  The time evolution of the system of water in the Libersorb 23 (L23)
disordered nanoporous medium after the complete filling at excess pressure and
the subsequent removal of excess pressure has been studied. It has been found
that three stages can be identified in the relaxation of the L23-water system
under study. At the first stage, a portion of water at the removal of excess
pressure rapidly flows out in the pressure reduction time, i.e., following a
decrease in the pressure. It has been shown that, at temperatures below the
dispersion transition temperature $T < T_d = 284 K$, e.g., $T = 277 K$, the
degree of filling ${\theta}$ decreases from 1 to 0.8 in 10 s, following the
variation of excess pressure. At the second stage of relaxation, the degree of
filling ${\theta}$ varies slowly according to a power law ${\theta} \sim
t^{-\alpha}$ with the exponent ${\alpha} < 0.1$ in the time $t \sim 10^5$ s.
This corresponds to a slow relaxation of the formed metastable state of the
nonwetting liquid in the porous medium. At the third stage when $t > 10^5$ s,
the formed metastable state decays, which is manifested in the transition to a
power-law dependence ${\theta}(t)$ with a larger exponent. The extrusion-time
distribution function of pores has been calculated along with the time
dependence of the degree of filling, which qualitatively describes the observed
anomalously slow relaxation and crossover of the transition to the stage of
decay with a power-law dependence ${\theta}(t)$ with a larger exponent. It has
been shown that the relaxation and decay of the metastable state of the
confined nonwetting liquid at ${\theta}>{\theta_c}$ are attributed to the
appearance of local configurations of liquid clusters in confinement and their
interaction inside the infinite percolation cluster of filled pores.
