Union process
The Union process was an above ground shale oil extraction technology for production of shale oil, a type of synthetic crude oil. The process used a vertical retort where heating causes decomposition of oil shale into shale oil, oil shale gas and spent residue. The particularity of this process is that oil shale in the retort moves from the bottom upward to the top, countercurrent to the descending hot gases, by a mechanism known as a rock pump. The process technology was invented by the American oil company Unocal Corporation in late 1940s and was developed through several decades. The largest oil shale retort ever built was the Union B type retort.
History
Union Oil Company of California (Unocal) started its oil shale activities in 1920s. In 1921, it acquired an oil shale tract in the Parachute Creek area of Colorado, southern Piceance Basin. The development of the Union process began in the late 1940s, when the Union A retort was designed. This technology was tested between 1954 and 1958 at the company-owned tract in the Parachute Creek. During these tests, up to 1,200 tonne per day of oil shale was processed, resulting of 800 barrels per day (130 m3/d) shale oil, which was refined at a Colorado refinery. More than 13,000 barrels (2,100 m3) of gasoline and fuels were produced. This production was finally shut down in 1961 due to cost.