메탄 하이트레이트 생성에 대한 삼상 평형 조건 연구가 NaCl 3 wt% 수용액, MgCl₂ 3wt% 수용액에서 실험을 통해 이루어졌다. 이들 평형조건을 순수한 물에서의 평형조건과 비교하였다. 실험의 온도와 압력 범위는 NaCl 3wt% 수용액인 경우에 274.16-287.96K, 2,920-18,090 kPa 그리고, MgCl₂ 3wt% 경우에 272.86-286.41K, 2,910-11,840 kPa이었다. 고체상의 메탄 하이드레이트, 액상의 물 및 기상의 메탄으로 이루어진 삼상 평형 실험결과를 van der Waals-Platteeuw 모델을 기본으로 한 예측결과와 비교하였다. 메탄 하이드레이트는 고압과 저온의 평형 조건이 만족되는 심해의 천부 퇴적층에서 안정하게 존재할 수 있으며, 동해 남부 지역에 대한 지구물리학적 탐사 결과로부터 메탄 하이드레이트 안정 영역이 온도, 압력 그리고 geothermal gradient에 의해 존재할 수 있음이 밝혀졌다. 탐사지역의 수심 1,100m 지역에서의 메탄 하이드레이트 안정영역의 두께는 해저면으로부터 약 400m에서 550m까지로 전해질의 성분에 따라 조금씩 변하는 것으로 밝혀졌다.

Three-phase equilibrium conditions for forming methane hydrate were experimentally obtained in aqueous single electrolyte solutions containing 3wt% NaCl and 3 wt% MgCl₂. The experimental temperature and pressure ranges were 274.41-291.11K and 2,500-19,050 kPa for pure water, 274.16-287.96K and 2,920-18,090 kPa for NaCl 3wt% solution, 272.86-286.41K and 2,910-11,840 kPa for MgCl₂ 3wt% 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 440m beneath the seafloor and varied with the type of electrolytes.

Methane Hydrate Equilibrium Stability Field Electrolyte NaCl MgCl₂

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