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oil drilling

According to the Department of Natural Resources, the United States consumes more than 20 million barrels of petroleum products every day, and over half of them are in the form of gasoline. While you may not often think about the gasoline that’s filling up your vehicle up, has the way that it’s made ever crossed your mind? Our fleet fuel card company dove into it:

Crude Oil

Gasoline starts off as crude oil, which is a dark, viscous liquid found inside pockets of the earth. This liquid is made from the remains of tiny aquatic plants and animals that lived millions of years ago. Over time, sediment covered these remains and under natural pressure and high temperatures, they were liquified and trapped inside the ground.

Once a team of oil drillers finds an underground area of crude oil, they drill into the porous rocks (where oil is usually trapped) to excavate it. These oil wells can be several hundred to several thousand feet deep in the earth and each well contains an unknown amount of oil.

In its natural form, crude oil contains many different molecules, which makes it insufficient as fuel. In order to make it useable, these molecules must be separated into smaller portions and refined to create gasoline, heating oil, jet fuel, propane, natural gas, and many other items.


In order to separate crude oil into smaller molecule chains, the oil must go through fractional distillation. The oil is first heated to over 600 degrees Fahrenheit, which causes all but the largest molecules to evaporate. As the vapors rise, they’re cooled and condensed, which creates gasoline (while heavier molecules condense further down in the distillation tower). However, the gasoline still needs to be refined in order to be used.

One popular refining process is the catalytic cracking process, which uses high temperatures, high pressure, and additives to change the chemical makeup of the gasoline. Another is polymerization, which combines small, vapor molecules with larger ones to create a usable fuel.


Once refined, several more chemicals are added to gasoline in order to run smoothly in vehicular engines. After this, it’s rated based on the ratio of isooctane and heptane. For example, an 87 octane gasoline contains 87% isooctane and 13% heptane. The more isooctane, the less knocking it causes when it runs through an engine.

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