Medium crude oil is a type of petroleum with an API gravity typically between 22° and 31°. It falls between light crude and heavy crude in terms of viscosity, density, and sulfur content. Medium crude is widely preferred in refineries because it balances a good yield of valuable fuels like gasoline and diesel while remaining easier to process than heavy crude.
Medium crude oil is a petroleum classification based on API gravity, typically ranging between:
- 22°–31° API
- Light crude (>31° API)
- Heavy crude (<22° API)
Medium crude offers an optimal balance between ease of refining and high yield of valuable middle distillates such as diesel, kerosene, and jet fuel.
Chemical Composition
Medium crude oil is a complex hydrocarbon mixture, primarily composed of:
- Paraffins (Alkanes): 30–50%
- Naphthenes (Cycloalkanes): 25–40%
- Aromatics: 10–25%
- Resins & Asphaltenes: 5–10%
Elemental Composition
- Carbon (C): 83–87%
- Hydrogen (H): 11–14%
- Sulfur (S): 0.5–2.5%
- Nitrogen (N): 0.1–0.5%
- Oxygen (O): 0.1–1.0%
- Trace Metals (Ni, V, Fe): ppm levels
Key Physical Properties
- API Gravity: 22°–31°
- Density @ 15°C: 0.87–0.92 g/cm³
- Viscosity @ 40°C: 10–100 cSt
- Pour Point: –10°C to +20°C
- Flash Point: >38°C
- Boiling Range: 30°C – >600°C
- Sulfur Content: Medium (0.5–2.5%)
Mechanical Properties (Industrial Context)
Although crude oil is a fluid, mechanical properties matter in storage, transport, and processing:
- Moderate viscosity → easier pumping than heavy crude
- Stable laminar flow in pipelines
- Reduced need for heating vs heavy crude
- Good natural lubricating properties
- Protects pumps, valves, and compressors
- Low compressibility
- Stable under pipeline pressure conditions
Refining & Processing Properties
- LPG & Light Gases: 2–5%
- Naphtha: 15–25%
- Kerosene / Jet Fuel: 10–15%
- Diesel / Gasoil: 25–35%
- Residue: 20–30%
Atmospheric Distillation Yields
| Product | Yield (%) |
|---|---|
| LPG & Light Gases | 2–5 |
| Naphtha | 15–25 |
| Kerosene / Jet Fuel | 10–15 |
| Diesel / Gasoil | 25–35 |
| Residue | 20–30 |
Applications
- Diesel (primary output)
- Jet fuel
- Gasoline
- Marine fuels
Typical Medium Crude Examples
- Arab Medium
- Urals Crude
- Oman Crude
- Basrah Medium
- Mars Blend
Medium crude oil represents the sweet spot of global petroleum refining—combining manageable processing complexity, high-value product yields, and strong compatibility with existing refinery infrastructure.
It remains one of the most commercially attractive crude categories worldwide.