## 4 Results and Discussion  
### Repeatability of MIP Tests  
Normally, a repeatability test on the same sample should be carried out as previously tested. Because the samples remain contaminated with mercury after the MIP test, a regular repeatability should not be available for MIP tests. However, three representative samples from the same coal were chosen to evaluate the repeatability of MIP. HDG 6#, LL-DP 10#, YQ-WK 15# were selected for triplicate MIP tests and the remaining 8 samples were tested only once. Table 3 shows the results of the repeatability tests.  
\begin{table}
\begin{tabular}{c c c c c c c c} \hline \hline \multirow{2}{*}{**Sample No.**} & \multirow{2}{*}{**R\({}_{o,m}\) (\%)**} & \multirow{2}{*}{**Porosity (\%)**} & \multirow{2}{*}{\(d_{a}\) (nm)**} & \multicolumn{2}{c}{**Permeability**} & \multirow{2}{*}{\(De\) (m\({}^{2}\)/s)**} & \multirow{2}{*}{\(D^{\prime}\)} & \multirow{2}{*}{\(m\)} \\  & & & & & & & \\ \hline HDG 6\# & 0.68 & 14.7 & 13.80 & 3.24220 & 1.94 \(\times\) 10\({}^{-7}\) & 0.009 & 2.46 \\ BLG 6\# & 0.68 & 6.4 & 8.70 & 0.34166 & 5.34 \(\times\) 10\({}^{-8}\) & 0.002 & 2.18 \\ HYC 4\# & 0.65 & 12.3 & 10.60 & 2.07678 & 1.27 \(\times\) 10\({}^{-7}\) & 0.006 & 2.45 \\ LHJ 4\# & 0.46 & 6.15 & 7.10 & 0.08250 & 4.25 \(\times\) 10\({}^{-8}\) & 0.002 & 2.23 \\ LL-HJG 5\# & 1.34 & 8.55 & 10.62 & 0.23323 & 8.64 \(\times\) 10\({}^{-8}\) & 0.004 & 2.25 \\ LL-DP 10\# & 1.68 & 8.87 & 10.25 & 0.15094 & 8.70 \(\times\) 10\({}^{-8}\) & 0.004 & 2.28 \\ LL-SL 5\# & 1.19 & 10.83 & 26.12 & 0.23348 & 2.38 \(\times\) 10\({}^{-7}\) & 0.011 & 2.03 \\ LL-XM 5\# & 1.44 & 12.16 & 10.53 & 0.95305 & 1.24 \(\times\) 10\({}^{-7}\) & 0.006 & 2.45 \\ TY-DY 6\# & 2.56 & 8.55 & 11.32 & 0.05775 & 9.15 \(\times\) 10\({}^{-8}\) & 0.004 & 2.22 \\ GJ-DQ 4\# & 2.05 & 13.59 & 12.53 & 0.01065 & 1.64 \(\times\) 10\({}^{-7}\) & 0.008 & 2.45 \\ YQ-WK 15\# & 2.54 & 11.36 & 15.22 & 0.24810 & 1.60 \(\times\) 10\({}^{-7}\) & 0.007 & 2.25 \\ YQ-YK 15\# & 2.79 & 18.12 & 24.60 & 3.28539 & 3.95 \(\times\) 10\({}^{-7}\) & 0.018 & 2.34 \\ \hline \hline \end{tabular} Note: \(d_{a}\) = average pore size; \(De\) = effective gas diffusion coefficient; \(D^{\prime}\) = CH\({}_{4}\) diffusivity; \(m\) = cementation factor.  
\end{table}
Table 2: Porosity, permeability, effective diffusion coefficient and \(m\) values by MIP.  
\begin{table}
\begin{tabular}{c c c c c c} \hline \hline \multirow{2}{*}{**Sample No.**} & \multirow{2}{*}{**MIP Test**} & \multicolumn{3}{c}{**Porosity (\%)**} & \multirow{2}{*}{_da (nm)_} \\ \cline{3-4} \cline{6-6}  & & **Measured Value** & & **Avg \(\pm\) Standard Deviation** & **Measured Value** & **Avg \(\pm\) Standard Deviation** \\ \hline \multirow{3}{*}{HDG 6\#} & 1 & 15.62 & & 14.57 & \\  & 2 & 13.88 & 14.7 \(\pm\) 0.92 & 13.12 & 13.8 \(\pm\) 0.77 \\  & 3 & 14.6 & & 13.71 & \\ \hline \multirow{3}{*}{LL-DP 10\#} & 1 & 8.56 & & 10.12 & \\  & 2 & 9.06 & 8.87 \(\pm\) 0.31 & 10.4 & 10.25 \(\pm\) 0.15 \\  & 3 & 8.99 & & 10.23 & \\ \hline \multirow{3}{*}{YQ-WK 15\#} & 1 & 11.59 & & 15.41 & \\  & 2 & 11.45 & 11.36 \(\pm\) 0.32 & 15.3 & 15.22 \(\pm\) 0.27 \\ \cline{1-1}  & 3 & 11.04 & & 14.95 & \\ \hline \hline \end{tabular}
\end{table}
Table 3: Results of repeatability tests.