A model for water permeability reduction in hydrate-bearing sediments is presented by considering capillary effect in hydrate nucleation. Both grain-coating and pore-filling cases are considered. The model is developed from a series of lattice Boltzmann flow simulations. Results show that the permeability decreases quasi-linearly with increasing hydrate saturation during grain-coating nucleation and that the permeability tends to be higher than predicted by previous analytical models, in which capillarity is not taken into account. The permeability follows unique reduction curve and is not so sensitive to initial sediment bulk density and grain size distribution. Simulations further show that there is a transition zone at Shyd = 0.3~0.4, where permeability reduction trend switches from grain-coating model to pore-filling model. Analyses of tortuosity and surface area confirm that the permeability reduction mechanisms result from pore-channel blocking in grain-coating case and pore size reduction in pore-filling case.
Bibliographical noteFunding Information:
This work was supported by the Korea CCS R&D Center grant, the National Research Foundation of Korea grant, and the New and Renewable Energy Program of the Korea Institute of Energy Technology Evaluation and Planning grant funded by the Korean Government (MSIP) (2012-0008929, 2011-0030040, and 20133030000240) and was also supported by the Gas Hydrate Research fund (DE-FE-0009927) from the Department of Energy.
All Science Journal Classification (ASJC) codes
- Earth and Planetary Sciences(all)