A 3D model was established to study the influence of ice formation on the process of gas production during gas hydrate dissociation by depressurization. Considering effects of ice, the temperature field and absolute permeability of the reservoir were analyzed. Additionally, the cumulative gas production was compared with and without ice formation. The results indicated that the temperature change is a process of repeated fluctuations because ice affected the heat transfer in the reservoir. Meanwhile ice formation can reduce the absolute permeability near the production boundary significantly. And then, the permeability can recover from the boundary because of the constant temperature boundary. Moreover, compared to the condition without ice effects, the cumulative gas production with ice formation is more in the initial stage, and then it will become much less. And the gas production rate fluctuates with freezing and melting.
Keywords hydrate dissociation, ice effects, temperature, permeability, gas production