Permeability experiments on the methane hydrate in quartz sands and its model verification

The permeability of porous media is an important physical parameter that affects the exploitation of natural gas hydrate. At present, however, the measurement methods and porous media used for investigating the permeability are so different that neither well-recognized experiment methods nor measurement results are available yet. In this paper, a one-dimensional test apparatus was developed to measure the permeability of porous media with methane hydrate. By virtue of this apparatus, methane hydrate was generated and the flow rate and pressure difference of inflow liquid water were measured in a stable flow pattern. Then, based on the basic principle of the Darcy's Law, the permeability of 30-40 mesh quartz sands with a methane hydrate system was calculated using steady-state water injection. And the experimental results were obtained. First, this apparatus can provide the flow rates and pressure differences of stable fluid under constant pressures and temperatures, so it satisfies the basic conditions of the Darcy's Law and consequently the permeability is calculated. Second, with this apparatus, the methane hydrate saturation in permeability experiments can be controlled effectively, so that the reliability and repeatability of permeability measurement of methane hydrate bearing quartz sands are ensured. Third, methane hydrate crystals are formed and gradually grow in the pore center, occupying the pore space and blocking the flow channel. And the liquid effective permeability decreases sharply with the increase of methane hydrate saturation. Fourth, the permeability calculated by the Masuda, Dai and Li models is 13.0, 7.0 and 4.0, respectively and the calculated values are in accordance with the experimental results. These research results provide experimental data and a theoretical calculation basis for the quantification of fluid permeability of methane hydrate bearing porous media.