摘要
Oil shales are one of those naturally occurring resources that require so much costly treatment to convert them into useful products that they are only worked on a large scale at times when the availability of cheaper alternatives is restricted. The need to find secure UK supplies during the First World War led to attempts to exploit the potential oil reserves contained in the more organic-rich parts of the Jurassic Kimmeridge Clay Formation. The most costly of these was that carried out in west Norfolk by the privately funded English Oilfields Ltd. (EOL) in 1916-1921 under the direction of Dr. William Forbes-Leslie M.D., FGS. Extensive treatment works were constructed on the Kimmeridge Clay outcrop at Setchey, five miles south of King's Lynn, but very little oil shale was worked or retorted. An extensive drilling programme claimed to have proved sulphur-free oil shales, hundreds of millions of tons of free oil, a 21-m thick seam of natural paraffin wax (ozokerite), and an abundance of metalliferous minerals. At its peak in 1920, the stock-market value of the company was several hundred million pounds at present-day prices. The turning point came in 1921 when samples of shale oil from Setchey and the products derived from them by distillation were shown to have no commercial value because of their high sulphur contents. There was, at that time, no commercially viable method of reducing the sulphur contents to an acceptable level. The free oil, ozokerite and metalliferous minerals only existed in the reports to the shareholders.