Circular 87—Preliminary investigations of the oil shale potential in New Mexico

By R. W. Foster, P. B. Luce, L. G. Culver, and B. B. Maras, 1966, 22 pp., 4 tables, 3 figs.

More than 4,800 qualitative and quantitative tests were conducted on New Mexico shales to determine the presence of commercial deposits of oil shale. To date, this testing has not revealed any extensive deposits of this type. Testing was restricted to gray and black shales that occur in quantity only in rocks of Devonian, Pennsylvanian, Cretaceous, and Tertiary ages. Low-yield deposits of oil shale were found in Pennsylvanian shales, particularly near Abo Pass; in the Cretaceous Mancos Shale at Carthage and in the northwestern part of the San Juan Basin; in the Cretaceous Graneros Shale near Springer; and in the Tertiary Raton Formation near Raton. Additional testing of these intervals and of the gray to black shales exposed in southwestern New Mexico is needed to complete an oil shale evaluation of the state.
Oil shale is a fine-grained sedimentary rock that will yield a petroleum-like substance by destructive distillation. Other bituminous rocks that contain soluble hydrocarbons and that yield oil by heating, such as asphaltic sandstones and bituminous limestones, are not included in this report, as well as shales containing crude oil that may be extracted by conventional drilling and production methods.

The organic matter in oil shale generally is referred to as kerogen and consists mostly of aquatic plant algae of high-molecular weight hydrocarbons containing nitrogen, oxygen, and sulfur. Upon heating, the organic matter in the shale converts to a soluble bitumen over a wide range of temperatures beginning at about 200ºC. Vapors emitted at approximately 350ºC condense to form a highly viscous liquid that may be refined to produce gasoline, kerosene, fuel oil, asphalt, waxes, and other petroleum products.

Oil shales range from black to brown and yellow, plus various shades of gray. They may be massive, with a conchoidal fracture, or they may consist of fissile, "paper" shales. Some have a waxy luster; others are dull and stony in appearance. Some oil shales are not true shales but consist largely of calcium and magnesium carbonates. Some oil shales are intimately associated with coal beds, such as those in Spain, Scotland, France, and Australia; others, such as those in the U.S., Estonia, and Sweden, are not. Beds of oil shale occur in rocks representing almost all of the geologic ages. Deposits in Sweden are Cambrian or Silurian in age; some beds in Canada are Devonian; in Brazil, Permian; Austria, Triassic; Germany, Jurassic; Israel, Cretaceous; and the U.S., Tertiary.