While oil shale is heated to a certain temperature, its porous structure undergoes continuous modification and as a result, the rock permeability will also change with increasing temperature. In this paper, the mercury injection apparatus was used for measuring the pore size of oil shale samples at different temperatures. The results showed that, firstly, as the temperature increased, the total pore volume, average pore size and porosity of oil shale increased significantly. When the temperature reached 600 °C, the porosity was increased to 34.6%, making 8.3 times the initial porosity. Secondly, during the heating of oil shale, the volume of mesopores (0.1 μm < d ≤ 1 μm) increased continuously while that of micropores (d ≤ 0.015 μm) decreased. Because the solid organic matter in oil shale was subjected to pyrolysis, micropores began to merge to become medium-sized or mesopores, or even macropores. In the temperature range of 400–500 °C, organic matter was pyrolyzed heavily and both the increment of medium-sized pores percentage and the decline of micropores percentage were very significant. Thirdly, the oil shale permeability increased with rising temperature, being at 600 °C 3.0 × 10–8 m2, which is nearly 600 times that at the room temperature stage of pyrolysis. Shortly, heating oil shale to high temperature can generate new pores and merge the existing ones, which will prompt transforming the tight oil shale into porous rock with high permeability and favour oil and gas seepage.
1. Dyni, J. R. Geology and resources of some world oil-shale deposits. Oil Shale, 2003, 20(3), 193–252.
2. Li, S. Y., Ma, Y., Qian, J. L. Global oil shale research, development and utilization today and an overview of three oil shale symposiums in 2011. Sino-Global Energy, 2012, 17(2), 8–17 (in Chinese).
3. Jiang, X. M., Han, X, X., Cui, Z. G. Study of comprehensive utilization technology of oil shale. Progress in Nature Science, 2005, 15(11), 1342–1345 (in Chinese).
4. Qian, J. L., Wang, J. Q., Li, S. Y. World oil shale utilization and its future. Journal of Jilin University (Earth Science Edition), 2006, 36(6), 877–887 (in Chinese).
5. Yang, D., Zhao, J., Kang, Z. Q., Zhao, Y. Technology and numerical analysis of in-situ electrical heating on oil shale. Journal of Liaoning Technical University (Natural Science). 2010, 29(3), 365–368 (in Chinese).
6. Han, X. X., Jiang, X. M., Cui, Z. G. Change of pore structure of oil shale particles during combustion. Part 2. Pore structure of oil-shale ash. Energ. Fuel., 2008, 22(2), 972–975.
http://dx.doi.org/10.1021/ef700645x
7. Kang, Z. Q., Yang, D., Zhao, Y. S., Hu, Y. Q. Thermal cracking and corresponding permeability of Fushun oil shale. Oil Shale, 2011, 28(2), 273–283.
http://dx.doi.org/10.3176/oil.2011.2.02
8. Coshell, L., Mclver, R. G., Chang, R. X-ray computed tomography of Australian oil shales: non-destructive visualization and density determination. Fuel, 1994, 73(8), 1317–1321.
http://dx.doi.org/10.1016/0016-2361(94)90307-7
9. Tiwari, P., Deo, M., Lin, C. L., Miller, J. D. Characterization of oil shale pore structure before and after pyrolysis by using X-ray micro CT. Fuel, 2013, 107, 547–554.
http://dx.doi.org/10.1016/j.fuel.2013.01.006
10. Zhao, J., Feng, Z. C., Yang, D., Kang, Z. Study on distribution characteristics of pores and fissures inside oil shale under the CT experiment. Journal of Liaoning Technical University (Natural Science), 2013, 32(8), 1044–1049 (in Chinese).
11. Sun, G. W., Sun, W. J., Jiang, J. Y., Wang, C. H. Experimental study and quantitative characterization of effective porosity in cement-based composite materials. Industrial Construction, 2010, 40(11), 98–101 (in Chinese).
