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Interpretation of field tracer tests of a single fracture using a transient solute storage model
122A selection are also examined, and areas where experimental methods or theoretical interpretation of results may be improved are identified. 893122 Gamma-camera imaging of oil displacement in thin slabs of porous media Huang, Y B; Gryte, C C J Pet Technol V40, NIO, Oct 1988, P1355-1360 A porous sintered glass slab was characterised by gamma camera imaging after saturation with a solution containing Tc 99 to obtain a reference picture. After washing and drying, it was saturated with oil, which was displaced by an aqueous tracer solution. The displacement was followed using gamma imaging. This method is seen to be a useful quantitative technique to investigate fluid flow in porous media. Corrections of data for radioactive decay and image degradation are described. 893 i 23 Diagrams considering well resistance for designing spacing ratio of gravel drain. Technical note Onoue, A Soils Found V28, N3. Sept 1988, P160-168 The finite difference method is used to analyse effectiveness of gravel drains constructed to prevent liquefaction of sandy soils by earthquakes. The method is based on the pore pressure generation curve. Results are presented as a series of design charts for determination of optimum drain spacing. 893124 Stochastic analysis of solute arrival time in heterogeneous porous media Shapiro, A M; Cvetkovic, V D Water Resour Res V24, NIO, Oct 1988. P1711-1718 Solute movement in heterogeneous porous media is analysed by considering the solute arrival time at a plane perpendicular to mean direction of fluid motion, defined in terms of the stochastic properties of the hydraulic conductivity. This flux arrival analysis defines the flux averaged concentration or rate of mass arrival. Comparisons are made with previous analysis based on Lagrangian interpretation of advective particle motion. Results are important to study of subsurface pollution or tracer transport. 893125 Coupled groundwater flow and solute transport with fluid density strongly dependent upon concentration Herbert, A W; Jackson. C P: Lever, D A Water Resour Res V24. NIO, Oct 1988. P1781-1795 Flow of a salt solution with significant density variation through a porous medium, as may be encountered around repositories in salt rocks, is analysed. Governing equations are formulated and incorporated in the finite element code NAMMU, and applied to an example problem from the HYDROCOIN project. Special numerical techniques were used to solve the problem: parameter stepping to handle nonlinearity, and mixed interpolation for modelling the velocity. 893 ! 26 Generalized Radial Flow model for hydraulic tests in fractured rock Barker. J A Water Resour Res V24. NIO. Oct 1988. P1796-1804 One, two or three dimensional flow may be appropriate for analysis of borehole hydraulic tests, depending on fracture geometry. The Generalized Radial Flow (GRF) model allows generalisation of the flow dimension to nonintegral values, while retaining assumptions of radial flow and homogeneity. (
A mathematical description of the G R F model and equations relating to common hydraulic tests are presented. Conceptual problems of the model and problems in relating it to field data are discussed. 893127 Discrimination among one-dimensional models of solute transport in porous media: implications for sampling design Knopman, D S; Voss, C I Water Resour Res V24, N I l . Not' 1988, P1859-1876 Solute transport models require specification of field scale parameters, which may not be easy to obtain, and direct verification is difficult. Comparison of performance of one model with another, model discrimination,where observations from designed sampling rounds are used to test hypotheses, is often more practical. Two variables in model discrimination are addressed, effects of solute concentration on transport and optimisation of sampling strategy. Specific examples of model error are examined, and sampling designs proposed. 893128 Stochastic analysis of paths of high hydraulic conductivity in porous media Silliman, S E; Wright, A L Water Resour Res V24. N i l . Noe 1988. P1901-1910 Representation of a single, nonrandom "effective' conductivity for a rock mass characterised by a random conductivity field is first considered. A Monte Carlo approach is used to investigate the existence and structure of continuous high conductivity paths within low conductivity media. The rock mass is modelled as a grid of cubic elements. For all grids it was possible to identify at least one path along which hydraulic conductivity was everywhere greater than effective conductivity of the medium. The influence of these extreme paths on fluid flow, measured permeability and preferred transport of solutes is yet to be fully examined. 893129 Improvement to the one-step outflow method for the determination of soil water diffusivities Valiantzas, J D; Kerkides, P G; Poulovassilis, A Water Resour Res V24. N I l , Nov 1988, P1911-1920 The outflow method is commonly used to determine the relation between soil water diffusivity and volumetric water content on undisturbed soil cores. An improved, quick, and reliable iterative method of analysis of one step outflow tests is presented. It gives better results than other analyses even in cases where there is extreme nonlinearity in the relation or when it is not monotonous. The method has been validated against real and simulated outflow test data. 893130 Interpretation of field tracer tests of a single fracture using a transient solute storage model Raven, K G: Novakowski, K S; Lapcevic, P A Water Resour Res V24, N12, Dec 1988, P2019-2032 Results and interpretation of five induced gradient tracer tests carried out at five different interborehole fluid velocities in a single fracture in monzonitic gneiss are presented. The experiments were performed over interhole distances of 12.7-29.8m, between straddle packers isolating the fracture in three boreholes. An application of the transient solute storage model to analyse the results is shown. In addition, the concept of initial advective dominated flow transformed to Fickian type behaviour with increasing transport time is evaluated. It is indicated that these experiments may underestimate dispersion characteristics of single fractures under natural flow conditions.
1989 Pergamon Press plc. Reproduction not permitted
A mathematical description of the G R F model and equations relating to common hydraulic tests are presented. Conceptual problems of the model and problems in relating it to field data are discussed. 893127 Discrimination among one-dimensional models of solute transport in porous media: implications for sampling design Knopman, D S; Voss, C I Water Resour Res V24, N I l . Not' 1988, P1859-1876 Solute transport models require specification of field scale parameters, which may not be easy to obtain, and direct verification is difficult. Comparison of performance of one model with another, model discrimination,where observations from designed sampling rounds are used to test hypotheses, is often more practical. Two variables in model discrimination are addressed, effects of solute concentration on transport and optimisation of sampling strategy. Specific examples of model error are examined, and sampling designs proposed. 893128 Stochastic analysis of paths of high hydraulic conductivity in porous media Silliman, S E; Wright, A L Water Resour Res V24. N i l . Noe 1988. P1901-1910 Representation of a single, nonrandom "effective' conductivity for a rock mass characterised by a random conductivity field is first considered. A Monte Carlo approach is used to investigate the existence and structure of continuous high conductivity paths within low conductivity media. The rock mass is modelled as a grid of cubic elements. For all grids it was possible to identify at least one path along which hydraulic conductivity was everywhere greater than effective conductivity of the medium. The influence of these extreme paths on fluid flow, measured permeability and preferred transport of solutes is yet to be fully examined. 893129 Improvement to the one-step outflow method for the determination of soil water diffusivities Valiantzas, J D; Kerkides, P G; Poulovassilis, A Water Resour Res V24. N I l , Nov 1988, P1911-1920 The outflow method is commonly used to determine the relation between soil water diffusivity and volumetric water content on undisturbed soil cores. An improved, quick, and reliable iterative method of analysis of one step outflow tests is presented. It gives better results than other analyses even in cases where there is extreme nonlinearity in the relation or when it is not monotonous. The method has been validated against real and simulated outflow test data. 893130 Interpretation of field tracer tests of a single fracture using a transient solute storage model Raven, K G: Novakowski, K S; Lapcevic, P A Water Resour Res V24, N12, Dec 1988, P2019-2032 Results and interpretation of five induced gradient tracer tests carried out at five different interborehole fluid velocities in a single fracture in monzonitic gneiss are presented. The experiments were performed over interhole distances of 12.7-29.8m, between straddle packers isolating the fracture in three boreholes. An application of the transient solute storage model to analyse the results is shown. In addition, the concept of initial advective dominated flow transformed to Fickian type behaviour with increasing transport time is evaluated. It is indicated that these experiments may underestimate dispersion characteristics of single fractures under natural flow conditions.
1989 Pergamon Press plc. Reproduction not permitted