Key Difference – Shale oil vs Crude oil
Shale oil and crude oil are two types of energy sources. Of these, crude oil is well-known as the main energy source for several decades but, shale oil is considered as an emerging energy source that can be used as an alternative solution for high crude oil demand in the market. The key difference between shale oil and crude oil is in its composition; Shale oil contains relatively large quantities of sulfur, nitrogen, and oxygen than that of crude oil. But, the cost of production of shale oil is comparatively low.
What is Shale Oil?
The shale oil is also known as “light tight oil” and is produced from oil shale rock fragments by the process of pyrolysis (Thermochemical decomposition of organic material at elevated temperatures in the absence of oxygen (or any halogens). It is an irreversible process which involves the simultaneous change of chemical composition and physical phase), hydrogenation (a chemical reaction between molecular hydrogen (H2) and another compound or element, usually in the presence of a catalyst) or thermal dissolution (a chemical decomposition caused by heat). The organic matter in the rock (kerogen) is converted into synthetic oil and gas during these processes. These processes produce an unconventional oil which can be readily used as a fuel or can also be improved to achieve feedstock specifications by doing additional purification methods. This is done by adding hydrogen and removing other impurities such as nitrogen and sulfur. The resulting product can be used for the same applications as derived from crude oil.
The production of shale oil is a great achievement for the global oil crisis. Because, it is a relatively low cost unconventional resource, it can be spread all over the world to address the global energy problem.
What is Crude Oil?
Crude oil is a hydrocarbon mixture having very simple to more complex molecular structures with long chains and higher molecular weights. They are naturally present in liquid form and can be obtained by natural gas by condensation or extraction. Crude oil is the world’s largest energy provider and it is considered as a non-renewable energy source. The world is at a risk since the oil consumption rate is very much higher that its regeneration rate.
It takes such a long time to produce crude oil by bacterial transformation of organic matter such as carbohydrates and proteins from plant and animal origin.
What is the difference between Shale Oil and Crude Oil?
Composition of Shale Oil and Crude Oil:
Shale Oil: Shale oil mainly contains kerogen (more than 95%) and small amount of oxygen, nitrogen and sulfur.
Crude Oil: Crude oil products can be categorized as follows.
| Light Distillates | Middle Distillates | Heavy Distillates |
| Liquid petroleum gas (LPG) | Kerosene | Heavy fuel oils |
| Gasoline or Petrol | Automotive and rail-road diesel fuels | |
| Heavy Naphtha | Residential heating fuel | |
| Light Naphtha | Other light fuel oils |
Extraction Process of Shale Oil and Crude Oil:
Shale Oil: The shale oil extraction is an unconventional oil production process. It involves the conversion of kerogen in oil shale into shale oil by pyrolysis, hydrogenation, or thermal dissolution. The product obtained from these processes can be readily used as fuel or can be refined to remove impurities and to enhance its qualities.
The extraction process is usually performed above the ground. After mining the oil shale, it is treated providing other processing facilities.
Crude Oil: The most commonly used crude oil extraction process is started by drilling. After the extraction, it is refined to convert crude oil into useful products such as liquefied petroleum gas (LPG), gasoline or petrol, kerosene, jet fuel, diesel oil and fuel oils.
Image Courtesy:
1. Messel oil shale sideritic laminae By Gretarsson (Own work) [GFDL or CC BY-SA 3.0], via Wikimedia Commons
2. Oil well By Flcelloguy at the English language Wikipedia, [CC BY-SA 3.0], via Wikimedia Commons