Unocal Corporation
Unocal Corporation started the development of the Union process 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. This production was finally shut down in 1961 due to cost. In 1957 Texaco built a shale oil extraction pilot plant to develop its own hydroretorting process. In the early 1960s TOSCO (The Oil Shale Corporation) opened an underground mine and built an experimental plant near Parachute, Colorado. It was closed in 1972 because the price of production exceeded the cost of imported crude oil.