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akadeemia kirjastus
SINCE 1984
Oil Shale cover
Oil Shale
ISSN 1736-7492 (Electronic)
ISSN 0208-189X (Print)
Impact Factor (2021): 1.442
Evolution of pore characteristics in oil shale during pyrolysis under convection and conduction heating modes; pp. 224–241
PDF | 10.3176/oil.2020.3.04

Lei Wang, Dong Yang, Yangsheng Zhao, Guojing Wang

The pores in oil shale, which act as channels for the migration of products of cracking of organic matter and the place for heat transfer in the rock mass, directly influence pyrolysis efficiency. In this paper, the pore characteristics of oil shale during pyrolysis under the convection and conduction modes of heating were determined by mercury intrusion porosimetry (MIP). Results show that in case of both the heating modes, the threshold temperatures for transformation of pore structure from simple to complex are 382 °C and 452 °C, respectively. The porosity of oil shale subjected to convection heating is generally higher than that subjected to conduction heating. By the convection heating mode, the high-temperature fluid can extract the shale oil attached to the pore wall and increase the porosity. As the pyrolysis temperature increases from 314 °C to 555 °C, the average pore size of oil shale increases from 23.70 to 218.15 nm in convection heating and from 21.68 to 145.60 nm in conduction heating. During the pyrolysis of organic matter and extraction of oil and gas, high-temperature steam continuously widens the pores. Finally, when the pyrolysis temperature is above 314 °C, pores with a smaller size gradually change into mesopores and macropores with a larger size. It is proved that under the convection heating mode, oil shale changes from a dense rock to a porous medium with an obviously higher amount of pores.


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