Analysis of the influence of wettability on permeability in hydrate-bearing porous media using pore network models combined with computed tomography

The permeability of hydrate-bearing porous media is one of the most important factors in predicting fluid flow behavior, fluid distribution, and gas performance during hydrate exploitation. The wettability of porous media greatly affects the relative permeability of two-phase gas-water mixtures. In this paper, we extend our previous investigation into the effects of the wettability of porous media containing hydrates on their seepage properties using pore network models combined with X-ray computed tomography (CT). The simulation results show that in a uniform wetting system, increasing the contact angle reduces the wettability of hydrate-bearing porous media, increases the relative permeability of the water phase, and decreases the relative permeability of the gas phase at a given water saturation. In addition, increasing the diameter of quartz sand particles notably enhances these changes in the gas-water phase relative permeability. In a fractional-wetting system, increasing the fractional wettability and connectivity effectively reduces the residual gas saturation. Moreover, the capillary pressure distributions are highly dependent on the fractional wettability and quartz sand size. (C) 2015 Elsevier B.V. All rights reserved.