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Water Sorption and Transport in Shales: An Experimental and Simulation Study
Water Resources Research ( IF 5.4 ) Pub Date : 2021-01-14 , DOI: 10.1029/2019wr026888
Feng Yang 1, 2 , Bin Lyu 1 , Shang Xu 1
Affiliation  

Understanding water uptake and drainage in shales has important implications for both hydrocarbon extraction and hydraulic fracturing fluid disposal. This study reports gravimetric water sorption isotherms and kinetics of water transport in shales. Moisture mass transport profiles during water uptake and drainage processes were numerically simulated. Quantitative parameters characterizing the water transport properties were calculated and their dependences on water saturation were analyzed. An approach was proposed to evaluate the permeability of shales using dynamic water sorption. The reliability of the estimated results was verified by the experimental values using gas permeability measurements.The apparent diffusion coefficients of water sorption on shales were found to be between 1.0 × 10−12 and 1.5 × 10−11 m2/s. The apparent diffusion coefficient first increases with water saturation and remains stable at a moderately saturated condition. However, this coefficient decreases for shales with high water saturation. Apparent diffusion coefficients for the sorption process are almost equal to those for the desorption process, except at the moderate saturation condition. Liquid water (including adsorbed water) contributes more than 80% to the water transport, whereas water vapor mainly contributes to shales with low water saturation. The liquid water permeability determined by water sorption is consistent with the crushed‐rock permeability measured by gas expansion. A further reasonable agreement is achieved between the analytical gas permeability, as a function of water saturation, and the experimental gas phase permeability. Water sorption kinetics provide an indirect method for assessing the water transport properties as a function of water saturation when direct measurements are not available.

中文翻译:

页岩中的吸水与运水:实验与模拟研究

了解页岩中的吸水和排水对碳氢化合物提取和水力压裂液处置都具有重要意义。该研究报告了页岩中的重力吸水等温线和水传输动力学。数值模拟了吸水和排水过程中的水分传质曲线。计算表征水传输特性的定量参数,并分析其对水饱和度的依赖性。提出了一种利用动态水吸附法评价页岩渗透率的方法。页岩的吸水率表观扩散系数为1.0×10 -12至1.5×10-11  m 2/ s。表观扩散系数首先随水饱和度增加而增加,并在中等饱和条件下保持稳定。但是,对于含水饱和度较高的页岩,该系数会降低。除了在中等饱和条件下,吸附过程的表观扩散系数几乎等于解吸过程的表观扩散系数。液态水(包括吸附的水)对水输送的贡献超过80%,而水蒸气主要对水饱和度低的页岩起作用。通过吸水确定的液态水渗透率与通过气体膨胀测量的碎石渗透率一致。在作为水饱和度的函数的分析气体渗透率与实验气相渗透率之间达成了进一步的合理协议。
更新日期:2021-02-12
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