Characterizing the pore system of green shales from the Masty location (Czech Republic)

0496529 - ÚGN 2019 DE eng A - Abstrakt
Ruppenthalová, Lucie - Möllmer, J. - Kolesnikov, A. - Uhlig, H.
Characterizing the pore system of green shales from the Masty location (Czech Republic).
Porotec Workshop - Book o Abstracts. Niedernhausen: Porotec, 2018. s. 36-36.
[Porotec Workshop /19./. 13.11.2018-14.11.2018, Niedernhausen]
Institucionální podpora: RVO:68145535
Klíčová slova: green shales * pore space * macroporous material
Obor OECD: Analytical chemistry

Shales from the Czech Republic are basic igneous rocks, fine-grained to medium grained material generally used for construction industry. As crushed stone it can be used for concrete due to their good chemical, thermal and mechanical properties. The shales also occur in the locations of a potential geothermal drill holes. In this case it is important to know not only thermal properties of shales it is also necessary to have an idea about their pore structure. Because the pore system can affect other specific properties of shales, e.g. transport of fluids or gas storage. This is a desirable information in the project of geothermal energy. Therefore, the Nitrogen sorption at 77 K was applied to characterize the pore system of green shales with 5 - 7 mm grain size from the Czech Republic (Masty location). This grain size was chosen because is very close to the real rock. The adsorption isotherms of Nitrogen show a combination of hysteresis loops corresponding to IUPAC types H2 and H3 indicating ink-bottle and slit-shaped pores.[1] Based on the shape of the isotherms, the pore size distribution indicates a predominantly macroporous character of the samples, with a small portion of mesopores around 2 – 4 nm (no micropores are detected by t-plot method). The obtained specific surface area was very low, more precisely in the range of 0.13 – 0.38 m2/g and differs by comparing all samples. The same applies to the adsorbed amount and the total pore volume. Mercury porosimetry was used for the determination of macropores and for representation of overall pore space of green shales. This method confirmed the predominantly macroporous character of the samples with pores larger than 280 nm. But for one sample of green shales, this method also showed a presence of mesopores of about 23 nm. The total porosity of green shales was very low, from 0.15 to 0.3 %. This information confirms the conclusion that green shales have a compact structure with a small amount of cracks and slits in a natural sample as it was confirmed by thin section microscopy.
These results can be helpful for better understanding the pore structure of shales and its effects on other properties, e.g. such as transport mechanisms.

Trvalý link: http://hdl.handle.net/11104/0289279