OIL SHALE DEVELOPMENT

• Shale Oil - A Competitive Fuel In the 1960's

TElL ERTL' CAMERON & JONES, INC. MEMBER AIME DENVER, COLO. Downloaded from http://onepetro.org/JPT/article-pdf/13/10/983/2213551/spe-69-pa.pdf by guest on 01 October 2021

tion yields three products: (1) a high-carbon residue which remains with the rock; (2) a non condensable gas that is chiefly hydrogen and methane; and (3) a condensable gas that is condensed to shale oil. The shale oil recovery may represent up to 70 per cent of the fuel value of the origi­ nal organic matter (Fig. 3). Oil shales of commercial interest yield 5 to 15 weight per cent shale oil. Shale oil may be considered a protein or carbohydrate, in contrast to petroleum which is a hydrocarbon. The molecules of shale oil are thought to contain not only carbon and hydrogen, but also oxygen, nitrogen and sulfur. A high percentage of the molecules are unsaturated. The organic matter in the oil shale or the shale oil, itself, often is referred to as kerogen (which means wax-forming) be­ cause much wax can be crystallized from shale oils.

Oil Shale Resources Some of the oil-shale deposits, such as the Chattanooga black shales of the United States and the Irati oil shale of southern Brazil, underlie more than 100,000 sq miles of area. Others, like the Swedish K varntorp deposit, the Spanish Puertollano deposit and the German Messel deposit, occur in basins only a few square miles in area. The important deposits of the world, in which enough exploration has been done to designate reserves of oil

Original manuscript received in Society of Petroleum Engineers office Fi~. I-Dr. Joaquim Maia, Superintendente Fundacao Gor­ April 5, 1961. Revised manuscript received Aug. 3, 1961. selX (an organization to encourage mining and metallurgi­ ';' The author is currently located in Rio de Janeiro, Brazil. where he is in charge of work Cameron and Jones, Inc., is performing in con­ cal education) of Ouro Preto, Brazil, examines a piece of junction with Petrobras. the national Brazilian oil company. Irati oil shale taken from the large pile in the hackground.

OCTonER, 1961 SPE 69 983 shale, are the Green River deposits of Colorado, Utah in the U. S. The present Scottish shale-oil extraction plants and Wyoming in the U. S., and the Irati deposit in the are basically those invented, built and used before the turn states of Sao Paulo, Parana, Santa Catarina and Rio Grande of the century, except as their throughput and efficiency do SuI in Brazil. The Green River deposit in Colorado have been raised considerably by skilled engineering. The has been shown by the U. S. Geological Survey to have Spanish, who decided to build their oil-shale plant during a reserve of more than 1,000 billion bbl of shale oil in World War II for reasons of speed and availability of an area of about 1,000 sq miles. The reserves in designs and material, erected a Scottish-type retorting plant Utah and Wyoming have not been extensively explored. and are operating it well. The French, who experimented Although the Irati deposit has been mapped along 1,000 with many types of retorts, have abandoned them all­ miles of outcrop, it has been explored by detailed drilling due in large part to the cost of mining their thin, deep only in an area near the town of Sao Mateus do SuI in oil-shale deposits. Because of great depths and difficult southern Parana. There, an area of 35 sq miles has a mining conditions, the cost of mining in Scotland is about recoverable reserve of 600 million bbl. All present evi­ $4.50/ton, or about $8.00/bbl of liquid recovered. Still dence indicates that further exploration of the Irati forma­ the Scottish industry continues, though at a diminishing tion will increase the reserve to many billions, if not rate. hundreds of billions, of barrels. Therefore, both the Green Most of Spain's lubricating oil and candle wax is manu­ River and Irati oil shales will be sources of liquid fuels at factured from shale oil, and a modern industrial complex least as important as the major petroleum-producing areas is based on the production of 3,000 tons/day of oil shale. of the world. In Sweden, low-cost mining, skillful retort development work and thorough utilization of the low-grade oil shale Downloaded from http://onepetro.org/JPT/article-pdf/13/10/983/2213551/spe-69-pa.pdf by guest on 01 October 2021 Industrial DeVelopment have resulted in the commercial production of sulfur. chemicals and lime in addition to oil. In Germany, two The writer has seen the oil-shale plants in Sweden, private plants use oil shale profitably, although one uses Spain, Scotland and Germilny that are operating now­ it chiefly as a source material for cement (including thc also those in France, Germany and Scotland which have contained heat value), and the other as a source of liquid been abandoned. He has also been associated closely with fuels and also as a raw material for artificial building the work done in the U. S. by the U. S. Bureau of Mines stone. The Dotternhausen plant fluidizes the oil shale; the and the Union Oil Co. of California, and with the work Messel plant uses a retorting plant built before the turn being done in Brazil by Petrobras, the Brazilian national of the century. oil company. China and Russia both have active oil-shale industries. Some of the European developments date from the The Chinese industry is reported to be yielding oil at a middle of the 19th century, during which time oil-shale rate of 40,000 B/D, and a tenfold increase is contemplat­ plants existed not only in Scotland and France, but also ed. The gas supply for the city of Leningrad is reported to be supplied from Estonian oil shale.

Production Techniques The production of shale oil has been chiefly a matter of mining the rock, then distilling the organic matter in a retort. Sweden obtains shale oil both from retorts and from an in situ method. Several American oil companies have experimented with in situ retorting with unan­ nounced results. Mining Where the deposits are close to the surface as in Kvarntorp, Sweden, Dotternhausen, Germany, or southern Brazil, modern surface mining techniques can be used.

Fig, 2-Coronel Martin's Mine, a small mine in the Irati oil-shale formation at Sao Mateus do SuI in the Brazilian Fig. 3-This 30-lh pile of rich oil shale yields ,tate of Parana, shows the flat-bedded nature of oil shale. about Yl-gal of oil.

JOURNAL OF PETROLEUM TECHNOLOGY These include stripping the overburden with draglines or the vessel which is a section of a circular cone. The top of bucket-wheel excavators, and drilling and shooting the the vessel is open and the spent shale spills over the top. exposed oil shale to loosen it' so that it can be loaded Air is drawn into the top of the retort. The oxygen of the by large shovels either into trucks or onto conveyor belts air unites with the high-carbon residue of the retorted oil for transportation to the retorting plant. shale to heat the products of combustion well above the Where the deposit is hundreds of feet underground, as temperature of decomposition of the organic matter in the in western Colorado, the oil shale cannot be mined eco­ oil shale. As the hot gases are drawn downward they nomically by surface methods. Colorado oil shale is how­ cool as they heat the upcoming oil shale, at the same time ever, a strong rock in which large unsupported op~nings mixing with the noncondensable and condensable gases can be excavated safely. The openings are so large (Fig. that are emitted or expelled by the decomposing organic 4) that automatic drilling equipment can be used, the matter. The mixed gases continue downward in the retort blasting operations can be mechanized, and the broken contacting the upcoming cold oil shale, are cooled and the oil shale can be loaded and transported by the same ef­ condensable portions of the gas condense to shale oil. ficient means used by surface mines. Because no over­ The shale oil gathers in the bottom of the retort and is burden must be removed, the cost of mining oil shale withdrawn continuously. The cold incoming oil shale from underground in the Piceanoe Creek basin is of the passes through shale oil, and the cold outgoing products same order of magnitude as mining from the surface at of combustion mixed with the non condensable shale gas modern, low-cost mines. are drawn through the seal of shale oil. The Union retort, in one vessel, produces spent shale, shale oil and a com­ Retorting bustible mixed gas from oil shale. The spent shale is dis­ The oil shale is crushed and screened before being fed carded, the shale oil is sent to a refinery and the com­ Downloaded from http://onepetro.org/JPT/article-pdf/13/10/983/2213551/spe-69-pa.pdf by guest on 01 October 2021 into the retorts. Most retorts use fist-size or larger pieces bustible gas is used as a source of heat and power. of oil shale. The tY.Je of retorts used in Western Europe process from 1 to 20 tons/day. They are externally heat­ In the gas combustion retort the oil shale is fed into the ed, a method that limits the size of the retort and one top, and retorted oil shale with part of the carbon burned which results in uneven heating of the oil shale. The work from it is drawn out of the bottom. Recycle gas is fed into in the U. S. and Brazil is aimed at the development of the bottom to recover heat from the retorted oil shaie, large-capacity retorts to serve large-capacity plants. The and a mixture of recycle gas and air is fed into the center Bureau of Mines developmental retort treated 250 tons/ of the retort where part of the gas and part of the high­ day, the Union Oil Co. of California retort treated 1,200 carbon residue on the retorted oil shale is burned to raise tons/day and Brazil is beginning a prototype program to the temperature of the gas to that necessary to decompose process 2,500 tons/day in one retort. The three retorts the organic matter of the oil shale. The oil-shale gases are are heated internally, thereby permitting the vessels to mixed with the products of combustion, and the com­ be of any size. bined gases are drawn up through the cold incoming oil shale. The gases are cooled to temperatures below the con­ In the Union Oil Co. of California retort (Fig. 5), the densing temperature of the shale-oil vapor. The shale oil, oil shale is fed from the bottom and is pumped through

Fig. 4-0il·shale mining in western Colorado uses large Fig. 5-Vnion Oil Co. of California's oil·shale retort mohile equipment to attain low costs. treated 1,200 tons/day.

OCTOBER, 1961 985 instead of condensing into drops, condenses as a mist Economics that remains in suspension in the gases and is drawn out The technologies of mining and processing oil shale are of the retort for recovery in a cyclone or electrostatic now well understood. The size and unformity of the large precipitator. deposits permit highly mechanized, low-cost methods of The engineers of Petrobras have developed yet another mining. Thorough mining development work in both the process, one which fits the Brazilian oil shale and economy U. S. and Brazil shows that the oil shales can be delivered better than the internal combustion processes developed crushed to the retorts for about $.50/ton. Retorting in by Union and the Bureau of Mines. The process is de­ large vessels can be automatically controlled so that the signed to recover not only oil, but also the undiluted shale operating cost as well as the capital cost is low. Up-to-date gas, which contains more than 25 per cent hydrogen sulfide estimates for the cost of producing shale oil in western and from which large quantities of sulfur and liquefied Colorado from Mahogany Ledge oil shale are about $1.00/ petroleum gases can be obtained. Both of these products bbl. Dr. Hilnor Cangucu, superintendent of the Petrobras presently must be imported, so their recovery is particular­ Oil Shale Div., recently reported to the board of directors ly valuable to the Brazilian economy. This Petrosix process of Petrobras that shale oil can be produced from the uses a vertical retort that is fed from the top. Part of the Irati formation, after taking credits for liquified petroleum shale gas produced is heated to retorting temperature and gas and sulfur as by-products, for a cost equivalent of fed into the center of the retort, while part is injected $1.03/bbl. into the bottom of the retort to recover heat from the re­ Since the U. S. is flooded by a glut of petroleum, oil­ torted oil shale. The two streams of shale gas heat the shale development is held in abeyance. Brazil, on the incoming cold oil shale to retorting temperature, combine other hand, imports 170,000 B/D of petroleum at a cost Downloaded from http://onepetro.org/JPT/article-pdf/13/10/983/2213551/spe-69-pa.pdf by guest on 01 October 2021 with the expelled condensable and noncondensable shale which seriously drains Brazil's foreign exchange. There­ gases, and are withdrawn through the cool incoming oil fore, Brazil probably will be the first nation in the world shale. The condensable fraction condenses as a mist and to have a truly modern industry built to produce liquid is withdrawn with the gas to be recovered as shale oil. Part fuels from oil shale. of the gas is recycled to continue the retorting, whereas the remainder is taken to the sulfur and LPG recovery Summary and Conclusions plants. The treated gas (after sulfur and LPG removal) Oil shale can be a competitive source of liquid fuels has a high heating value, can be used for heat and power, presently in both the U. S. and Brazil, and undoubtedly or can be sold for distribution to the cities of Brazil. The will be such a source before the Sixties pass into history. retorted oil shale from the process contains about 7 per Important students of oil economics tend to overlook cent high-carbon residue. Studies are underway to develop the imminent importance of oil shale. This can be il­ methods of using the high-carbon residue as a source of lustrated by a remark made by Hill' in a recent article in heat and power. which he stated, "and when U. S. production reaches its peak around 1970 and begins its inevitable decline, all the Refining increase in consumption must come from imports". The The Colorado shale oil is a 20° to 21 ° API gravity oil statement would be more accurate if he had said "all with a pour point of 90°F. It contains nearly 2 per cent the increase in consumption must come from oil shale", nitrogen and 0.7 per cent sulfur. The methods proposed because the evidence keeps piling up that by 1970 liquid for refining include the hydrogenation of all or part of the fuels from oil shale will be less expensive than petroleum, oil under moderate pressure and in the presence of a both from the standpoint of capital expenditure per barrel catalyst. The resulting products are straight-chain light day and the cost of production. *** paraffins that can be fractionated to top-quality jet and 'Hill, K. E.: "Probable Pattern of United States Petroleum Supply", diesel fuels. The hydrogen removes the nitrogen as am­ Jour. Pet. Tech. (Nov., 1960) XII. No. 11, 15. monia and the sulfur as hydrogen sulfide, both of which TELL ERTL is vice-president of Cam­ become valuable by-products that help pay the cost of eron & Jones, Inc., Denver, and presi­ refining. In Feb., 1961, 20,000 bbl of Colorado shale oil dent of Energy Resources Technology were refined in the Gilsonite refinery of the American Land, Inc., also in Denver. Currently Gilsonite Co., with high throughput rates and a good located in Rio de Janeiro, Brazil, he yield of gasoline. heads work being performed by Cam­ The Brazilian shale oil is of a better quality than Colo­ eron & Jones in conjunction with Pet­ rado shale oil, with an API gravity of 25° and a pour robras, the national Brazilian oil com­ point of 35°F, a nitrogen content of only 0.6 per cent pany. He received a BS degree from the and sulfur of 1.7 per cent. Though detailed refining studies U. of Washington, and MS and PhD have not yet been made on Irati shale oil, it has been degrees from Columbia U. From 1950 said that the shale oil can be refined to useful gasolines until 1955 he served as chairman of the Mining and Petrol­ and diesel fuels in conventional refineries. eum Engineering Dept. at The Ohio State U.

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