전해질이 메탄 하이드레이트 평형조건과 안정 영역에 미치는 영향

Abstract

Three-phase equilibrium conditions for forming methane hydrate were experimentally obtained in aqueous single electrolyte solutions containing 3 wt% NaCl and 3 wt% MgCl₂. The experimental temperature and pressure ranges were 274.41-291.11 K and 2,500-19,050 ㎪ for pure water, 274.16-287.96 K and 2,920-18,090 ㎪ for NaCl 3 wt% solution, 272.86-286.41 K and 2,910-11,840 ㎪ for MgCl₂3 wt% solution, respectively. The experimental three phase equilibria consisting of solid methane hydrate, liquid water and gaseous methane were compared with the predicted values calculated from the van der Waals-Platteeuw based model. Methane hydrate could be stable under specific temperature and pressure condition that occurs in the ocean floor sediments. Geophysical survey was implemented in the southern area of the East Sea, and the methane hydrate stability field was determined by simultaneously considering temperature, pressure and geothermal gradient obtained from the survey and well data. In the study area, methane hydrates might possibly exist in the sediments below the water depths of about 100 m, and the length of stability field appeared to be located at about 440 m beneath the seafloor and varied with the type of electrolytes.