Short answers, pulled from the story.
Petroleum, also known as crude oil, is a naturally occurring yellowish-black liquid mixture found in geological formations and made primarily of hydrocarbons. By weight it is 83 to 85 percent carbon and 10 to 14 percent hydrogen, with smaller amounts of nitrogen, oxygen, sulfur, and trace metals such as iron, nickel, copper, and vanadium.
Petroleum is a fossil fuel formed over millions of years from the anaerobic decay of buried prehistoric organisms, particularly plankton and algae. Buried organic matter first becomes a waxy material called kerogen, which then transforms into liquid and gaseous hydrocarbons through a process called catagenesis at depths around one kilometre, where temperatures reach about 50 degrees Celsius.
The first intentional well for commercial oil extraction was hand-dug in 1853 by Ignacy Lukasiewicz in Bobrka, Poland. The first oil well in the Americas was drilled in 1859 by Edwin Drake at the Drake Well in Cherrytree Township, Pennsylvania, while Canada's first commercial well became operational in 1858 at Oil Springs, Ontario.
The word petroleum comes from Medieval Latin meaning literally rock oil, combining the Latin words for rock and oil, which trace back to the Greek petra and elaion. The term took root in monasteries in southern Italy by the end of the first millennium as an alternative for the older word naphtha.
According to a 2021 estimate, the world consumes about 97.26 million barrels of oil each day. Around 90 percent of vehicular fuel needs are met by oil, and petroleum makes up about 40 percent of total energy consumption in the United States.
Burning petroleum accounts for about a quarter of annual global greenhouse gas emissions, helping push atmospheric carbon dioxide above 415 parts per million. Oil spills from tanker accidents, such as the Exxon Valdez and Deepwater Horizon spills, have damaged ecosystems in Alaska, the Gulf of Mexico, the Galapagos Islands, and France.