Crude Oil: Properties & Uses

Instructor: Sarah Friedl

Sarah has two Master's, one in Zoology and one in GIS, a Bachelor's in Biology, and has taught college level Physical Science and Biology.

Crude oil is an important fossil fuel that we use in many aspects of our daily lives. In this lesson we discuss what crude oil is, where it comes from, what it's used for, and why some are concerned about its relationship with the environment.

What and Where Is Crude Oil?

When you drive your car, turn on a light, or cook something on a stove, do you ever stop to think about the energy powering those things? It comes from fossil fuels, which formed over millions and millions of years from the remains of organisms that lived a long time ago. Through a long process they went from dead plants and animals to things like coal, gas, and the focus of this lesson, crude oil.

We find crude oil trapped in sedimentary rock in Earth's crust. It's a mixture of different organic molecules called hydrocarbons, which formed from dead marine life that lived long ago. The organisms, sediments, and other environmental factors that are involved in the formation of crude oil vary from location to location, which is why the composition of crude oil may vary too.

How We Get Crude Oil

There are three main ways that crude oil is extracted from the ground. The first is primary recovery. This method collects oil that has naturally risen to the surface of the earth from pressure underground or with pumps that help bring oil to the surface. This method only collects about 10% of the oil from a reservoir, so it's not very efficient.

Crude oil may need to be pumped to the surface to be collected from a reservoir
oil pumpjack

Next is secondary recovery. This occurs after the initial phase of drilling and involves injecting gas or water into the source to displace, or move, the oil to the surface for collection. Because more oil is brought to the surface, 20-40% of the reservoir's oil can be collected this way.

Finally we have enhanced oil recovery(EOR), which can recover 30-60% of a reservoir's supply. EOR is becoming more and more necessary as the easy to collect oil recovered in primary and secondary extraction is running low.

There are three types of EOR. First is thermal recovery, which like it sounds involves the use of heat. Specifically, injecting steam to make the oil thinner and help it flow more easily. The second is gas injection which of course uses gas. The gas expands inside the reservoir and pushes oil upward. Some gases may be used to thin the oil and make it flow more easily, similar to thermal recovery. This is the most commonly used type of EOR in the U.S. Finally we have chemical injection. This method uses chemicals called polymers that are mixed with water to decrease surface tension that can prevent oil from moving through the reservoir, as well as to increase the effectiveness of waterflooding, another name for water injection.

Using Crude Oil

Crude oil is used for numerous products but it first has to be refined or separated into usable petroleum products. Through this process, we actually end up with a greater volume than what we started with, called a processing gain. This happens because the products that the oil is separated into have larger individual volumes than the initial crude oil being refined.

One of the main products we get from crude oil is gasoline for our cars
gas pump

The list of what we get from refined crude oil is a very long one! Everything from oil, gasoline, and tires for your car, to jet fuel, diesel fuel, kerosene, plastics, and even asphalt. Petroleum products are in lots of places you don't expect either. Synthetic fibers, sunscreen, medications, hairbrushes, cosmetics, and even your smart phone and sunglasses. As you can see, crude oil is very important resource to just about everyone!

Environmental Concerns

A major issue with crude oil is that it takes a very long time to form but only a short amount of time to use. It's estimated that at the rate we're going, the supply of crude oil available on Earth will run out in about 30 years!

Additionally, when we burn crude oil products, such as using gas in our cars, we are putting that oil in places like the atmosphere in other forms, like greenhouse gases. This is also occurring at an unsustainable rate. Global warming and other climate change issues are directly related to the burning of fossil fuels, and crude oil products are no exception.

When an oil spill occurs there can be detrimental effects to the surrounding environment
bird after an oil spill

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