Dr. Lee and his research group have been studying oil shale extraction and utilization of shale oil since 1980. His team's research foci and highlights are described below.
(1) Determination of the kinetics of oil shale pyrolysis for a variety of world-wide shale deposits, including U.S. Eastern Devonian shale, Colorado Green River Formation shale, North Carolina shale, Chattanooga shale, Australian Stuart shale, and Jordanian shale.
(2) Development of efficient oil shale extraction processes whose yields substantially exceed the Fischer Assay values of oil shale. These efforts generated both subcritical CO2 retorting process and supercritical CO2 extraction process.
The first technology takes advantage of the material property changes of kerogen [oil shale hydrocarbons] and its pyrolytic intermediates in high-temperature but subcritical CO2 (i.e., low pressure), which are swelling of kerogen and subsequent changes in viscosity and mobility. The enhanced extraction efficiency of the first technology was remarkably high for certain types of oil shales including Colorado shale and North Carolina shale. Lee's team received a U.S. patent for this process:
- S. Lee and R. Joshi, "Enhanced Oil Recovery from Western United States Type Oil Shale Using Carbon Dioxide Retorting Technique," U.S. Patent No. 4,502,942, March 5, 1985.
The latter technology exploits the superior extractive properties of supercritical CO2 toward straight chain hydrocarbons. This process treatment established that the Fischer Assay procedure for an oil shale can be exceeded by an advanced extraction process by a substantial margin by as much as 50-60% and all future process development should target a much higher oil yield than the Fischer Assay of the shale.
S. Kesavan, A. Ghosh, V. Parameswaran, and S. Lee, "Supercritical Extraction of Stuart Shale," Fuel Sci. & Tech. Int'l., 6(5), pp. 505-523, 1988.
Both processes utilizing carbon dioxide (CO2) have additional outstanding merit of suppressing dolomite decomposition, which is a parallel endothermic reaction accompanying the principal oil shale pyrolysis reaction in most thermal extraction processes. Calcination and half-calcination of dolomite generates carbon dioxide. Considering the modern era's greenhouse gas concerns and control efforts, its process implication is of high significance.
(3) Characterization of shale oil depending upon the oil shale's geological origin as well as the specific extraction processes applied. Detailed GC/MS analysis of a large number of shale oil samples elucidated the molecular compositions/structures of shale oil crude and their dependence on the geological origin and extraction procedures.
M. E. Polasky, S. K. Kesavan, and S. Lee, "Chemical Compositions of Shale Oil. I. Dependence on Oil Shale Origin," Fuel Sci. & Tech. Int'l., Vol. 9, No. 8, pp. 1015-1059, 1991.
S. Lee, K. L. Fullerton and M. E. Polasky, "Chemical Composition of Shale Oil. II. Dependence on Extraction Process," Fuel Sci. & Tech. Int'l., Vol. 9, No. 9, pp. 1151-1179, 1991.
(4) More recent efforts and interest areas include [a] devising a new extraction process that is based on hot carbon dioxide gas injection extraction, which takes advantage of the aforementioned process and environmental benefits, [b] developing a lower temperature in-situ process, [c] co-processing of oil shale with other resources, and [d] catalytic upgrading of shale oil.
An extensive overview of oil shale science and technology is summarized in his authored book (1991).
S. Lee, Author, "Oil Shale Technology," CRC Press, Boca Raton, FL, ISBN-0-8493-4615-0, 1991
This book is currently being updated for a 2nd edition by Dr. Lee, which will include recent advances made in shale gas and shale oil.
Dr. Lee's research group at Ohio University is currently conducting research in the following areas of shale gas technology as near-term solutions:
- New environmentally friendly fracking technology
- New chemicals for fracking fluids; environmentally benign and/or cost effective
- Soil and water decontamination and remediation
A next-generation shale oil and shale gas technology is currently being developed with a financial sponsorship by Samwha Solutions, Inc.
- Novel Frac-less Technology that does not require frac water and frac sand, but yields high efficiency.
For shale gas utilization and conversion to other chemicals, Dr. Lee's authored book is a good resource.
- S. Lee, Methane and Its Derivatives, Marcel Dekker, New York, NY, 1997