Oil Shale Development: Status and Prospects
Authors: Whitcombe J.A. 
Published: December 2007

Technology is available for commercial development of the vast U.S. oil shale deposits. However, economic changes and uncertainties, including inflation in construction costs, impede this development. If economic incentives are provided for construction of pioneer oil shale plants, oil shale production could reach 2 million BID in 1995.

Introduction

This paper concerns oil shale, specifically the status of oil shale development and the contribution that oil shale can be expected to make to the nation's energy supply during the next 20 years. The subject is timely because the United States needs oil, and the oil shale deposits of the U.S. constitute the world's largest known hydrocarbon reserve.

Oil Shale Reserves

The prime oil shale deposits of the U.S. are in northwestern Colorado, eastern Utah, and southern Wyoming. The largest deposit in this region is in a 1,200-sq mile area of northwestern Colorado referred to as the Piceance Basin. Piceance Basin. The oil shale deposit of the Piceance Basin has been extensively explored and the results in terms of potential oil in place are staggering. The 1,200-sq mile area potential oil in place are staggering. The 1,200-sq mile area is underlain by a rich oil-shale bed referred to as the Mahogany Zone. The bed is from 75 to 250 ft thick, and the in-place oil content is projected to be 164 billion bbl. Below the Mahogany Zone and separated by lowergrade materials are two other rich zones. The total content of the three rich zones is 320 billion bbl.

In the three-state area, and counting shale in leaner beds, the total estimated in-place resource is 1.8 trillion bbl. For this discussion, it is not important what specific reserve estimate is considered, for it is clear that the reserves are more than enough to make a vast contribution to the nation's energy supply. For example, the Mahogany Zone in-place reserve of the Piceance Basin is many times larger than the proven Piceance Basin is many times larger than the proven conventional petroleum reserves of the U.S.; and the reserves of the three rich zones of the Piceance Basin approach in magnitude the proven reserves of all the Middle East.

Oil Shale Recovery Processes

All work on oil shale recovery has focused on heating the shale to recover the contained oil and gas, for there is no other practical method for extracting a significant portion of the contained oil. In the processes studied, portion of the contained oil. In the processes studied, the shale is heated to about 900 degrees F, at which temperature the organic material in shale rapidly decomposes into oil vapor and gas. Cooling this vapor stream produces liquid oil and uncondensed, light hydrocarbon produces liquid oil and uncondensed, light hydrocarbon gases.

Surface Retorting Processes

Most development work on oil shale recovery has been directed to mining the shale, bringing it to the surface, and then processing it in surface facilities. The various surface retorting processes can be classified according to the method used to provide heat for the retorting reaction.

With one procedure, the gas combustion process, the source of heat is internal combustion within the retorting vessel, and a controlled amount of air is admitted to the retort to supply oxygen for the combustion reaction.

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