The term oil shale generally refers to any sedimentary rock that contains solid bituminous materials that are released as petroleum-like liquids when the rock is heated.
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Izraz naftni škriljevci općenito se odnosi na bilo koju sedimentnu stijenu koja sadrži čvrste bitumenske materijale koji se oslobađaju kao tekućine slične nafti kada se stijena zagrijava.
To obtain oil from oil shale, the shale must be heated and resultant liquid must be captured. This process is called retorting, and the vessel in which retorting takes place is known as a retort. The largest known oil shale deposits in the world are in the Green River Formation, which covers portions of Colorado, Utah, and Wyoming. Estimates of the oil resource in place within the Green River Formation range from 1.5 to 1.8 trillion barrels. Not all resources in place are recoverable. For potentially recoverable oil shale resources, we roughly derive an upper bound of 1.1 trillion barrels of oil and a lower bound of about 500 billion barrels.
Since the early 1980s, oil shale has not been on the U.S. energy policy agenda, and very little attention has been directed at technology or energy market developments that might change the commercial prospects for oil shale.
Da bi se dobila nafta iz naftnih škriljevaca, škriljevci se moraju zagrijati i uhvatiti rezultirajuća tekućina. Taj se proces naziva retorting, a posuda u kojoj se odvija retorta. Najveća poznata nalazišta naftnih škriljevaca na svijetu nalaze se u formaciji područja Zelene rijeke, koje pokriva dijelove Colorada, Utaha i Wyominga. Procjene količine nafte formacije Zelene rijeke iznose između 1500 i 1800 milijardi barela. Ne mogu se svi resursi iskoristiti. Za potencijalno iskoristive resurse naftnih škriljevaca, otprilike dobivamo gornju granicu od 1100 milijardi barela nafte i donju granicu od oko 500 milijardi barela.
Od početka 1980-ih naftni škriljevci nisu na dnevnom redu američke energetske politike, a vrlo malo pozornosti usmjereno je na tehnološka ili energetska kretanja na tržištu koja bi mogla promijeniti komercijalne izglede za naftne škriljevce.