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Viscosity Types Used in Petroleum Engineering

The viscosity of a petroleum sample or that of a blend of samples largely determines the suitability of that petroleum in commercial applications. According to Harvard University, the viscosity of liquid petroleum has an important effect on its kinematics and therefore its applications: more fluid petroleum is better in machine lubrication, for example, and thicker petroleum is more suitable for diesel fuel. Azer Abdullayev at Texas A&M University points out that the viscosity of various petroleum types changes with temperature. Dr. Jorge Gabitto and Dr. Maria Barrufet argue that petroleum obtained from one geographic region often has a very different viscosity than oil found in another.

The Effect of Viscosity on End Users
- Thin, less viscous is highly fluid and can move through pipes and around machinery with ease. Thick, highly viscous fluid resists movement and is more like a syrup than a pure liquid, but packs more energy into less space. The ultimate utility of a petroleum sample is largely dependent on its viscosity, and petroleum engineering is largely about separating oils into viscosity classes and refining the products into usable commercial products. Motor oils and gasoline are often derived from less-viscous petroleum, while heavy diesel fuel and paving materials like asphalt are derived from more-viscous sources.
Light, Sweet Crude
- Light, sweet crude is a highly fluid type of petroleum prized by petroleum engineers for its ability to act as an ideal fluid and be refined into high-value end products. Less viscous petroleum such as light, sweet crude can be refined into motor oils that provide lubrication and protection to sensitive machinery in a wide range of temperatures. It can also be refined into gasoline. Cosmetics and some pharmaceutical companies make use of less viscous petroleum and bring a high price on the market.
Heavy Crude
- Heavier crude petroleum is more plentiful and contains more energy per unit volume due to its high concentration of hydrocarbons. Because of this, it is ideal in bulk applications like asphalt and providing the fuel for oil-burning power plants. Petroleum engineers can work on heavy crude to separate less viscous sub-elements from its larger structure for use in higher value processes. Diesel fuel can be refined out of heavy, viscous crude.
Medium Viscosities
- Viscosity describes the willingness of a fluid to flow freely, and is analogous to the thickness of the fluid being described. As such it is measured on a scale and there are many gradations between light, sweet crude and heavy crude. Oil of medium viscosity can be used in lower-quality motor oils or in niche applications that benefit from utilizing cheaper hydrocarbons. It can also be separated into higher and lower viscosity portions and then routed by petroleum engineers for further processing.

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