## 6 Conclusions  
The high gas content of valuable coking coals in the Kuzbass predetermines the need for gas pre-drainage during field development. This creates preconditions for CBM industrial production, which is still insignificant in Russia.  
As the confining pressure increased by 8 times (from 1 MPa to 8 MPa), the coal permeability perpendicular to the butt cleat direction decreased by 6.7 times (from 60 mD to 9 mD). The average coal cleat compressibility was 0.085 MPa\({}^{-1}\).  
The tested coking coal had a pronounced microblock structure with two developed fracture systems: dominant face cleats and secondary butt cleats. In the unloaded state, the width of the face cleats was 12-13 \(\upmu\)m, the width of the butt cleats was 8-9 \(\upmu\)m, and the angle between them was 102.3\({}^{\circ}\). The average sizes of the coal matrix microblocks between the face cleats and between the butt cleats were 2213 and 925 \(\upmu\)m, respectively. The coal permeability anisotropy was determined by the results of filtration tests, microstructural analysis data, and the standard matchstick geometry model of coal. It was found that a  
\begin{table}
\begin{tabular}{c c c c} \hline \hline \multirow{2}{*}{**Coal Seam Name**} & \multirow{2}{*}{**Depth, m**} & **The Predicted Permeability of the Coking Coals Perpendicular to the Butt Cleat Direction, mD** & **The Predicted Permeability of the Coking Coals Perpendicular to the Face Cleat Direction, mD** \\ \hline \multicolumn{4}{c}{Nikitinsky field} \\ \hline
18 & 815 & 23.4 & 15.8 \\
19 & 850 & 22.3 & 15.1 \\
22 & 1050 & 16.8 & 11.3 \\
26 & 1175 & 14.1 & 9.5 \\
30 & 1245 & 12.7 & 8.6 \\
32 & 1315 & 11.5 & 7.8 \\
33 & 1350 & 11 & 7.4 \\ \hline \multicolumn{4}{c}{Tambovsky field} \\ \hline
18 & 1090 & 15.9 & 10.7 \\
22 & 1330 & 11.3 & 7.6 \\ n/a & 1460 & 9.4 & 6.3 \\
30 & 1550 & 8.3 & 5.6 \\
32 & 1675 & 6.9 & 4.7 \\
33 & 1760 & 6.1 & 4.1 \\
45 & 1915 & 4.9 & 3.3 \\ \hline \hline \end{tabular}
\end{table}
Table 5: The predicted coking coal permeabilities for stress regime, described by uniaxial strain and horizontal stress across cleats.  
3:2 ratio of face cleat permeability to butt cleat permeability was observed for coals from the Leninsky area, Kuzbass.  
On the basis of the obtained experimental and analytical data, we predicted the permeability for gas-bearing coking coals of the Nikitinsky, Tarsminsky and Tambovsky deposits of the Leninsky district, Kuzbass. The dependences of coal permeability change on depth were obtained. The prediction was performed assuming conditions of uniaxial strain of rocks, which made it possible to model the stress-strain state of horizontal layers on a regional scale. It was found that in the depth intervals of the coking coals, as the depth increased, their permeability decreased by 61-75% in the Nikitinsky field and by 74-87% and 69-82% in the Tambovsky and Tarsminsky fields, respectively. The permeability anisotropy coefficient along the bedding plane was 1.5, which can be used to design gas drainage schemes for the considered coals.  
The obtained results showed the perspective of industrial CBM production from gas-bearing coking coal seams in the Leninsky area, Kuzbass. Taking into account the poor knowledge of the regularities of coal permeability changes in the region, we can say that the obtained results are of practical interest and can be used to select promising objects and to design industrial operations for CBM extraction in Kuzbass.  
Conceptualization, T.S. and S.S.; methodology, T.S.; validation, T.S. and S.S.; formal analysis, S.S.; investigation, T.S.; writing--original draft preparation, T.S.; writing--review and editing, S.S. All authors have read and agreed to the published version of the manuscript.  
This research was funded by the Russian Science Foundation, grant number 19-77-00069.  
Not applicable.  
The authors declare no conflict of interest.