PRESSURE AND TEMPERATURE CONDITIONS FOR METHANE HYDRATE DISSOCIATION IN SODIUM-CHLORIDE SOLUTIONS

The pressure and temperature conditions were experimentally determined for methane hydrate dissociation in sodium chloride solutions, and an empirical equation of the conditions was obtained in the pressure ran ge up to 18 MPa. The present results indicate that the maximum depth o f oceanic sediments where methane hydrate is stable increases as water depth to seafloor increases, and that the maximum depth in saline wat er is smaller than that in pure water. The difference in the depth bet ween saline and pure waters increases with decreasing the water depth, indicating that salinity of pore water affects significantly the amou nt of methane hydrate in oceanic sediments, in particular, beneath sea floor at relatively shallow depths.