Abstract: In order to simulate the real environment in the sea area,these experiments were carried out to study the effects of sodium chloride,initial saturation of the reservoir and replacement compressive stress on the liquid CO₂replacement-exploitation of natural gas hydrate in the sea area under the rich water condition.This study shows that under the condition of triaxial stress and porosity about46.70%,the sodium chloride system has little effect on the CH₄replacement efficiency,but it inhibits the CO₂hydrate synthesis.There is a negative correlation between initial reservoir saturation and CH₄replacement efficiency.In addition,a high reservoir water content is more favorable for CO₂storage.The CH₄replacement efficiency increases with the increasing replacement compressive stress,the increase of replacement compressive stress provides a high driving force for the CO₂hydrate formation,thereby improving the CO₂sequestration efficiency.