The extraction of shale oil (also known as tight oil) is an unconventional process of obtaining synthetic oil and gas. Oil shale is a type of sedimentary rock which is rich in organic content (bituminous stuff called kerogen). The organic content has to be treated to extract shale oil.

The oil shale (rock containing the kerogen) releases the oil when it is heated in the absence of oxygen; a process called pyrolysis. The processes of the formation of petroleum and oil shale are similar, only in the latter, the pressure and temperature were not as high. As a result, the organic material remains attached to the rock. Did you know that oil shale contains enough organic material to enable it to burn without additional processing? As a result, it has been nicknamed the “rock that burns”.

Two ways to extract shale oil

There are two ways of extracting shale oil: “in-situ retorting” and “surface processing”. In in-situ retorting, hot liquids are pumped into the reserve. Over time, the shale gets heated and the kerogen begins to soften. The rock remains where it is. The near liquid kerogen (called shale oil at this point) is then extracted to the surface and processed to get synthetic crude oil.

In surface processing, the oil shale is mined and made to undergo pyrolysis (heating to extreme temperature in the absence of oxygen). At about 700 degree Celsius, the kerogen liquefies and seeps out of the rock. The shale oil is later processed to create synthetic crude oil. Shale oil extraction is a growing practice and a direct result of scarce petroleum reserves.

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