Macro-scale effective constitutive relationships for two-phase flow processes in heterogeneous porous media with emphasis on the relative permeability-saturation relationship
Macro-scale effective constitutive relationships for two-phase flow processes in heterogeneous porous media with emphasis on the relative permeability-saturation relationship
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DOI：
10.1016/j.jconhyd.2004.07.009
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发表时间：
2005-01-01
影响因子：
3.6
通讯作者：
Manthey, S
中科院分区：
文献类型：
--
作者：
Braun, C;Helmig, R;Manthey, S
宏观尺度模拟在地下致密非水相液体（DNAPLs）污染的评估和修复中发挥着重要作用。这些模拟需要宏观尺度的有效参数，以避免地质构造的详细离散化。本文从观察到的多相流过程在宏观尺度上的非均质性影响出发，提出了从局部尺度到宏观尺度的本构关系推导过程。该方法基于（毛细）力平衡的假设，从而允许应用渗透模型。这就得到了不同毛细管压力下的饱和度分布。平均这些分布可以得到宏观毛细管压力-饱和度关系。对于饱和分布，根据结构和流动方向计算相对渗透率和有效电导率。在重整化方法的帮助下，这些都是平均的。在宏观尺度上，相对渗透率-饱和度关系的演化表现出与饱和度相关的各向异性和显著的非润湿相残余饱和度（局部尺度上没有假设）。各向异性反映了所考虑的系统的基本结构，不需要详细了解。(C) 2004 Elsevier b.v.版权所有
Macro-scale simulations often play an important role in the assessment and remediation of contamination by dense non-aqueous phase liquids (DNAPLs) in the subsurface. Effective parameters for the macro scale are required for these simulations in order to avoid a detailed discretisation of the geological structures. Starting from the observed influence of heterogeneities on multiphase flow processes at the macro scale, we present an upscaling procedure from the local to the macro scale for the derivation of constitutive relationships for multiphase flow processes. The approach is based on the assumption of an equilibrium of (capillary) forces, which allows the application of a percolation model. This results in saturation distributions for different capillary pressures. Averaging these distributions gives rise to a macroscopic capillary pressure-saturation relationship. For the saturation distribution, relative permeabilities and effective conductivities are computed depending on the structure and the flow direction. These are averaged with the help of the renormalisation method. The evolving relative permeability-saturation relationship for the macro scale shows a saturation-dependent anisotropy and pronounced residual saturations of the nonwetting phase (which were not assumed for the local scale). The anisotropy reflects the underlying structure of the considered system that needs not to be known in detail. (C) 2004 Elsevier B.V All rights reserved.