Searched for: author%3A%22Minato%2C+S.%22
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Kawasaki, Y. (author), Minato, S. (author), Ghose, R. (author)
Bulk-density ( ρ) of soil is an important indicator of soil compaction and type. A knowledge of the spatial variability of in situ soil density is important in geotechnical engineering, hydrology and agriculture. Surface geophysical methods have so far shown limited success in providing an accurate and high-resolution image of 3-D soil...
journal article 2023
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Minato, S. (author), Ghose, R. (author)
When using waveform tomography to perform high-resolution imaging of a medium, it is vital to calculate the sensitivity in order to describe how well a model fits a given set of data and how the sensitivity changes with the spatial distribution of the heterogeneities. The traditional principle behind calculating the sensitivity—for detecting...
journal article 2021
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Hunziker, Jörg (author), Greenwood, Andrew (author), Minato, S. (author), Barbosa, Nicolás Daniel (author), Caspari, Eva (author), Holliger, Klaus (author)
<p>The hydraulic and mechanical characterization of fractures is crucial for a wide range of pertinent applications, such as geothermal energy production, hydrocarbon exploration, &lt;span classCombining double low line"inline-formula"&gt;CO2&lt;/span&gt; sequestration, and nuclear waste disposal. Direct hydraulic and mechanical testing of...
journal article 2020
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Minato, S. (author), Wapenaar, C.P.A. (author), Ghose, R. (author)
To quantitatively image fractures with high resolution, we have developed an elastic least-squares migration (LSM) algorithm coupled with linear-slip theory, which accurately addresses seismic wave interaction with thin structures. We derive a linearized waveform inversion using the Born approximation to the boundary integral equation for...
journal article 2020
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Minato, S. (author), Ghose, R. (author), Wapenaar, C.P.A. (author)
Single-well reflection imaging using sonic logging data successfully locates fine-scale structures around a borehole including fractures. In order to achieve accurate and quantitative estimation of fracture properties with high resolution, we propose to couple least-squares migration with linear slip theory. The proposed least-squares...
conference paper 2019
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Minato, S. (author), Ghose, R. (author), Wapenaar, C.P.A. (author)
Characterizing the mechanical and hydraulic properties of fractures is crucial in hydrocarbon and geothermal field development. Contrary to passive microseismic measurements, active seismic measurements using a borehole, e.g., VSP or sonic logging, have a potential to address aseismic fractures. However, there is a considerable scale gap between...
conference paper 2019
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Minato, S. (author), Ghose, R. (author), Wapenaar, C.P.A. (author)
Characterizing subsurface fractures is a key to developing hydrocarbon and geothermal fields, as well as providing fundamental information on fracture system relevant to regional seismotectonics. Seismic characterization of fractures has generally been based on the effective medium theory, which considers seismically invisible small fractures....
conference paper 2019
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Minato, S. (author), Ghose, R. (author)
Time-lapse seismics has a wide range of application in different scales, from near-surface to resource exploration. Crosshole seismics is used to characterize fluid reservoirs and to obtain highly resolved rock/soil-dynamic parameters e.g., elastic moduli and Poisson ratio. Developments in distributed acoustic sensing shows the potential of...
conference paper 2019
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Minato, S. (author), Ghose, R. (author)
Crosswell seismic measurements enable obtaining high resolution, high accuracy images of the subsurface between boreholes. They are, however, generally expensive considering the need of deployment of special downhole sources. In this study, we develop a novel nonlinear waveform inversion to estimate velocity structures between two vertical...
conference paper 2019
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Suzaki, A. (author), Minato, S. (author), Ghose, R. (author), Konishi, Chisato (author), Sakai, Naoki (author)
journal article 2017
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Minato, S. (author), Ghose, R. (author)
Low-frequency, axially-symmetric guided waves which propagate along a fluid-filled borehole (tube waves) are studied in order to characterize the hydraulic fractures intersecting the borehole. We formulate a new equation for the total tube wavefield, which includes simultaneous effects of (1) tube-wave scattering (reflection and transmission)...
journal article 2017
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Minato, S. (author), Ghose, R. (author)
The hydraulic properties of subsurface fractures are critically important in the exploration of geothermal and hydrocarbon reservoirs. The analysis of tube waves (low-frequency Stoneley waves propagating along a fluidfilled borehole) is a promising approach to estimate the hydraulic properties of fractures intersecting a borehole. We present a...
conference paper 2017
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Suzaki, A. (author), Ghose, R. (author), Minato, S. (author)
Understanding the effect of saturation is important in assessing the failure mechanism on the land-side of a river-dyke due to rising water level in a river after heavy rainfall. S-wave velocity is controlled by soil suction and degree of saturation. Therefore, there is a possibility to estimate the unsaturated soil properties from the temporal...
conference paper 2017
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Minato, S. (author), Ghose, R. (author), Osukuku, G. (author)
Characterizing fracture is important in order to understand how groundwater is transported and stored in fractured environments, to assess contaminant transport through fractures, as well to evaluate the mechanical behaviour of a fractured rock mass. In this research, we have investigated through careful laboratory experiments the amplitude...
conference paper 2017
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Minato, S. (author), Ghose, R. (author), Tsuji, Takeshi (author), Ikeda, Michiharu (author), Onishi, Kozo (author)
Fluid-filled fractures and fissures often determine the pathways and volume of fluid movement. They are critically important in crustal seismology and in the exploration of geothermal and hydrocarbon reservoirs. We introduce a model for tube-wave scattering and generation at dipping, parallel-wall fractures intersecting a fluid-filled borehole....
journal article 2017
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Minato, S. (author), Ghose, R. (author), Osukuku, Godfred (author)
<br/>The elastic compliance of a fracture can be spatially varying, reflecting the variation of microscale properties of the fracture, e.g., aperture, contact asperities, and fracture infill. Characterizing the spatial heterogeneity of a fracture is crucial in explaining the apparent frequency dependence of fracture compliance and in addressing...
journal article 2017
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Nishitsuji, Y. (author), Minato, S. (author), Boullenger, B. (author), Gomez, M (author), Wapenaar, C.P.A. (author), Draganov, D.S. (author)
We have developed an application of passive seismic interferometry (SI) using P-wave coda of local earthquakes for the purpose of crustal-scale reflection imaging. We processed the reflection gathers retrieved from SI following a standard seismic processing in exploration seismology. We applied SI to the P-wave coda using crosscorrelation,...
journal article 2016
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Minato, S. (author), Ghose, R. (author)
The spatial heterogeneity along a fracture is a key determinant for fracture-associated mechanical and hydraulic properties of the subsurface. Laboratory experiments have been performed to test the applicability of the nonwelded interface representation to predict the frequency- and angle-dependent elastic response of a single fracture. The...
journal article 2016
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Minato, S. (author), Ghose, R. (author)
Though well known for layer boundaries, the use of amplitude-versus-offset (AVO) variations for non-welded boundaries like fractures is not yet investigated. Depending on the seismic wavelength used, fractures can be regarded as thin, compliant zones in rocks, in different scales. We explore the potential of multiangle AVO inversion of P-P and P...
journal article 2016
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Minato, S. (author), Ghose, R. (author)
We explore the potential of multi-angle AVO inversion of P-P and P-S reflections from a fracture to estimate fracture proper- ties. Although AVO analysis of welded interface like geologi- cal layer boundaries is common, the use of AVO variations for nonwelded boundaries like fractures is yet to be investigated. We conduct laboratory experiments...
conference paper 2016
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