In this study, a self-designed test system for injecting water vapour was used to pyrolyse oil shale from Barkol, Xinjiang, China. The internal structure of oil shale samples after water vapour pyrolysis at different temperatures was characterised using micro-computed tomography (micro CT). The results showed that under the action of high-temperature water vapour, oil shale underwent evident thermal cracking and pyrolysis, and the porosity increased from 0.08 of the original state to 16.73 at 550 degrees C. At 300 degrees C, the maximum pore group was distributed along the bedding plane due to the influence of thermal cracking, and the equivalent diameter was 1201.73 mu m. When the water vapour temperature increased from 300 degrees C to 400 degrees C, the organic matter at a low boiling point in oil shale began to pyrolyse, forming several pores. These pores were gradually connected with adjacent fractures. The pores with an equivalent diameter of approximately100-500 mu m in oil shale accounted for > 60 of the total pore volume. The maximum pore cluster expanded perpendicular to the bedding plane, but there was still no effective seepage channel. With an increase in the water vapour temperature, the largescale pyrolysis of organic matter began and the pores and fractures in oil shale were continuously generated and gradually connected; at 450 degrees C, the seepage channel connecting the entire digital core area began to form. At 550 degrees C, the equivalent diameter of the maximum pore group reached 5756.72 mu m, accounting for 69.65 of the total pore volume.
展开▼
