Experiments on permeability evolution with temperature of oil shale

In this paper we use a permeability measuring system developed by Taiyuan University of Technology measure the permeability of oil shale to temperatures in the range 200 to 500°C. Two samples have been tested in this system with N₂ as permeant. The samples are from the Daqing (northeastern China) and Changqing (western China) oil shale deposits. The experiments show that temperature has a significant impact on the permeability of oil shale. With different initial permeability of these two samples, temperature thresholds are shown to be important in the evolution of the permeability. For one sample, permeability first increases and then decreases to a minimum at 400°C (Daqing). For the second sample, the permeability decreases to a minimum at 450°C and then increases significantly after this threshold (Changqing). We conclude from these observations that the transport properties of shale are influenced by the complex interaction of mechanical and chemical processes activated at elevated temperatures.