Decoding API Gravity: How it Defines Crude Oil Types

October 25, 2023by Toluwanimi

When it comes to the world of crude oil, the term “API gravity” often floats around in technical discussions, leaving many wondering what it really means and why it matters. API gravity is not just another scientific jargon; it’s a crucial parameter that defines the characteristics and applications of different crude oil types. In this article, we will decode API gravity, explore its significance, and shed light on how it defines the diverse world of crude oil.

What Is API Gravity?

API, or American Petroleum Institute, gravity is a measure used to quantify the density of crude oil. It’s essentially a scale that tells us how light or heavy a particular crude oil is compared to water. The API gravity scale is based on the principle that liquids with API gravity values greater than 10 are lighter than water, while those with values less than 10 are heavier.

How Is API Gravity Calculated?

API gravity is determined by the following formula:

API Gravity = (141.5 / Specific Gravity at 60°F) – 131.5

In this equation, specific gravity is the ratio of the density of the crude oil to the density of water at a standard temperature of 60°F (15.6°C).

What API Gravity Reveals:

  • Crude Oil Types:
    • API gravity is a primary factor in classifying crude oil. Crude oils with higher API gravity values (greater than 30) are considered light oils, while those with lower values (less than 20) are categorized as heavy oils. This classification is crucial for determining their optimal uses.
  • Refining Suitability:
    • Lighter crude oils with higher API gravity values are easier to refine, requiring less processing to yield valuable products like gasoline and diesel fuel. Heavy crude oils, on the other hand, often require more extensive and complex refining processes.
  • Transportation and Storage:
    • API gravity also impacts the transportation and storage of crude oil. Lighter oils are easier to transport through pipelines and tankers, while heavier oils may require special handling due to their higher viscosity and density.
  • Market Value:
    • API gravity can influence the market value of crude oil. Lighter crude oils typically command higher prices due to their ease of refinement and greater versatility in producing valuable end products.
Real-World Examples:
  • Light Crude Oils: In Nigeria, Bonny Light Crude Oil is an excellent example of a light crude oil with a high API gravity value, typically around 35. This high API gravity makes it an attractive option for refiners, as it requires less processing and yields a greater percentage of valuable products like gasoline.
  • Heavy Crude Oils: heavy crude oil with lower API gravity values can be found in the Niger Delta region, specifically in oil fields like those producing “Forcados Blend Crude Oil.” This Nigerian heavy crude oil has a notably lower API gravity compared to lighter counterparts like Bonny Light Crude Oil.

API gravity is not just a number on a scale; it’s a defining characteristic that shapes the world of crude oil. It determines the types of crude oil, influences their refining processes, impacts transportation and storage logistics, and even affects their market value. As we continue to explore and harness the potential of crude oil reserves, API gravity remains a crucial parameter that guides decision-making in the oil and gas industry. Understanding API gravity is, therefore, a key step in navigating the complex landscape of crude oil exploration and production.