Concurrent Gasification and Retorting of Oil Shale - A Dual Energy Source
Authors: Burwell E.L. , Jacobson I.A. 
Published: December 2007

American Institute of Mining, Metallurgical, and Petroleum Engineers, Inc.
This paper was prepared for the Rocky Mountain Regional Meeting of the Society of Petroleum Engineers of AIME, to be held in Denver, Colo., April 7–9, 1975. Permission to copy is restricted to an abstract of not more than 300 words. Illustrations may not be copied. The abstract should contain conspicuous acknowledgment of where and by whom the paper is presented. Publication elsewhere after publication in the JOURNAL paper is presented. Publication elsewhere after publication in the JOURNAL OF PETROLEUM TECHNOLOGY or the SOCIETY OF PETROLEUM ENGINEERS JOURNAL is usually granted upon request to the Editor of the appropriate journal provided agreement to give proper credit is made. provided agreement to give proper credit is made. Discussion of this paper is invited. Three copies of any discussion should be sent to the Society of Petroleum Engineers office. Such discussion may be presented at the above meeting and, with the paper, may be considered for publication in one of the two SPE magazines.

Abstract
The effects of pressure, oil shale grade, oxygen enrichment, and steam injection on the quantity and heating value of offgas from oil shale retorting was studied in the laboratory. Equations were developed which show that large quantities of medium Btu gas can be produced in conjunction with shale oil production. Results also indicate that up to 84 percent of the original organic content can be produced as combustible gases and crude shale oil. Btu distribution in the gas-liquid product mixture is up to 1 to 1.

Introduction
Government and industry oil shale research groups have been working both independently and cooperatively to develop economically feasible and ecologically satisfactory energy recovery processes. One problem that has attracted much processes. One problem that has attracted much attention has been that of increasing process efficiency to insure maximum utilization of the resource.
Many processes under investigation involve burning a portion of the oil shale to produce sufficient heat to retort the remainder. During all of these processes some of the original organic material is converted to gases. The low Btu level of gases normally produced, collection and handling costs, and other problems have combined to prevent any widespread usage of these offgases. The object of this study by personnel of the Laramie Energy Research Center was to determine levels of operating variables such that the heating value of the offgases could be maximized.
A small retort was assembled and instrumented, and two series of experiments were completed to investigate the effects of pressure, oil shale grade, oxygen enrichment, and steam injection on the quantity and heating value of gas produced during forward combustion of oil shale. Data collected were tabulated for computer analysis and regression equations were developed which satisfactorily describe the system.
The volume of offgas that would be produced during a commercial-sized application of the in situ recovery process to oil shale is predicted to be in excess of 1 billion cubic feet per day. Because of the tremendous volume of gas involved, there would be obvious economic advantages to operating in a manner to produce a usable offgas.

EXPERIMENTAL DESIGN
Application of this process sets inherent limitations on the number of variables that can be controlled and also restricts some to narrow limits.