Petroleum extraction in the context of "Global oil supply"

This is a list of countries by oil extraction (i.e., petroleum extraction or "production"), as compiled from the U.S. Energy Information Administration database for calendar year 2023, tabulating all countries on a comparable best-estimate basis.

Compared with shorter-term data, the full-year figures are less prone to distortion from periodic maintenance shutdowns and other seasonal cycles.

Unconventional (oil and gas) reservoirs, or unconventional resources (resource plays) are accumulations where oil and gas phases are tightly bound to the rock fabric by strong capillary forces, requiring specialized measures for evaluation and extraction.

The McKittrick Oil Field is a large oil and gas field in western Kern County, California. The town of McKittrick overlies the northeastern portion of the oil field. Recognized as an oil field in the 19th century, but known by Native Americans for thousands of years due to its tar seeps, the field is ranked 19th in California by total ultimate oil recovery, and has had a cumulative production of over 303 million barrels (48,200,000 m) of oil. The principal operators of the field as of 2008 were Chevron Corp. and Aera Energy LLC, but many independent oil exploration and production companies were also active on the field. The California Department of Oil, Gas and Geothermal Resources (DOGGR) estimates approximately 20 million recoverable barrels of oil remain in the ground.

Produced water is a term used in the oil industry or geothermal industry to describe water that is produced as a byproduct during the extraction of oil and natural gas, or used as a medium for heat extraction. Water that is produced along with the hydrocarbons is generally brackish and saline in nature. Oil and gas reservoirs often have water as well as hydrocarbons, sometimes in a zone that lies under the hydrocarbons, and sometimes in the same zone with the oil and gas. In geothermal plants, the produced water is usually hot. It contains steam with dissolved solutes and gases, providing important information on the geological, chemical, and hydrological characteristics of geothermal systems.Oil wells sometimes produce large volumes of water with the oil, while gas wells tend to produce water in smaller proportions.

As an oilfield becomes old, its natural drive to produce hydrocarbons decreases leading to decline in production. To achieve maximum oil recovery, waterflooding is often implemented, in which water is injected into the reservoirs to help force the oil to the production wells. In offshore areas, sea water is used. In onshore installations, the injected water is obtained from rivers, treated produced water, or underground. Injected water is treated with many chemicals to make it suitable for injection. The injected water eventually reaches the production wells, and so in the later stages of water flooding, the produced water's proportion ("cut") of the total production increases.