Heavy Oil and Oil Sands

 What is Heavy Oil?

Heavy oil is a type of crude oil withh a higher density and viscosity than conventional oil. It is classified based on API gravity, which measures the relative density of oil.

Heavy Oil: API gravity between 10° and 22°

Extra-Heavy Oil: API gravity below 10°


Becasue of its high viscosity, heavy oil does not flow easily at reservoir conditions, requiring enhanced recovery methods.


What are Oil Sands?

Oil sands, also known as tar sands, are a mixture of sand, water, clay, and bitumen ( a highly viscous form of crude oil). Bitumen has an API gravity below 10°and is too thick to flow naturally, requiring heating or dilution for extraction and transport. Major oil sands deposits are found in Venezuela, Canada and Russia.

Global Distribution of Heavy Oil and Oil Sands

The world's largest heavy oil and oil sands reserves are concentrated in a few regions:

Venezuela (Orinoco Belt): The world's largest extra-heavy oil deposit, containing an estimated 1.2 trillion barrels of oil in place.

Canada(Alberta Oil Sands): Home to the world's largest oil sands reserves, primarily in the Athabasca, Peace River, and Cold Lake regions.

Russia: Significant heavy oil and bitumen deposits in Western Siberia and the Volga-Ural region.

United States: Heavy oil production mainly in California (Kern River, Midway-Sunset fields).

Middle East: Heavy oil fields in Oman, Iraq, and Kuwait.

Extraction and Production Methods


1. Surface Mining (for Oil Sands)

-Used when oil sands are close to the surface.
-Large-scale excavation removes sand, which is processed to extract bitumen.
-Requires extensive water and energy inputs.


2. Thermal Recovery Methods (for Heavy Oil and Deep Oil Sands)

-Steam-Assisted Gravity Drainage (SAGD): Injects steam to reduce bitumen viscosity, allowing it to flow to production wells.
-Cyclic Steam Stimulation (CSS): Also known as "huff-and-puff," involves alternating steam injection and oil production cycles.
-In-Situ Combustion: Injects air to ignite part of the reservoir, heating the surrounding oil and reducing viscosity.


3. Cold Production Methods

-Cold Heavy Oil Production with Sand (CHOPS): Used in unconsolidated reservoirs where oil and sand are produced together, improving recovery.

-Diluent Addition: Light hydrocarbons are mixed with heavy oil to reduce viscosity and improve pipeline 

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