Numerical simulation of natural gas hydrate production by depressurization in salt-water system

Considering the distribution of salt concentration, a mathematical model of production of natural gas hydrate reservoir by depressurization in salt-water system was established according to equations of conservation of mass and energy, kinetics equations of natural gas hydrate decomposition. The process of non isothermal flow in hydrate reservoir with three phases and eight components can be described by this model. The production behaviors of hydrates in pure-water and salt-water system were simulated under one dimension. The results show that the simulated results agree well with experimental results. In salt-water system, the salt affects phases balance of hydrates and accelerates the hydrates decomposition, and the pressure spreads much more quickly than that in pure-water system, which results in a big fluctuation of instantaneous gas production rate both in experiment and simulation.