Theory of Matrix and Fracture Flow Regimes in Unsaturated, Fractured Porous Media
Theory of Matrix and Fracture Flow Regimes in Unsaturated, Fractured Porous Media
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非饱和裂隙多孔介质中的基质和裂隙流态理论
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发表时间：
1991
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通讯作者：
J. Nitao
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作者：
J. Nitao
二维非饱和裂缝-基质体系的流动特性表征为临界通量q*{下标f} = {phi}(S{下标S}{减}S{下标i})D{下标m}，其中{phi}为基质孔隙度，S{下标S}最大基质饱和度，S{下标i}初始饱和度，D{下标m}基质吸吸扩散系数常数。如果进入裂缝的流量q{sub f}满足q{sub f} {much_gt} q*{sub f}，则流场以裂缝为主；而当q{sub f} {much_lt} q*{sub f}时，流体以基质为主，体系表现为单一等效介质，裂缝与基质之间存在毛细平衡。如果裂缝入口有水池，则控制流动行为的不是临界流量，而是临界裂缝导流系数K*{sub f}，或由“立方定律”得出的相应临界孔径2b*。裂缝孔径2b大的岩石b{sup 3} {much_gt} b*{sup 3}以裂缝为主，裂缝孔径小的岩石b{sup 3} {much_lt} b*{sup 3}以基质为主。数值模拟验证了预测裂缝前缘运动的理论和近似解析解。15个参考文献。， 7个无花果。， 4个标签。
The flow behavior of a two-dimensional, unsaturated fracture-matrix system is characterized by a critical flux q*{sub f} = {phi}(S{sub s} {minus} S{sub i})D{sub m} where {phi} is matrix porosity, S{sub s} maximum matrix saturation, S{sub i} initial saturation, and D{sub m} matrix imbibition diffusivity constant. If the flux q{sub f} into the fracture satisfies q{sub f} {much_gt} q*{sub f}, the flow field is fracture-dominated; whereas, if q{sub f} {much_lt} q*{sub f}, the flow is matrix-dominated, and the system behaves as a single equivalent medium with capillary equilibrium between fracture and matrix. If the fracture entrance is ponded, the critical fracture hydraulic conductivity K*{sub f}, or corresponding critical aperture 2b* from the ``cubic law,`` controls the flow behavior instead of the critical flux. Rocks with fracture apertures 2b that are sufficiently large, b{sup 3} {much_gt} b*{sup 3}, have flow that is fracture-dominated while rocks with small aperture fractures, b{sup 3} {much_lt} b*{sup 3}, will be matrix-dominated. Numerical modeling verifies the theory and tests approximate analytical solutions predicting fracture front movement. 15 refs., 7 figs., 4 tabs.