To address the gas flow behaviors in bedded salt rock, an apparent permeability model considering Knudsen diffusion, pore surface diffusion, and pore heterogeneity was presented. The evolutions of gas permeability and gas flow behaviors with pressure were hinted by a gas seepage experiment carried out for model verification. The results show that the new apparent permeability model could accurately invert the seepage behaviors in the cores of salt rock and interlayer, with an average error of 2.39% and 1.22% for helium and nitrogen, respectively. When the pore pressure is 0.5 MPa, the permeability contribution of Knudsen diffusion accounts for 82.35% of the apparent permeability. When the pore pressure is higher than 1.24 MPa, the permeability of Knudsen diffusion is lower than that of viscous flow. Once the gas pressure is higher than 2 MPa, the permeability contribution of Knudsen effect is basically equal to 0. A special focus was given to the different gases in salt cavern gas storage, which indicated that the leakage ratio of hydrogen is the highest, followed by methane, and helium is the lowest, with 7.27%, 5.76%, and 4.58%, respectively during the 30 years operation period. This work could add further insights into the gas flow behaviors in the pore heterogeneous salt rock and be employed for tightness evaluation of salt cavern gas storage and pillar width design of adjacent salt caverns.

中文翻译：

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孔隙非均质层状盐岩气体输运模型：对盐穴储气库致密性评价的启示

为了解决层状盐岩中的气体流动行为，提出了考虑努森扩散、孔隙表面扩散和孔隙非均质性的表观渗透率模型。为模型验证而进行的气体渗流实验暗示了气体渗透率和气体流动行为随压力的变化。结果表明，新的视渗透率模型能够准确反演盐岩岩心和夹层的渗流行为，氦气和氮气的平均误差分别为2.39%和1.22%。当孔隙压力为0.5 MPa时，克努森扩散渗透率贡献占表观渗透率的82.35%。当孔隙压力高于1.24 MPa时，努森扩散渗透率低于粘性流渗透率。一旦气体压力高于2 MPa，努森效应的渗透率贡献基本等于0。特别关注盐穴储气库中的不同气体，发现氢气的泄漏率最高，其次是盐穴储气库。甲烷、氦气最低，30年运行期间分别为7.27%、5.76%和4.58%。这项工作可以进一步了解孔隙非均质盐岩中的气体流动行为，并可用于盐穴储气库的密封性评估和相邻盐穴的柱宽设计。