Kenichi Ando - Academia.edu (original) (raw)

Papers by Kenichi Ando

Stochastic continuum modeling of flow and transport was conducted for a fractured crystalline roc... more Stochastic continuum modeling of flow and transport was conducted for a fractured crystalline rock mass at Fanay-Augeres in France. Two dimensional models were used in conjunction with hydraulic conductivity, piezometric head, and tracer test data. The boundary conditions were established by ordinary kriging. One hundred realizations of hydraulic conductivity were generated conditionally by sequential indicator simulation, and flow was computed numerically for each realization. One realization that gave the beast fit to measured flow rate into the experimental drift at the site, and to measured head data, was selected for the analysis of transport. Porosity and dispersivity values were determined by calibration against selected tracer test data. The calibrated model was then validated by successfully predicting the peak arrival time as well as 50% and 25% breakthrough durations of other tracers. We conclude that the continuum stochastic approach is well suited for the interpretation...

Journal of the Society of Materials Science, Japan, 2012

Survey methods using elastic wave velocity have been performed in order to estimate the pore flui... more Survey methods using elastic wave velocity have been performed in order to estimate the pore fluid properties in rock mass, but the viscosity and density of pore fluid have not been estimated quantitatively by the values of velocity or the velocity changes. We describe in this paper whether pore fluid properties can be estimated by using the dispersion of longitudinal elastic waves. We measured the frequency-dependent velocity data of longitudinal elastic waves in porous specimens and the dependence of the velocity dispersion on the kinematic viscosity of pore fluid. Moreover, we try to explain the velocity dispersion shown by the measurement data using the Biot theory. The Biot theory explains that the dispersion phenomenon is caused by the elastic property change in the media with the interaction between the solid phase and liquid phase, so the dispersion is dependent on the properties of liquid phase. The measurement data showed the phase velocities of longitudinal waves increased with an increase of frequencies and the characteristic frequencies which indicate the points of inflection moved to higher frequencies with an increase of kinematic viscosities of pore fluid. We report that we can estimate the kinematic viscosity of pore fluid in rock mass by using the dispersion curves which graphed the relation between the phase velocities and frequencies.

Hydrogeology Journal, 2003

R (1990b) Modelling fracture flow with a stochastic discrete fracture network: calibration and va... more R (1990b) Modelling fracture flow with a stochastic discrete fracture network: calibration and validation. 2. The transport model. Water Resour Res 26(3):491-500 c Neuman SP (1987) Stochastic continuum representation of fractured rock permeability as an alternative to the REV and fracture network concepts, in Rock Mechanics. In: Farmer IW, Daemen JJK, Desai CS, Glass CE, Neuman SP (eds) Proceedings of the 28th U.S. Symposium, Tucson, Arizona. Balkema, Rotterdam, pp 533-561 d Neuman SP (1988) A proposed conceptual framework and methodology for investigating flow and transport in Swedish crystalline rocks.

Water Resources Research, 2012

The accurate characterization of fractured geologic medium, imaging of fracture patterns and thei... more The accurate characterization of fractured geologic medium, imaging of fracture patterns and their connectivity have been a challenge for decades. Recently, hydraulic tomography has been proposed as a new method for imaging the hydraulic conductivity (K) and specific storage (S s) distributions of fractured geologic media. While encouraging results have been obtained in the field, the method has not been rigorously assessed in a controlled laboratory setting. In this study, we assess the performance of transient hydraulic tomography (THT) in a fractured dolomitic rock block. The block is characterized through flow-through tests and multiple pumping tests. The pumping test data were then analyzed with the THT code of Zhu and Yeh (2005) to image the fracture patterns and their connectivity through the delineation of K and S s distributions (or tomograms). Results show that the THT analysis of pumping tests yields high-K and lowS s zones that capture the fracture pattern and their connectivity quite well and those patterns become more vivid as additional pumping test data are added to the inverse model. The performance of the estimated K and S s tomograms are then assessed by: (1) comparing the tomograms obtained from synthetic to real data; (2) comparing the tomograms from two different pumping configurations; (3) comparing the estimated geometric mean of the hydraulic conductivity (K G) from the K tomogram to the effective hydraulic conductivity (K eff) estimated from the flow-through tests; and (4) predicting five independent pumping tests not used in the construction of the K and S s tomograms. The performance assessment of the K and S s tomograms reveals that THT is able to image high-K and lowS s zones that correspond to fracture locations in the fractured rock block and that the tomograms can be used to predict drawdowns from pumping tests not used in the construction of the tomograms with reasonable fidelity.

Water Resources Research, 2009

Ground Water, 2008

Fracture zones and their connectivity in geologic media are of great importance to ground water r... more Fracture zones and their connectivity in geologic media are of great importance to ground water resources management as well as ground water contamination prevention and remediation. In this paper, we applied a recently developed hydraulic tomography (HT) technique and an analysis algorithm (sequential successive linear estimator) to synthetic fractured media. The application aims to explore the potential utility of the technique and the algorithm for characterizing fracture zone distribution and their connectivity. Results of this investigation showed that using HT with a limited number of wells, the fracture zone distribution and its connectivity (general pattern) can be mapped satisfactorily although estimated hydraulic property fields are smooth. As the number of wells and monitoring ports increases, the fracture zone distribution and connectivity become vivid and the estimated hydraulic properties approach true values. We hope that the success of this application may promote the development and application of the new generations of technology (i.e., hydraulic, tracer, pneumatic tomographic surveys) for mapping fractures and other features in geologic media.

Stochastic continuum modeling of flow and transport was conducted for a fractured crystalline roc... more Stochastic continuum modeling of flow and transport was conducted for a fractured crystalline rock mass at Fanay-Augeres in France. Two dimensional models were used in conjunction with hydraulic conductivity, piezometric head, and tracer test data. The boundary conditions were established by ordinary kriging. One hundred realizations of hydraulic conductivity were generated conditionally by sequential indicator simulation, and flow was computed numerically for each realization. One realization that gave the beast fit to measured flow rate into the experimental drift at the site, and to measured head data, was selected for the analysis of transport. Porosity and dispersivity values were determined by calibration against selected tracer test data. The calibrated model was then validated by successfully predicting the peak arrival time as well as 50% and 25% breakthrough durations of other tracers. We conclude that the continuum stochastic approach is well suited for the interpretation...

Journal of the Society of Materials Science, Japan, 2012

Survey methods using elastic wave velocity have been performed in order to estimate the pore flui... more Survey methods using elastic wave velocity have been performed in order to estimate the pore fluid properties in rock mass, but the viscosity and density of pore fluid have not been estimated quantitatively by the values of velocity or the velocity changes. We describe in this paper whether pore fluid properties can be estimated by using the dispersion of longitudinal elastic waves. We measured the frequency-dependent velocity data of longitudinal elastic waves in porous specimens and the dependence of the velocity dispersion on the kinematic viscosity of pore fluid. Moreover, we try to explain the velocity dispersion shown by the measurement data using the Biot theory. The Biot theory explains that the dispersion phenomenon is caused by the elastic property change in the media with the interaction between the solid phase and liquid phase, so the dispersion is dependent on the properties of liquid phase. The measurement data showed the phase velocities of longitudinal waves increased with an increase of frequencies and the characteristic frequencies which indicate the points of inflection moved to higher frequencies with an increase of kinematic viscosities of pore fluid. We report that we can estimate the kinematic viscosity of pore fluid in rock mass by using the dispersion curves which graphed the relation between the phase velocities and frequencies.

Hydrogeology Journal, 2003

R (1990b) Modelling fracture flow with a stochastic discrete fracture network: calibration and va... more R (1990b) Modelling fracture flow with a stochastic discrete fracture network: calibration and validation. 2. The transport model. Water Resour Res 26(3):491-500 c Neuman SP (1987) Stochastic continuum representation of fractured rock permeability as an alternative to the REV and fracture network concepts, in Rock Mechanics. In: Farmer IW, Daemen JJK, Desai CS, Glass CE, Neuman SP (eds) Proceedings of the 28th U.S. Symposium, Tucson, Arizona. Balkema, Rotterdam, pp 533-561 d Neuman SP (1988) A proposed conceptual framework and methodology for investigating flow and transport in Swedish crystalline rocks.

Water Resources Research, 2012

The accurate characterization of fractured geologic medium, imaging of fracture patterns and thei... more The accurate characterization of fractured geologic medium, imaging of fracture patterns and their connectivity have been a challenge for decades. Recently, hydraulic tomography has been proposed as a new method for imaging the hydraulic conductivity (K) and specific storage (S s) distributions of fractured geologic media. While encouraging results have been obtained in the field, the method has not been rigorously assessed in a controlled laboratory setting. In this study, we assess the performance of transient hydraulic tomography (THT) in a fractured dolomitic rock block. The block is characterized through flow-through tests and multiple pumping tests. The pumping test data were then analyzed with the THT code of Zhu and Yeh (2005) to image the fracture patterns and their connectivity through the delineation of K and S s distributions (or tomograms). Results show that the THT analysis of pumping tests yields high-K and lowS s zones that capture the fracture pattern and their connectivity quite well and those patterns become more vivid as additional pumping test data are added to the inverse model. The performance of the estimated K and S s tomograms are then assessed by: (1) comparing the tomograms obtained from synthetic to real data; (2) comparing the tomograms from two different pumping configurations; (3) comparing the estimated geometric mean of the hydraulic conductivity (K G) from the K tomogram to the effective hydraulic conductivity (K eff) estimated from the flow-through tests; and (4) predicting five independent pumping tests not used in the construction of the K and S s tomograms. The performance assessment of the K and S s tomograms reveals that THT is able to image high-K and lowS s zones that correspond to fracture locations in the fractured rock block and that the tomograms can be used to predict drawdowns from pumping tests not used in the construction of the tomograms with reasonable fidelity.

Water Resources Research, 2009

Ground Water, 2008

Fracture zones and their connectivity in geologic media are of great importance to ground water r... more Fracture zones and their connectivity in geologic media are of great importance to ground water resources management as well as ground water contamination prevention and remediation. In this paper, we applied a recently developed hydraulic tomography (HT) technique and an analysis algorithm (sequential successive linear estimator) to synthetic fractured media. The application aims to explore the potential utility of the technique and the algorithm for characterizing fracture zone distribution and their connectivity. Results of this investigation showed that using HT with a limited number of wells, the fracture zone distribution and its connectivity (general pattern) can be mapped satisfactorily although estimated hydraulic property fields are smooth. As the number of wells and monitoring ports increases, the fracture zone distribution and connectivity become vivid and the estimated hydraulic properties approach true values. We hope that the success of this application may promote the development and application of the new generations of technology (i.e., hydraulic, tracer, pneumatic tomographic surveys) for mapping fractures and other features in geologic media.