In order to evaluate the efficiency of producing gas from natural gas hydrate (NGH)

NGH dissociation under thermal stimulation is treated as a moving-boundary problem.Based on a mathematical model assuming that dissociation of hydrate in the porous media takes place in constant temperature boundary condition，the analytical temperature distributions in dissociated and undissociated zones were solved

and thermal efficiency and energy efficiency were derived.A comparison of hot water injection case and brine injection case for the same heat injection rate showed higher thermal and energy efficiency for the brine case than the hot water case.Thermal efficiency was commonly 40%—70%. During dissociation of hydrate by injecting 300—450 K

0—15%(mass) hot brine

energy efficiency varied between 7.4% and 11.3%. From this point of view

hot brine injection is a feasible and economical way of NGH production.