All articles starting with O
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Oil reserves in Venezuela
The oil reserves in Venezuela, also called Venezuelan oil reserves, are the world's largest proven crude reserves at about 303 billion barrels, mostly extra-heavy oil in the Orinoco Belt.
Oil Rivers Protectorate
The Oil Rivers Protectorate was a British protectorate, proclaimed in 1885 over the Niger Delta trading city-states in what is now Nigeria and named for its palm oil trade.
Oil Rocks Oil Field
Oil Rocks (Neft Daşları) is an offshore oil field and settlement in the Azerbaijani sector of the Caspian Sea, where the world's first offshore well was drilled in 1949.
Oil sands
Oil sands, also known as tar sands, are geologic deposits of sand, clay, water, and bitumen so viscous it will not flow to a well, found chiefly in northern Alberta.
Oil separator
An oil separator, also called a lubricant separator, is a pressure vessel in a refrigeration compressor's discharge line that removes entrained oil and returns it to the crankcase.
Oil shale
Oil shale, also known as kerogen shale or bituminous shale, is a sedimentary rock containing kerogen, a solid precursor of oil that converts to crude oil when heated.
Oil spill
An oil spill, also called an oil slick, is the release of liquid petroleum into the environment, most often the ocean, from tankers, pipelines, offshore drilling, or natural seeps.
Oil spill bioremediation
Oil spill bioremediation uses microorganisms, usually stimulated by added fertilizers, to break down petroleum hydrocarbons after spills, most often on aerobic shorelines after mechanical cleanup.
Oil tanker
The oil tanker, or petroleum tanker, is a merchant ship that carries products in bulk and, as of 2023, comprised nearly 36.9% of the entire global fleet.
Oil well
An oil well is a hole drilled into the earth to find or produce crude oil or natural gas, passing from drilling through casing, completion, and production to plugging.
Oil window
The oil window is the range of burial depth or thermal maturity within which a sedimentary source rock generates and expels liquid petroleum from kerogen.
Oil wrestling
Oil wrestling (yağlı güreş) is a traditional Turkish sport in which oiled pehlivan wrestlers in leather kispet try to turn an opponent's back to the ground; its Kırkpınar festival in Edirne, held since the 14th century, joined UNESCO's heritage list in 2010.
Oil-based mud
Oil-based mud is a drilling fluid with oil as the continuous phase and brine emulsified as droplets, used in rotary drilling for shale stability, lubricity, and high-temperature wells.
Oil-filled cable
An oil-filled cable is a high-voltage power cable in which paper insulation is impregnated with oil kept under continuous pressure, as self-contained or pipe-type designs.
Oil-filled transformer
An oil-filled transformer, also called an oil-immersed transformer, is an electrical transformer with its core and windings submerged in insulating oil that both insulates and cools.
Oil-for-Food Programme
The Oil-for-Food Programme (OFFP) was a UN program under Security Council resolution 986 (1995) letting sanctioned Iraq sell oil for food, medicine, and civilian goods; it ran December 1996 to November 2003, moved over $67 billion in oil revenue, and was later investigated for corruption by the Volcker Committee.
Oil-indexed pricing
Oil-indexed pricing sets the price of natural gas, especially LNG, as a formula tied to crude oil prices, and remains the traditional basis for long-term LNG contracts in Asia.
Oil-well cement
Oil-well cement is a Portland cement specified under API standards to seal the space between well casing and borehole, providing zonal isolation in oil, gas, and geothermal wells.
Oil–water separation membrane
An oil–water separation membrane is a porous, pressure-driven barrier that passes one phase of an oil–water mixture while rejecting the other, cleaning oily industrial wastewater or recovering oil.
Oil!
Oil! is Upton Sinclair's 1926-27 novel about the Southern California oil boom, following Bunny Ross, son of tycoon J. Arnold Ross, amid Teapot Dome-era corruption, labor strikes, and socialism; banned in Boston and loosely adapted as There Will Be Blood (2007).
Oiltanking
Oiltanking is a German tank storage company, a subsidiary of Marquard & Bahls, operating 64 terminals in 24 countries for crude oil, petroleum products, and chemicals.
Oilule Fluctus
Oilule Fluctus is a 900 km lava flow terrain (fluctus) on Venus at 22.0S, 79.0E in the Aino Planitia quadrangle, named in 1998 after the West Bulgarian wife of the thunder god.
Oily fish
Oily fish (fatty fish): fish with fat in the flesh, such as salmon, mackerel, herring, sardines, and trout; richest food source of EPA/DHA omega-3s and vitamin D, with recommended weekly intakes and mercury limits.
Oingo Boingo
Oingo Boingo, also known late in its career as Boingo, was a Los Angeles new wave band (1979–1995) led by Danny Elfman, descended from the Mystic Knights theatrical troupe, best known for Dead Man's Party and Weird Science.
Oiniadai
Oiniadai (Oiniades, Oeniadae) was an ancient Greek city of Acarnania at the mouth of the Acheloos river in Aetolia-Acarnania, western Greece, known for its 6.5 km polygonal walls, 4th-century BC rock-cut shipsheds, and large ancient theater.
Oinoe (Attica)
Oinoe (Οἰνόη), fortified Attic deme of the Hippothontis tribe in the Mazi Plain, northwest Attica; first town unsuccessfully attacked by Sparta in 431 BCE, with a rare rectangular 5th-century fortification near modern Mazi.
Oip Lightning
OIP Lightning, LP is a Delaware private equity fund managed by Odyssey Investment Partners of New York, which reported raising $1.287 billion from 16 investors in 2025.
Oiran (花魁)
Oiran (花魁) were the highest-ranked courtesans working in the pleasure quarters licensed by the Tokugawa shogunate during Japan's Edo period, above all in the Yoshiwara district of Edo, present-day Tokyo.
Oirat code of 1640
The Oirat code of 1640, known as Ikh Tsaaz (Great Code), is a Mongol-Oirat law code adopted at a 1640 congress of princes from Dzungaria, Khalkha Mongolia, and Kalmykia.
Oirat Invasion and the Defense of Beijing Treaty Negotiations
The Oirat Invasion and the Defense of Beijing Treaty Negotiations (也先入侵與議和) were the 1449 events in which the Oirat leader Esen captured Emperor Yingzong at Tumu and Beijing held.