of the company and its shareholders, not in the interest of a government.

National oil companies (NOCs)

These companies operate as extensions of a government or a government agency, and they include companies such as Saudi Aramco (Saudi Arabia), Pemex (Mexico), the China National Petroleum Corporation (CNPC), and Petroleos de Venezuela S.A. (PdVSA). These companies financially support government programs and sometimes provide strategic support. The NOCs often provide fuels to their domestic consumers at a lower price than the fuels they provide to the international market. They do not always have the incentive, means, or intention to develop their reserves at the same pace as investor-owned international oil companies. Because of the diverse objectives of their supporting governments, the NOCs pursue goals that are not necessarily market oriented. The goals of the NOCs often include employing citizens, furthering a government's domestic or foreign policies, generating long-term revenue to pay for government programs, and supplying inexpensive domestic energy. All NOCs that belong to members of the Organization of the Petroleum Exporting Countries (OPEC) fall into this category.

NOCs with strategic and operational autonomy

The NOCs in this category function as corporate entities and do not operate as extensions of their countries' governments. This category includes Petrobras (Brazil) and Statoil (Norway). These companies often balance profit-oriented concerns and the objectives of their countries with the development of their corporate strategies. Although these companies are driven by commercial concerns, they may also take into account their nations' goals when making investment or other strategic decisions.

OPEC members have a large share of world oil supplies

The Organization of Petroleum Exporting Countries (OPEC) is a group that includes some of the world's most oil-rich countries (see list of OPEC member countries in the Did you know? box). Together, these countries control about 73% of the world's total proved crude oil reserves, and in 2015 they produced 43% of total world crude oil. Each OPEC country has at least one NOC, but most also allow international oil companies to operate within their borders.

Last updated: December 19, 2016

How is crude oil found and produced?

Geologists preparing a hole for the explosive charges used in seismic exploration

Geologists preparing a hole for the explosive charges used in seismic exploration

Source: Stock photography (copyrighted)

Schematic of different types of oil and natural gas wells

Oil and gas wells image

Source: Wyoming State Geological Survey (public domain)

Schematic of the basic types of oil and natural gas deposits

Diatom image: Group of cleaned frustules

Source: Wyoming State Geological Survey (public domain)

The search for crude oil begins with geologists who study the structure and history of rock layers below the earth's surface to locate areas that may contain deposits of oil and natural gas.

Geologists often use seismic surveys on land and in the ocean to find the right places to drill wells. Seismic surveys on land use echoes from a vibration source at the surface of the earth, usually a vibrating pad under a special type of truck. Geologists can also use small amounts of explosives as a vibration source. Seismic surveys conducted in the ocean rely on blasts of sound that create sonic waves to explore the geology beneath the ocean floor.

If a site seems promising, an exploratory well is drilled and tested. If enough oil is found to make it financially worthwhile to pursue, development wells are drilled. The type of well that is drilled depends on the location, geology, and oil resource.

Advances in drilling and production technologies have increased U.S. oil production

In the past, a drilling rig drilled a single vertical well. Now, many directional or horizontal wells can be drilled from one location, or well pad, to access greater areas of oil- and natural gas-bearing rock.

Oil may flow to the earth's surface from natural pressure in the rock formation, or it may have to be forced out of the ground and up through a well. The type of geologic formation where the oil is located determines the technologies used to start the flow of oil and natural gas from the reservoir or resource-bearing rock into the wells.

Hydraulic fracturing is used to access the oil and natural gas contained in tiny pores of rock formations composed of shale, sandstone, and carbonate (limestone). Hydraulic fracturing breaks up the rock in the formations and creates pathways that allow oil and natural gas to escape from the rock layers. Hydraulic fracturing involves forcing water, chemicals, and sand or other proppants (materials used to keep the pathways open) under high pressure into the wells. Steam, water, or carbon dioxide (CO2) can also be injected into a rock layer to help oil flow more easily into production wells.

Once the oil has been collected from wells in a production field, the oil is transported by pipelines, barges, trains, or trucks to refineries or to ports for transport on oil tankers to other countries.

Conventional and unconventional production

Production of crude oil and natural gas is sometimes called conventional production or unconventional production. Conventional production generally means that crude oil and natural gas flow to and up a well under the natural pressure of the earth. Unconventional production requires techniques and technologies to increase or enable oil and natural gas production beyond what might occur using conventional production techniques. In the United States, most of the new oil and natural gas production activities on land use unconventional production technologies.

Tight oil production

The U.S. oil and natural gas industry uses the term tight oil to mean the different geologic formations producing oil at a specific well. Tight oil is produced from low-permeability sandstones, carbonates (for example, limestone), and shale formations. The U.S. Energy Information Administration (EIA) uses the term tight oil to refer to all resources, reserves, and production associated with low-permeability formations that produce oil, including shale formations.

Notable tight oil formations include, but are not confined to:

  • Bakken and Three Forks formations in the Williston Basin
  • Eagle Ford, Austin Chalk, Buda, and Woodbine formations along the Gulf Coast
  • Spraberry, Wolfcamp, Bone Spring, Delaware, Glorieta, and Yeso formations in the Permian Basin
  • Niobrara formation in the Denver-Julesburg Basin

Last updated: November 21, 2016