Tiziana Vanorio | Stanford University (original) (raw)
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Papers by Tiziana Vanorio
SEG Technical Program Expanded Abstracts 2011, 2011
Egs General Assembly Conference Abstracts, 2002
Understanding and modeling ground deformation mechanisms in volcanic areas can allow for a more i... more Understanding and modeling ground deformation mechanisms in volcanic areas can allow for a more informed assessment of eruptive activity. Tools that can improve constraining of these models will help to make better predictions and thus minimize volcanic hazards. Our contribution to studying ground deformation in Campi Flegrei (CF) volcanic area (Italy) consisted of a cross-disciplinary methodology that com- bined rock physics properties, well logs, and field observation data. Using a pressure buildup mechanism as an example of the cause of ground deformation, we show how quantitative assessment of ground deformation can be constrained by rock physics. Analysis of site-relevant rocks defined ranges of rock physics properties under differ- ent environment conditions of stress, depth, and pore fluid pressure. We used these site-relevant experimental velocity-pressure data to compute parameters such as pore stiffness, Skempton's coefficient, and the hydraulic diffusion coefficient that are in- volved in ground deformation computations based on stress-induced interstitial fluid pressure in porous media. This paper emphasizes that assessment of pore stiffness, which crucially depends on pore shape, is necessary in ground deformation models based on hypotheses of pore pressure generation. Computations that use low pore stiffnesses (e.g. penny-shaped cracks) provide pore pressure higher than computations using high pore stiffnesses (e.g. spherical pores). Thus, induced pore pressures driv- ing vertical displacements can be achieved at lower stresses in porous media with low pore stiffness than in rocks with higher pore stiffness. We show that permeability vari- ations as a function of pore fluid pressure and overpressure detection studies for the CF area are critical in modeling deformation mechanism where permeability reduction by crack healing and mineral precipitation might be responsible for the pore pressure buildup.
Egs General Assembly Conference Abstracts, 2002
We present ultrasonic P- and S-waves velocity measurements on pure clay samples us- ing three dif... more We present ultrasonic P- and S-waves velocity measurements on pure clay samples us- ing three different experiment setups. These experiments provided petrophysical and acoustic properties of clay minerals as a function both of mineralogy and compaction. In the first experiment, acoustic measurements were performed on cold-pressed clay aggregates at ambient and at hydrostatic pressure conditions. Porosity and grain den- sity values of the different clay mineralogy aggregates ranged from 4 to 43% and 2.13 to 2.83 g cm-3, respectively. In the second experiment, we measured P-wave velocity and attenuation in a kaolinite-water suspension in which clay concentration was in- creased up to 60%. In the third experiment, P- and S- wave velocities were measured during uniaxial stress compaction of clay powders. Results from all three experiments revealed low bulk (K) and shear (µ) moduli for kaolinite, montmorillonite, and smec- tite; the values range between 6-12 GPa for K and 4-6 GPa for µ, respectively. Using these clay moduli values in effective medium and granular porous media (theories) models, velocity is predicted in saturated pure kaolinite samples, kaolinite suspension and shaly sandstone fairly well. Experimental results also showed that water interlay- ers play an important role in the compaction and strength of clay aggregates. Clay minerals carrying on water interlayers in their structure showed high compaction and strength. This study is relevant for a more reliable assessment of the seismic response in reservoirs and/or basins characterized by clay-bearing formations.
![Research paper thumbnail of The rock physics basis for 4D seismic monitoring of CO[sub 2] fate: Are we there yet?](https://attachments.academia-assets.com/43869057/thumbnails/1.jpg)
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Fluid movement in geologic formations is often monitored using seismic methods with relations (e.... more Fluid movement in geologic formations is often monitored using seismic methods with relations (e.g., Gassmann fluid substitution and effective stress) providing the basis for quantitatively interpreting subsurface fluid saturation and state from seismic data. Nearly all commonly used relations assume that the fluid introduced modifies neither the rock matrix nor its microstructure. Depending on the rock, introduction of a fluid
The flow of a reactive fluid through a porous medium involves both transport and reaction mechani... more The flow of a reactive fluid through a porous medium involves both transport and reaction mechanisms that are strongly coupled. Several chemical processes can occur, such as dissolution, precipitation and/or formation of new mineralogical phases which modify both the chemical and physical properties of the porous network. These mechanisms may ultimately affect the macroscopic rock properties such as permeability, electrical
Gassmann's model is commonly used to predict how changes in pore fluids affect in-situ seismi... more Gassmann's model is commonly used to predict how changes in pore fluids affect in-situ seismic velocities. Although Gassmann's model is generally successful in medium to high porosity sandstones, its appropriateness for quantifying fluid effects in carbonate rocks is questioned in literature. Questions rice from the model assumptions which, very likely oversimplify the complex rock-fluid interaction in carbonates. Critical issues include
Pure and Applied Geophysics, 1999
--This paper illustrates the laboratory procedures and experiments carried out on samples with di... more --This paper illustrates the laboratory procedures and experiments carried out on samples with different lithologies and reconstructed samples in order to test and implement an electroseismic model (Carrara et al., 1994) which allows the evaluation of porosity and the saturation degree of rocks. The testing was conducted by comparing porosity (&#124) and saturation degree (Sw&#118) values, obtained from measured resistivity
Reservoir Characterization and Production Monitoring, 2010
SEG Technical Program Expanded Abstracts 2007, 2007
SEG Technical Program Expanded Abstracts 2009, 2009
SEG Technical Program Expanded Abstracts 2009, 2009
... 255. Faust, LY, 1953, A velocity function including lithologic variation: Geophysics, 18, 271... more ... 255. Faust, LY, 1953, A velocity function including lithologic variation: Geophysics, 18, 271–288. Gal, D., J. Dvorkin, and A. Nur, 1998, A physical model for porosity reduction in sandstones: Geophysics, 63, 454–459. Gassmann ...
SEG Technical Program Expanded Abstracts 2010, 2010
SEG Technical Program Expanded Abstracts 2011, 2011
Egs General Assembly Conference Abstracts, 2002
Understanding and modeling ground deformation mechanisms in volcanic areas can allow for a more i... more Understanding and modeling ground deformation mechanisms in volcanic areas can allow for a more informed assessment of eruptive activity. Tools that can improve constraining of these models will help to make better predictions and thus minimize volcanic hazards. Our contribution to studying ground deformation in Campi Flegrei (CF) volcanic area (Italy) consisted of a cross-disciplinary methodology that com- bined rock physics properties, well logs, and field observation data. Using a pressure buildup mechanism as an example of the cause of ground deformation, we show how quantitative assessment of ground deformation can be constrained by rock physics. Analysis of site-relevant rocks defined ranges of rock physics properties under differ- ent environment conditions of stress, depth, and pore fluid pressure. We used these site-relevant experimental velocity-pressure data to compute parameters such as pore stiffness, Skempton's coefficient, and the hydraulic diffusion coefficient that are in- volved in ground deformation computations based on stress-induced interstitial fluid pressure in porous media. This paper emphasizes that assessment of pore stiffness, which crucially depends on pore shape, is necessary in ground deformation models based on hypotheses of pore pressure generation. Computations that use low pore stiffnesses (e.g. penny-shaped cracks) provide pore pressure higher than computations using high pore stiffnesses (e.g. spherical pores). Thus, induced pore pressures driv- ing vertical displacements can be achieved at lower stresses in porous media with low pore stiffness than in rocks with higher pore stiffness. We show that permeability vari- ations as a function of pore fluid pressure and overpressure detection studies for the CF area are critical in modeling deformation mechanism where permeability reduction by crack healing and mineral precipitation might be responsible for the pore pressure buildup.
Egs General Assembly Conference Abstracts, 2002
We present ultrasonic P- and S-waves velocity measurements on pure clay samples us- ing three dif... more We present ultrasonic P- and S-waves velocity measurements on pure clay samples us- ing three different experiment setups. These experiments provided petrophysical and acoustic properties of clay minerals as a function both of mineralogy and compaction. In the first experiment, acoustic measurements were performed on cold-pressed clay aggregates at ambient and at hydrostatic pressure conditions. Porosity and grain den- sity values of the different clay mineralogy aggregates ranged from 4 to 43% and 2.13 to 2.83 g cm-3, respectively. In the second experiment, we measured P-wave velocity and attenuation in a kaolinite-water suspension in which clay concentration was in- creased up to 60%. In the third experiment, P- and S- wave velocities were measured during uniaxial stress compaction of clay powders. Results from all three experiments revealed low bulk (K) and shear (µ) moduli for kaolinite, montmorillonite, and smec- tite; the values range between 6-12 GPa for K and 4-6 GPa for µ, respectively. Using these clay moduli values in effective medium and granular porous media (theories) models, velocity is predicted in saturated pure kaolinite samples, kaolinite suspension and shaly sandstone fairly well. Experimental results also showed that water interlay- ers play an important role in the compaction and strength of clay aggregates. Clay minerals carrying on water interlayers in their structure showed high compaction and strength. This study is relevant for a more reliable assessment of the seismic response in reservoirs and/or basins characterized by clay-bearing formations.
Fluid movement in geologic formations is often monitored using seismic methods with relations (e.... more Fluid movement in geologic formations is often monitored using seismic methods with relations (e.g., Gassmann fluid substitution and effective stress) providing the basis for quantitatively interpreting subsurface fluid saturation and state from seismic data. Nearly all commonly used relations assume that the fluid introduced modifies neither the rock matrix nor its microstructure. Depending on the rock, introduction of a fluid
The flow of a reactive fluid through a porous medium involves both transport and reaction mechani... more The flow of a reactive fluid through a porous medium involves both transport and reaction mechanisms that are strongly coupled. Several chemical processes can occur, such as dissolution, precipitation and/or formation of new mineralogical phases which modify both the chemical and physical properties of the porous network. These mechanisms may ultimately affect the macroscopic rock properties such as permeability, electrical
Gassmann's model is commonly used to predict how changes in pore fluids affect in-situ seismi... more Gassmann's model is commonly used to predict how changes in pore fluids affect in-situ seismic velocities. Although Gassmann's model is generally successful in medium to high porosity sandstones, its appropriateness for quantifying fluid effects in carbonate rocks is questioned in literature. Questions rice from the model assumptions which, very likely oversimplify the complex rock-fluid interaction in carbonates. Critical issues include
Pure and Applied Geophysics, 1999
--This paper illustrates the laboratory procedures and experiments carried out on samples with di... more --This paper illustrates the laboratory procedures and experiments carried out on samples with different lithologies and reconstructed samples in order to test and implement an electroseismic model (Carrara et al., 1994) which allows the evaluation of porosity and the saturation degree of rocks. The testing was conducted by comparing porosity (&#124) and saturation degree (Sw&#118) values, obtained from measured resistivity
Reservoir Characterization and Production Monitoring, 2010
SEG Technical Program Expanded Abstracts 2007, 2007
SEG Technical Program Expanded Abstracts 2009, 2009
SEG Technical Program Expanded Abstracts 2009, 2009
... 255. Faust, LY, 1953, A velocity function including lithologic variation: Geophysics, 18, 271... more ... 255. Faust, LY, 1953, A velocity function including lithologic variation: Geophysics, 18, 271–288. Gal, D., J. Dvorkin, and A. Nur, 1998, A physical model for porosity reduction in sandstones: Geophysics, 63, 454–459. Gassmann ...
SEG Technical Program Expanded Abstracts 2010, 2010