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Lubrication theory analysis of the permeability of rough-walled fractures
19A
921141 Approximate solution of linear flow in naturally fractured reservoirs Aguilera, R Can Pet Technol V30, N3, May-June 1991, P86-90 Linear flow in a naturally fractured reservoir is analysed using a conventional dual porosity model (no matrix-matrix transfer). It is demonstrated that storativity ratio, fracture porosity, and distance between natural fractures can be obtained using a logarithmic plot of pressure change against time. Storativity ratio and hydraulic fracture length can be calculated from information in the plot of pressure change against square root of time.
921142 Subsidence effects on clay barriers Jessberger, H L; Stone, K J L Geotechnique V41. N2. June 1991, P185-194 Centrifuge model tests at up to 50g were used to examine the behaviour of simulated cover or base liners subject to differential settlements. Plane model barriers of kaolin or sand/silica flour/bentonite (SSB) were used. Physical deterioration was monitored photographically and hydraulic properties assessed throughout the deformation process. With no overburden, tension cracks readily formed in kaolin barriers. The presence of overburden suppressed this cracking and little liner efficiency deterioration was seen. The SSB liners show high deformation resistance, and there is little evidence of tension cracking or deterioration in performance.
921145 Comparison of field-monitored and numerically predicted moisture movement in unsaturated soil Thomas, H R; Rees, S W Int J Num Anal iWeth Geomech VI5, N6, June 1991, P417431 Flow in an unsaturated soil mass has been numerically modelled using an approach based on a finite element solution to Richards equation, adopting a finite difference recurrence relation to model the transient nature of the problem. Numerical results are compared to field measurements of volumetric water content made at a site of Kimmeridge clay subject to seasonal moisture changes alone. The numerical model is seen to adequately represent field behaviour over the depth of interest. 921146 Lubrication theory analysis of the permeability of roughwalled fractures Zimmerman, R W; Kumar, S; Bodvarsson, G S lnt J Rock Mech Min Sci V28, N4, July 1991. P325-331 Flow through rough walled fractures is complex. The solutions to the 3D Navier-Stokes equations to describe such flow are difficult to obtain and numerical simulations impractical, thus the simpler Reynold's lubrication equation is often substituted. Lubrication theory is applied to flow through idealised sinusoidal and sawtooth aperture profiled joints and analytical solutions obtained for different permeabilities. Results are compared to those of numerical solutions from lubrication theory for joints of random surfaces and numerical and high-order perturbation solutions to the Navier-Stokes equations for flow in fractures with sinusoidally varying aperture.
921143 Design of bentonite/crushed rock seals Ouyang, S; Daemen, J J K Geotech Geol Engng V9, NI, March 1991, P63-72
921147 Simple model for the migration of radionuclides through colloidal transport in a fracture formation (In French) Castaing, R J Hydroi V125. NIl2, June 1991, P55-92
Bentonite/crushed rock mixtures are often used as hydraulic barriers. Bentonite content and the gradation of the rock component are the primary parameters in seal design. The effect of crushed rock gradation on bulk porosity and permeability of systems of crushed tuff particles has been investigated. The bulk porosity of these systems in the presence of bentonite, and the effects of gradation of the tuff on occupancy percentage and saturated water content of the tuff are discussed. Compaction energy higher than standard Proctor is required to reduce bulk porosities of mixtures with more than 25% by weight of bentonite.
The case is considered where nuclides from a repository are transported as stable aggregates or colloids, small enough to follow the groundwater flow, in addition to transport in aqueous solution. A simple model for transport of solute and colloidal phases in a fissure of constant aperture is presented. Colloids are assumed to dissolve immediately solute concentration falls below solubility level due to sorption on to fracture walls or diffusion into the matrix. Analytical solutions are obtained and their validity, in view of assumptions made, is discussed.
921144 Method to determine formation constants of leaky aquifers, and its application to pumping test data. Computer note Kohlbeck, F; Alvarez, A Ground Water 1129, N3, May-June 1991, P425-429 A method based on minimisation of the sum of squares of differences between drawdown in an observation well and theoretical values from the Hantush and Jacob formula is presented for calculation of transmissivity, storage coefficient, and leakage coefficient of a leaky aquifer from pumping test data. No user defined starting points are necessary. Error estimates for the parameters are given. A practical application is shown.
921148 Relations between impulse responses and the hydrodynamic regime of systems for artificial tracer for the interpretation of tracer test: theory and application on a laboratory column (In French) Dzikowski, M; Carlier, E; Crampon, N; de Marsily, G J Hydrol V125, NI/2, June 1991, Pl29-148 Theoretical relations are established between the impulse response to an injection of a tracer and the steady state rate of flow in a circular conduit under laminar conditions. These relations depend on the constants of the physical system as a function of flow rate. Impulse responses were also calculated by representing mass transfer in porous materials by the random walk method, allowing relations to be established under variable flow conditions. Laboratory tracer tests in columns are used to quantitatively validate the relations.
© 1992 Pergamon Press plc. Reproduction not permitted
921141 Approximate solution of linear flow in naturally fractured reservoirs Aguilera, R Can Pet Technol V30, N3, May-June 1991, P86-90 Linear flow in a naturally fractured reservoir is analysed using a conventional dual porosity model (no matrix-matrix transfer). It is demonstrated that storativity ratio, fracture porosity, and distance between natural fractures can be obtained using a logarithmic plot of pressure change against time. Storativity ratio and hydraulic fracture length can be calculated from information in the plot of pressure change against square root of time.
921142 Subsidence effects on clay barriers Jessberger, H L; Stone, K J L Geotechnique V41. N2. June 1991, P185-194 Centrifuge model tests at up to 50g were used to examine the behaviour of simulated cover or base liners subject to differential settlements. Plane model barriers of kaolin or sand/silica flour/bentonite (SSB) were used. Physical deterioration was monitored photographically and hydraulic properties assessed throughout the deformation process. With no overburden, tension cracks readily formed in kaolin barriers. The presence of overburden suppressed this cracking and little liner efficiency deterioration was seen. The SSB liners show high deformation resistance, and there is little evidence of tension cracking or deterioration in performance.
921145 Comparison of field-monitored and numerically predicted moisture movement in unsaturated soil Thomas, H R; Rees, S W Int J Num Anal iWeth Geomech VI5, N6, June 1991, P417431 Flow in an unsaturated soil mass has been numerically modelled using an approach based on a finite element solution to Richards equation, adopting a finite difference recurrence relation to model the transient nature of the problem. Numerical results are compared to field measurements of volumetric water content made at a site of Kimmeridge clay subject to seasonal moisture changes alone. The numerical model is seen to adequately represent field behaviour over the depth of interest. 921146 Lubrication theory analysis of the permeability of roughwalled fractures Zimmerman, R W; Kumar, S; Bodvarsson, G S lnt J Rock Mech Min Sci V28, N4, July 1991. P325-331 Flow through rough walled fractures is complex. The solutions to the 3D Navier-Stokes equations to describe such flow are difficult to obtain and numerical simulations impractical, thus the simpler Reynold's lubrication equation is often substituted. Lubrication theory is applied to flow through idealised sinusoidal and sawtooth aperture profiled joints and analytical solutions obtained for different permeabilities. Results are compared to those of numerical solutions from lubrication theory for joints of random surfaces and numerical and high-order perturbation solutions to the Navier-Stokes equations for flow in fractures with sinusoidally varying aperture.
921143 Design of bentonite/crushed rock seals Ouyang, S; Daemen, J J K Geotech Geol Engng V9, NI, March 1991, P63-72
921147 Simple model for the migration of radionuclides through colloidal transport in a fracture formation (In French) Castaing, R J Hydroi V125. NIl2, June 1991, P55-92
Bentonite/crushed rock mixtures are often used as hydraulic barriers. Bentonite content and the gradation of the rock component are the primary parameters in seal design. The effect of crushed rock gradation on bulk porosity and permeability of systems of crushed tuff particles has been investigated. The bulk porosity of these systems in the presence of bentonite, and the effects of gradation of the tuff on occupancy percentage and saturated water content of the tuff are discussed. Compaction energy higher than standard Proctor is required to reduce bulk porosities of mixtures with more than 25% by weight of bentonite.
The case is considered where nuclides from a repository are transported as stable aggregates or colloids, small enough to follow the groundwater flow, in addition to transport in aqueous solution. A simple model for transport of solute and colloidal phases in a fissure of constant aperture is presented. Colloids are assumed to dissolve immediately solute concentration falls below solubility level due to sorption on to fracture walls or diffusion into the matrix. Analytical solutions are obtained and their validity, in view of assumptions made, is discussed.
921144 Method to determine formation constants of leaky aquifers, and its application to pumping test data. Computer note Kohlbeck, F; Alvarez, A Ground Water 1129, N3, May-June 1991, P425-429 A method based on minimisation of the sum of squares of differences between drawdown in an observation well and theoretical values from the Hantush and Jacob formula is presented for calculation of transmissivity, storage coefficient, and leakage coefficient of a leaky aquifer from pumping test data. No user defined starting points are necessary. Error estimates for the parameters are given. A practical application is shown.
921148 Relations between impulse responses and the hydrodynamic regime of systems for artificial tracer for the interpretation of tracer test: theory and application on a laboratory column (In French) Dzikowski, M; Carlier, E; Crampon, N; de Marsily, G J Hydrol V125, NI/2, June 1991, Pl29-148 Theoretical relations are established between the impulse response to an injection of a tracer and the steady state rate of flow in a circular conduit under laminar conditions. These relations depend on the constants of the physical system as a function of flow rate. Impulse responses were also calculated by representing mass transfer in porous materials by the random walk method, allowing relations to be established under variable flow conditions. Laboratory tracer tests in columns are used to quantitatively validate the relations.
© 1992 Pergamon Press plc. Reproduction not permitted