Pyrolytic behaviour of Spanish oil shales and their kerogens

A comparative study of the thermal behaviour of selected Spanish oil and th eir kerogen concentrates has been carried out. The oil shales differ in geo logical age, depositional environment, source location and degree of maturi ty. The influence of the amount and composition of mineral matter in the th ermal behaviour of the oil shales and its influence on the amount of hydroc arbons released has been assessed. In mineral matter-rich samples, the mine ral matter is responsible for a delay in the hydrocarbon generation during thermal heating and also retains part of the generated hydrocarbons, which might lead to erroneous kerogen typing when using thermal methods. The most immature samples are characterised by relatively higher proportion of oxyg en-bearing functional groups which are more labile bonded to the kerogen an d are released at lower temperatures during pyrolysis. Temperatures of init iation of kerogen cracking have shown to be more sensitive to reflect the m aturity than temperatures of maximum rate of hydrocarbons release under the low heating rates used in this study. The most aliphatic and oxygen-rich k erogen have shown to yield the highest conversion to shale oil whereas the initially most aromatic kerogens are more prone to condense yielding higher coke amounts. (C) 2000 Elsevier Science B.V. All rights reserved.