The inhibit behavior of fluids migration on gas hydrate re-formation in depressurized-decomposed-reservoir

Abstract

Hydrate re-formation can lead to the blockage of gas recovery during natural gas hydrates production process. However, the hydrate re-formation induced by fluid migration is ignored. In this work, hydrate re-formation behaviors in porous media were investigated via two types of the fluid migration: gas migration and liquid migration. The gas migration was conducted by the following two ways: migration from top to bottom, and migration from bottom to top. The marine soil from South China sea was utilized to reconstruct hydrate samples. The results indicated that the average temperature rise with liquid migration is twice as large as that of the gas migration. What's more, the maximum temperature increment of decomposed-reservoir reaches 9 K. In addition, it was found that there was a duration of 60 min until hydrate re-formation at the end of the liquid migration process. Surprisingly, the fluid migration had a positive influence on inhibiting hydrate re-formation. The findings of this study suggest that the fluid migration could inhibit the hydrate re-formation in depressurized-decomposed-reservoir.