Model for investigating mechanical transport in fracture networks
Directional mechanical transport properties for anisotropic fracture systems were investigated. A determination was sought of when fracture systems can be treated like equivalent porous media in transport studies and a model that simulated mechanical transport in networks of fractures is introduced. The two important conditions necessary for measuring directional mechanical transport for an equivalent porous medium are a uniform flow field and a test section where the linear path length is constant. With these two conditions satisfied, mechanical transport parameters can be measured from the breakthrough curve for the fluid that flows within the test section. The hydraulic effective porosity was defined as the ratio of specific discharge to average linear velocity. In porous media transport studies, hydraulic effective porosity is directionally stable. Thus the shape of the polar plot of hydraulic effective porosity was used to test whether a fracture system behaved like an equivalent porous medium for transport. A numerical model was developed to simulate mechanical transport under steady flow in a network of fractures. The model incorporated the principles of laminar flow to calculate the location of stream tubes for fluid flowing from one side of a flow region to another. The model has been used to simulate mechanical transport in regular, anisotropic systems of continuous fractures. The results demonstrated that a fracture system which behaves as a continuum for fluid flux may not behave as a continuum for mechanical transport. 18 references, 14 figures, 2 tables.
- Research Organization:
- Lawrence Berkeley Lab., CA
- OSTI ID:
- 5414067
- Journal Information:
- Water Resour. Res.; (United States), Journal Name: Water Resour. Res.; (United States) Vol. 20:10; ISSN WRERA
- Country of Publication:
- United States
- Language:
- English
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