The ins and outs of oil refining

An overview of crude oil, including its constituent hydrocarbons and refinement outputs

The mixture is primarily composed of molecules of carbon and hydrogen atoms bonded into a variety of shapes and lengths, giving each different chemical properties, such as boiling points. Refining can remove elemental impurities—such as sulfur—after hydrocarbons are separated, ensuring the resulting products can be used effectively in other machines, such as car engines.

To use the various chemicals in crude oil, they must often be cracked—broken down into smaller molecules—to make their processing easier in everyday machines.

View the 45 gallons of refined products created from each 42-gallon barrel of crude oil

More than 85% is refined into fuels, such as gasoline and diesel, while about 10% is converted into raw materials for plastics, synthetic rubbers, and other essential products, such as lubricants. Because the majority of these products are less dense than the starting crude oil and additional inputs are introduced during the refining process, there is a processing gain of three gallons.

See where the 100 million barrels of crude oil the world consumes daily end up.

The winding journey from Standard Oil to the modern oil industry

Standard Oil’s impact on the business world can be clearly seen today in oil giants like Exxon and Chevron. But the journey from the Rockefellers’ trust to the modern firms was a windy road. After the Supreme Court ordered Standard Oil’s break up, the first step saw it separate into many state-based companies like Standard Oil of California and the Ohio Oil Company. Visualize it here.

Crude oil is the type of oil used to create fuel like gasoline, heating oil, and more

Technically speaking, crude oil is unrefined petroleum. This article dives into the different ways it’s categorized (by density, sulfur content, and origin), and how the combinations of these types of oil are used.

The separation of crude oil into petroleum products begins by boiling it in a distillation tower, where constituent hydrocarbons are separated into layers based on the temperatures at which they boil.

View a sample of objects surprisingly derived from crude oil, including chewing gum and lipstick

Crude oil processing produces a variety of fuels and the building blocks for plastics, but it also distills out the hydrocarbons used to make aspirin, Teflon, vinyl, crayons, candles, Tupperware, roofing shingles, asphalt pavement, hair dye, anesthetics, food-grade lubricants, polyester, synthetic rubber, and resins for items like dentures.

How crude oil is split across oil markets based on geographic origin

Brent, West Texas Intermediate, and Dubai are the three crude oil classes and differ in terms of typical refinery uses, density, sulfur content, and suitability for financial benchmarking. Brent, which originates in the North Sea, is traders' go-to benchmark, in part, because it is easily shipped and politically stable, and used to price most of the crude sold internationally.

Understanding why the US can't use its own crude oil and depends on global markets

Before advancements in fracking technology made lighter shale oil readily available, US refineries had been built and optimized for decades to process heavier oil from other countries with high profitability. Despite being able to refine lighter oil, US oil companies can operate with better margins by exporting it to other nations whose refineries are optimized for it and importing heavier oil, for which the US has the infrastructure.

How Standard Oil created Chevron and ExxonMobil

Standard Oil was eventually ordered to separate into 34 different entities, and over the following years, those 34 companies merged into what is now called the “Big Four” in the oil industry.

Despite the misconception that it comes from dinosaurs, crude oil forms when microorganisms, such as algae and plankton, are subjected to high pressure and high temperature while buried under layers of sediment.

Oil markets are seeing higher costs and lower prices amid tech breakthroughs

Experts say oil demand has not yet reached its peak. Recent technological breakthroughs in the oil industry include advances in drilling and extraction, as well as subsurface technologies.

Standard Oil used vertical integration to create an empire

“Vertical integration” is a modern business phrase that refers to a company taking on multiple stages of production—but John D. Rockefeller pioneered it with his Standard Oil company, employing its own plumbers and handling its own oil transportation.

How disruptions in oil markets can drive up the price of everyday goods

Most types of plastic are made from polymers derived from chemicals produced by the processing and refining of crude oil and natural gas. Spikes in the cost of either fossil fuel raise the cost of wrappings, tubs, and other plastic containers for products.

Demystifying the claim that crude oil is inorganically created and a renewable resource

The abiogenic petroleum theory holds that fossil fuels originate in Earth's mantle and are constantly replenished, rather than formed by microorganisms over millions of years. While inorganic chemical processes can produce simple hydrocarbons, the range of complex molecules found in crude oil suggests an origin from a diverse set of organisms. Isotope analyses of these molecules also support the model that they originated from living things that preferentially take up certain isotopes over others.

A guide to crude oil and natural gas extraction, from rig site preparation to land restoration

Requirements for traffic plans, access roads, and noise barriers vary by state and local laws, but once the rig site is prepared, the rig is assembled and digs a well that is then encased in steel and cement to protect groundwater reservoirs. After drilling and testing the extraction pipe, fracking fluid is injected into the rock to create cracks where crude oil resides, allowing it to be pumped out.

Oil shocks, war, and the 1970s crisis that remade American energy and economics

The oil crises of the 1970s—fueled by Middle East conflict and OPEC's dominance—triggered inflation, price controls, and policy failure. But they also accelerated fracking, alternative energy, and the rise of free-market economics.

While major oil spills result from accidental pipeline ruptures or damage to transportation vessels or rigs, as much as half the oil that reaches coastlines has naturally leaked from the seafloor.

Oil's legacy: fueling industrial growth and shaping imperial strategies

This episode of The Rest Is History podcast traces oil's pivotal role—from fueling industrial growth to steering imperial power. It also examines how access to oil shaped US politics, World War II, and sparked the creation of OPEC following the Suez Crisis.

The US shipped nearly 4 billion barrels of oil abroad in 2024

More than half of the US’s oil is exported as the country produces mainly light, sweet crude but has many refineries that handle heavy, sour types.

View a breakdown of worldwide oil production since 1900, mostly led by the US

When analyzing the production of crude oil, shale oil, oil sands, and condensates since the start of the 20th century, Saudi Arabia produced more crude oil only in 1977, from 1979 to 1981, and from 1991 to 2016. Nations such as Iraq and the United Arab Emirates produced much smaller quantities than both Saudi Arabia and the US.

OPEC often intervenes to influence the price of oil

This guide explains how investing in oil works with in-depth explanations of each of the forces that control oil’s price. Oil is unique as a commodity in part because of OPEC’s role in regulating its price.

Explore a timeline of US dependence on crude oil from 1850 to 2023

Oil dependence began with the rise of oil as a commodity, followed by an era of geopolitical competition for the resource after World War II. The domestic fracking boom, which started around 2006, was driven by a desire to reduce the nation's dependence on international adversaries for energy.

An overview of bioremediation, which can help clean up oil spills, mining waste, and some plastics

The umbrella term refers to a variety of techniques that use organisms to remove harmful substances from an environment or break them down into nontoxic compounds. Because the availability of certain resources can limit the growth of these organisms and impair bioremediation efforts, nutrients such as fertilizers can be deployed to accelerate cleanup.

Trace the rise of oil: from early drilling to today’s global power

This animated map video vividly illustrates how petroleum shaped global politics and industry—from 18th-century uses and 19th-century drilling booms in North America to today’s OPEC strategies, shale revolution, and geopolitical oil influence.

Oil and natural gas from fracking is considered unconventional

This method forcibly extracts fossil fuels from tightly packed rocks, where they form from organic matter that has undergone extreme heat and pressure. Conventional drilling, on the other hand, waits for the oil and gas to escape from shale and accumulate in more porous and permeable rocks, such as limestone.

See a timeline that shows how volatile oil prices have been for decades, from OPEC-led embargoes in the 1970s and shale surges in the 2000s to the US flipping to become a net oil exporter in 2020.

The US exported more crude oil and petroleum products than it imported in 2025

In fact, the US has been exporting more oil and petroleum products than it imports since August 2021. Petroleum and petroleum product exports totaled about 10.7 million barrels per day, whereas imports totaled about 7.9 million barrels per day.

The recorded history of crude oil use dates back about 5,000 years, with the Babylonians using it to waterproof their boats and as mortar in the construction of structures.

Iran's 1979 revolution sparked a second oil shock—and reconfigured global energy markets.

The history of the Rockefellers in 60 seconds

John D. Rockefeller—the world's first billionaire—once controlled 90% of the US oil refining market, built Standard Oil through vertical integration, and used his fortune to fund universities, museums, and landmarks like Rockefeller Center.

A look at types of crude oil, distinguished by properties like heaviness and sweetness

API gravity is a unit that describes how heavy or light a crude oil sample is based on its density, with higher values indicating lighter, more valuable oil that requires less processing. The sweetness of crude oil refers to the amount of sulfur it contains, where sour crude oil requires more extensive treatment to remove the more abundant sulfur and sweeten it.

The price of crude oil accounts for roughly half of the price displayed at the gas pump

Decommissioned oil rigs have been repurposed into artificial reefs that serve as nursery habitats for fish, corals, sponges, and other invertebrates in the decades since their installation.

Review the health effects of living near oil refineries, including increased respiratory risks

An analysis of 54 studies published between 1977 and 2024 in 15 international regions found evidence that proximity to refineries increased the risks of leukemia, asthma, bronchitis, and respiratory symptoms. Several studies also identified worse cardiovascular function in children and adults living near refineries, alongside other acute and chronic health impacts.

Learn about unconventional ways to clean up crude oil, including using moss and chickens

Studies show that microorganisms in chicken manure can break down the hydrocarbons in crude oil without producing toxic by-products. Scientists have also explored avoiding the environmental risks of chemical dispersants and synthetic adsorbents by using human hair and peat moss to adsorb crude oil, which can be taken up by their cuticles and porous structures, respectively.

Standard Oil's predatory business practices included temporarily operating at a loss to drive competitors out of business

Rockefeller's oil monopoly had a dark side, including cutting oil prices so low that Standard Oil was sometimes temporarily operating at a loss in order to drive competitors out of business.

Fracking provides access to fossil fuel reserves locked in underground rock

Using a pressurized fluid mixture that is over 90% water, cracks are created in shale about 2 miles deep to release trapped oil and natural gas. The process uses an average of 3 to 6 million gallons of water per well, which can strain local water supplies.

How chemical recycling could create 'infinite' plastic

The way we normally recycle plastics is a downward spiral of waste and degraded materials, but there is another option—turning plastic back into the oil it was made from.

The Seven Sisters were a dominant midcentury Western oil consortium

Amid the fallout of World War II, Western multinational corporations expanded their control of the production of oil across the oil-rich Middle East, earning the pejorative nickname of the Seven Sisters. In the 1970s, the group’s role diminished as nationalist movements pursued sovereign control of the oil.

Why have gas prices surged nearly 27% since the Iran war began?

Oil passing through the Strait of Hormuz makes up only about 7% of US crude imports. However, crude oil prices account for 51% of the cost of a gallon of gas in the US. US refiners pay the Brent crude futures price, even for domestic drilling.

Hear Steve Ballmer explain how US gas prices are affected by the global price of oil.

The science (and scams) behind essential oils

Essential oils are a big business, with industry estimates pegging its market size at $10B last year—a number expected to double by 2030. These distilled plant compounds have a long history of both legitimate and exaggerated uses, and many marketed oils are, as the author of this long read claims, just selling wish fulfillment. Revisit some of the history and contemporary use of essential oils with this piece.

Fracking has led to an increased global oil supply, contributing to lower oil prices

Fracking technology has significantly increased how much crude oil the US produces. As more countries adopt fracking technology, there could be an increased downward pressure on prices—although fracking has been widely criticized for its negative environmental impacts.

The world derives more of its energy from oil than from any other resource

Coal and gas are second and third, respectively, in terms of where the bulk of the world’s energy consumption stems from. These interactive charts can help you visualize where the world sources the most of its energy.

The story of the first commercial US oil well and why crude oil is measured in barrels

The 1859 oil discovery in Titusville, Pennsylvania, sparked a boom in oil exploration and production to meet the demand for kerosene lamp fuel. Because the 42-gallon barrel was a readily available container already in use for shipping fish, butter, wine, and other goods, it was adopted by the Petroleum Producers Association in 1872 and by both the US Geological Survey and the US Bureau of Mines in 1882.

A case study of how engineers and geologists at Tullow Oil look for oil reserves

An analysis of surface rocks using aerial and satellite imagery can help narrow the search for crude oil by identifying basins where sedimentary layers have compacted—a key process in oil formation. Surveys that look for variations in Earth's gravitational and magnetic fields consistent with specific rock distributions, or that use sound waves reflected off rock layers—not unlike sonar underwater—can also help map subsurface geology.

The number of annual oil spills has dropped dramatically since the 1970s

Oil spills from oil tankers—which can have a sharp, short-term impact on oil prices—have become increasingly rare over the decades in part because of stricter regulations.

How the Rockefellers' wealth evolved over time

The Rockefellers built one of the most powerful business empires in US history. By the early 1900s, their company, Standard Oil, controlled over 90% of the US oil market.