## 2 Materials and Methods
### Experimental Results and Analysis
The results are shown in Table 2.  
As can be seen in Table 2, the porosity increases with the increase in water content, the porosity decreases to a certain extent as the experiment proceeds, and the explanation of the specific phenomenon is as follows: before the experiment, the increase in the water content of the rock means that the water gradually fills up the pore space, and under the premise of not changing the skeleton structure of the rock particles, the porosity will be increased due to the water occupying the space. During the experiment, when the low water content rock is pressurized, the rock particles will be close to each other under pressure, and the pores will be compressed, resulting in a decrease in porosity; when the pressure is reduced, the rock will have a certain rebound, but it is difficult to completely recover to the initial state, and the porosity will continue to decrease after many cycles. The saturation of movable fluid is negatively correlated with the water content, and it also decreases to a certain extent as the experiment is carried out, in which the rock with a low water content decreases the most, and the explanation of the specific phenomenon is as follows: before the experiment, the water content increases, which means that more pores are occupied by the water, the space for movable fluid is compressed, and the saturation of the movable fluid is reduced naturally. In the experiment, every time the water pressure is pressurized, the water pressure will drive the movable fluid in the pore space to be discharged, resulting in a decrease in the movable fluid saturation. The initial movable fluid saturation of low water content rock is high, and more movable fluid can be extruded, so the decline is large; high water content rock originally has less movable fluid, and the amount that can be discharged is limited, so the decline is relatively small. The permeability will decrease with the increase in water content, and with the experiment, the permeability will also decrease to a certain extent, in which the permeability of the rock with high water content decreases more, the specific phenomenon is explained as follows: before the experiment, the water content increases, the water occupies more space in the pore space, which impedes the flow of the movable fluid, leading to the decrease in permeability. During the experiment, on the one hand, when pressurized, the water is redistributed in the pore space, which may block some of the pore channels, and on the other hand, the movement and rearrangement of the rock particles will change the connectivity of the pore space, and all of these will lead to a decrease in permeability. In \begin{table}
\begin{tabular}{c c c c c} \hline  & **Water Content \%** & **Porosity \%** & **Movable Fluid Saturation \%** & **Permeability** \\ \hline Pre-laboratory & 0 & 1.25 & 20.93742308 & 4.04775 \(\times\) 10\({}^{-5}\) \\  & 50\% & 1.29 & 16.56704005 & 3.95992 \(\times\) 10\({}^{-5}\) \\  & 80\% & 1.53 & 12.05056763 & 4.75 \(\times\) 10\({}^{-6}\) \\  & 100\% & 1.76 & 6.163999155 & 3.14 \(\times\) 10\({}^{-6}\) \\  & 0 & 1.16 & 18.43742308 & 3.65992 \(\times\) 10\({}^{-5}\) \\ Post-experiment & 50\% & 1.21 & 15.36704005 & 3.14775 \(\times\) 10\({}^{-5}\) \\  & 80\% & 1.49 & 11.25056763 & 3.88857 \(\times\) 10\({}^{-6}\) \\  & 100\% & 1.68 & 5.763999155 & 2.03 \(\times\) 10\({}^{-6}\) \\ \hline \end{tabular}
\end{table} 
Table 2: Comparison of porosity and movable fluid saturation permeability before and after experiments on specimens with different water contents. high water content rocks, most of the pore space was originally occupied by water, and in the process of pre-consolidation, the redistribution of water and the change in rock structure damage the pore connectivity more seriously, so the decrease in permeability is greater. At the same time, the rate of water infiltration affects the uniformity of water distribution in rock pores and microfractures as well as the time of action.