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How do aboveground retorts produce synthetic crude oil from oil shale?

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petroleum production A semisubmersible oil production platform operating in water 1,800 metres (6,000 feet) deep in the Campos basin, off the coast of Rio de Janeiro state, Brazil.

Aboveground retorting, or ex situ processing, is a method used to produce synthetic crude oil—also known as kerogen oil—from oil shale through the process of pyrolysis.12

The production process involves four primary steps:
* Mining and Crushing: The oil shale is mined and crushed into specific sizes (lumps or fines) suitable for the retort vessel.32
* Retorting: The crushed shale is heated in an oxygen-free environment to temperatures typically ranging from 480 to 550 °C (900–1,020 °F). This intense heat breaks the chemical bonds of the kerogen macromolecules within the rock, liberating liquid and gaseous [hydrocarbons].12
* Condensation: The released oil vapors are captured and liquefied in a series of condensers.2
* Upgrading: The resulting synthetic crude is upgraded to remove impurities such as nitrogen, sulfur, and oxygen compounds.13

Various heating approaches are used in these retorts, including internal combustion, hot-recycled-solids, conduction through a wall, and the injection of externally generated hot gases or reactive fluids.1