Oil shales and their analysis

Oil shales are defined as fine grained sedimentary rocks containing abundant mainly sapropelic organic matter which produce oil on distillation (the merits of their classification are discussed). They represent a vast, relatively untapped, potential source of energy. Oil shales are of wide geographic occurrence and are often represented by very large scale deposits, providing many opportunities for commercial exploitation (previous exploitation history is documented briefly, and resource potential of major shale areas discussed). To exploit this significant resource analytical support is necessary in all three stages, i.e., exploration, appraisal, and exploitation/production of a shale project. Product shale oil analysis provides information to assist in refinery design, allows feedstock quality assessment and provides for environmental hazard monitoring; many techniques are available for this but exact requirements and circumstances dictate the choice of method. Physical property assessment, microscopy and borehole specific gravity logging have been used in the field. Traditional laboratory analysis has relied on carbonization assay; Fischer Assay being the standard method. Indirect thermal methods, e.g. pyrolysis FID, thermal chromatography, laser pyrolysis and TGA/DTA have also been used to provide meaningful oil yield data. More recently, n.m.r., FT-i.r. and EPR techniques have been investigated. All methods for yield assessment, except carbonization assay, require careful calibration for their success and these methods and their application are discussed in detail. Shale oil analysis originally employed classical wet chemical analytical techniques but now relies almost exclusively on Chromatographic separation. Several analytical schemes are presented which provide compound class analysis, specific compound identification, and environmental hazard monitoring utilizing capillary column g.c., HPLC and g.c.—m.s. techniques. The use of shale oil and retort volatiles analysis in the assessment of retorting efficiency is reviewed and its application in process control and monitoring discussed.