Nanoscale simulation of shale transport properties using the lattice Boltzmann method: permeability and diffusivity.
Nanoscale simulation of shale transport properties using the lattice Boltzmann method: permeability and diffusivity.
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使用晶格玻尔兹曼方法进行页岩输运特性的纳米级模拟：渗透率和扩散率
DOI：
10.1038/srep08089
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发表时间：
2015-01-28
影响因子：
4.6
通讯作者：
Tao W
中科院分区：
文献类型：
--
作者：
Chen L;Zhang L;Kang Q;Viswanathan HS;Yao J;Tao W
基于四川盆地页岩样品的扫描电镜（SEM）图像，采用马尔可夫链蒙特卡罗（MCMC）方法重构了页岩孔隙结构。对重建页岩进行孔隙度、孔径分布、比表面积、孔隙连通性等表征分析。采用晶格玻尔兹曼方法（LBM）模拟了重建页岩内的流体流动和Knudsen扩散。模拟结果表明，页岩的弯曲度远高于Bruggeman方程，而如此高的弯曲度导致了极低的固有渗透率。在含尘气体模型（DGM）的基础上，考虑Knudsen扩散对总流量的贡献，对固有渗透率进行校正，得到表观渗透率。在克努森数和压力的范围内的校正因子进行估计，并与文献中的经验相关性进行比较。在较宽的压力范围内，修正系数均大于1，说明改造页岩中Knudsen扩散对页岩气输运机制始终起作用。具体而言，我们发现校正因子的大部分值落在滑移和过渡区，没有观察到达西流动区。
Porous structures of shales are reconstructed using the markov chain monte carlo (MCMC) method based on scanning electron microscopy (SEM) images of shale samples from Sichuan Basin, China. Characterization analysis of the reconstructed shales is performed, including porosity, pore size distribution, specific surface area and pore connectivity. The lattice Boltzmann method (LBM) is adopted to simulate fluid flow and Knudsen diffusion within the reconstructed shales. Simulation results reveal that the tortuosity of the shales is much higher than that commonly employed in the Bruggeman equation and such high tortuosity leads to extremely low intrinsic permeability. Correction of the intrinsic permeability is performed based on the dusty gas model (DGM) by considering the contribution of Knudsen diffusion to the total flow flux, resulting in apparent permeability. The correction factor over a range of Knudsen number and pressure is estimated and compared with empirical correlations in the literature. For the wide pressure range investigated, the correction factor is always greater than 1, indicating Knudsen diffusion always plays a role on shale gas transport mechanisms in the reconstructed shales. Specifically, we found that most of the values of correction factor fall in the slip and transition regime, with no Darcy flow regime observed.
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影响因子：
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作者：
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