The key difference between heavy oil and light oil is that heavy oil has a high viscosity and cannot flow easily, whereas light oil has a low viscosity and can flow freely.
The terms heavy oil and light oil are applied for crude oil. We can divide crude oil into these two groups according to the viscosity of the oil, which decides the ability to flow freely. Heavy oil cannot freely flow due to the high viscosity that comes from its high density, while light oil is the opposite of heavy oil and it has a low density which determines its free-flowing property.
What is Heavy Oil?
Heavy oil or heavy crude oil is a highly viscous oil that cannot flow freely at room temperature. This high viscosity is a result of the density of the oil. Heavy oil has a higher density and specific gravity compared to light crude oil. We can define a heavy oil as a liquid petroleum oil having an API gravity of less than 20 degrees. When considering the chemical properties of heavy oil, it gets has a high density and viscosity due to the presence of high molecular weight hydrocarbon compounds.
We can categorize heavy oils and asphalt as dense non-aqueous phase liquids or DNAPLs. These oils have low solubility, and also their density and viscosity are higher than that of water. Therefore, large spills of DNAPLs can quickly penetrate the full depth of an aquifer to accumulate at the bottom of a spill. Typically, heavy oil is similar to natural bitumen and oil sands.
Usually, heavy oil is asphaltic, and it contains asphaltenes and resins. These oils have a high ratio of aromatics and naphthalene to linear alkanes and high levels of NSOs (which include nitrogen, sulfur, oxygen and heavy metals). Moreover, a heavy oil contains a high percentage of compounds having over 60 carbon atoms along with high boiling points and high molecular weights.
What is Light Oil?
Light crude oil is a low viscous oil that can freely flow at room temperature. These oils have a low viscosity as well as a low specific gravity. Therefore, light oils have a high API gravity. This happens due to the presence of a high proportion of light hydrocarbon fractions. Generally. Light oil contains a low content of wax, and they are expensive compared to heavy oil because these oils can produce a high percentage of gasoline and diesel fuel upon conversion into products by an oil refinery.
We can give some examples for light oil that involves a wide variety of benchmark crude oils are light oils. E.g. West Texas intermediate in North America, which has an API gravity of about 39.6 degrees. The most common light oils among these West Texas intermediates include Brent Crude, Dubai Crude, etc.
What is the Difference Between Heavy Oil and Light Oil?
Heavy oil or heavy crude oil is a highly viscous oil that cannot flow freely at room temperature. Light crude oil is a low viscous oil that can freely flow at room temperature. Therefore, the key difference between heavy oil and light oil is that heavy oil has a high viscosity and cannot flow easily, whereas light oil has a low viscosity and can flow freely.
The below tabulation lists the differences between heavy oil and light oil for side by side comparison.
Summary – Heavy Oil vs Light Oil
Petroleum oils can be divided into two groups as heavy oils and light oils through observing the flow properties and viscosity. The key difference between heavy oil and light oil is that heavy oil has a high viscosity and cannot flow easily, whereas light oil has a low viscosity and can flow freely.
1. “Light crude oil.” Wikipedia.