Advective Transport in Discrete Fracture Networks With Connected and Disconnected Textures Representing Internal Aperture Variability
Advective Transport in Discrete Fracture Networks With Connected and Disconnected Textures Representing Internal Aperture Variability
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具有代表内部孔径变化的连通和不连通纹理的离散裂缝网络中的平流传输
DOI：
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发表时间：
2019
影响因子：
5.4
通讯作者：
Liangchao Zou
中科院分区：
文献类型：
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作者：
Andrew Frampton;J. Hyman;Liangchao Zou
采用数值模型研究了具有孔径和渗透率内部变异的三维离散裂缝网络中的流动和输运。对三种不同的纹理类型进行了分析，考虑了不同的相关长度，表示内部变异性，并对相应的网络复杂性增加的域大小进行了分析。与光滑裂缝相比，离散裂缝网络的内部可变性通常会增加中间移动时间，并延迟大质量运输的到达时间。特别是连通性较弱的内部变率纹理，随着畴尺寸的增大，行程时间呈非线性增加，进一步延迟了体质量的到达。然而，具有强连通性的纹理可以减少中位数旅行时间，加速整体质量到达，但仅适用于有限范围的相关长度和域大小。随着域尺寸的增大，强连通性纹理的行程时间向经典多变高斯纹理的行程时间收敛。因此，考虑裂缝内部的可变性对于改善大规模离散裂缝网络中总体质量到达、流动通道、平流和反应性输运的保守估计具有潜在的重要意义。此外，对于具有强连通性的纹理和对应于中等连通性的经典高斯纹理，早期质量到达可以明显提前，但仅受弱连通性纹理的轻微影响。因此，考虑裂缝的内部变化对于准确估计早期溶质质量的到来也很重要。对预测输运建模的总体影响将取决于现实世界裂缝性岩石内部裂缝连通性结构的程度或缺乏程度。
Flow and transport in three‐dimensional discrete fracture networks with internal variability in aperture and permeability are investigated using a numerical model. The analysis is conducted for three different texture types representing internal variability considering various correlation lengths and for an increase in domain size corresponding to an increase in network complexity. Internal variability in discrete fracture networks generally increases median travel times and delays arrival of bulk mass transport when compared against reference cases without texture, corresponding to smooth fractures. In particular, internal variability textures with weak connectivity increase travel times nonlinearly with domain size increase, further delaying bulk mass arrival. Textures with strong connectivity can however decrease median travel times, accelerating bulk mass arrival, but only for limited ranges of correlation length and domain size. As domain size increases, travel times of textures with strong connectivity converge toward travel times obtained for classical multivariant Gaussian textures. Thus, accounting for internal fracture variability is potentially significant for improving conservative estimates of bulk mass arrival, flow channeling, and advective and reactive transport in large‐scale discrete fracture networks. Further, early mass arrival can arrive significantly earlier for textures with strong connectivity and classical Gaussian textures corresponding to intermediate connectivity but are only slightly affected by textures with weak connectivity. Thus, accounting for internal variability in fractures is also important for accurate estimates of early solute mass arrival. The overall impact on predictive transport modeling will depend on the extent of, or lack of, internal fracture connectivity structure in real‐world fractured rocks.