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244 results on '"Müller, Tobias M."'

15. Introduction

Author

Ba, Jing, primary, Du, Qizhen, additional, Carcione, José M., additional, Zhang, Houzhu (James), additional, and Müller, Tobias M., additional

Published
2015
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16. List of Contributors

Author

Ba, Jing, primary, Bai, Xuming, additional, Carcione, José M., additional, Caspari, Eva, additional, Du, Qizhen, additional, Fang, Gang, additional, Gong, Xufei, additional, Guo, Yuqian, additional, Gurevich, Boris, additional, He, Xinzhen, additional, Lebedev, Maxim, additional, Li, Jinsong, additional, Lopes, Sofia, additional, Müller, Tobias M., additional, Qi, Qiaomu, additional, Rubino, J. Germán, additional, Sun, Weitao, additional, Velis, Danilo, additional, Yan, Xinfei, additional, Yu, Hao, additional, Yuan, Zhenyu, additional, Zhang, Houzhu (James), additional, Zhang, Lin, additional, Zhang, Mingqiang, additional, Zhang, Xingyang, additional, and Zhao, Xianzheng, additional

Published
2015
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43. Effect of porosity gradient on the permeability tensor.

Author

Madadi, Mahyar and Müller, Tobias M.

Subjects
*PERMEABILITY, *POROSITY, *POROUS materials, *DRAG force, *ROCK permeability
Abstract

Experimental investigations often reveal that there is a correlation between porosity and permeability in rocks. The most commonly used model to predict the porosity–permeability relation is due to Kozeny–Carman or its many modifications. However, these models are problematic because they always involve an empirical constant and, in macroscopically heterogeneous porous media with non‐uniform porosity, more than one empirical constant would be required. Moreover, the tensor character of the permeability is not accounted for when the permeability is conceptualized as a plain function of the porosity. To overcome these limitations, we devise an approach by analysing the drag force in the volume averaging framework of poroelasticity. This allows us to deduce an expression for the inverse permeability tensor. It is the sum of the inverse of the permeability pertaining to a representative volume element and the second spatial derivative of porosity. Therefore, the gradient of porosity changes the permeability depending on the variations of macroscopic porosity variations. This result is thought to be relevant in applications where porosity maps are converted into permeability maps. [ABSTRACT FROM AUTHOR]

Published
2021
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44. Modeling Forced Imbibition Processes and the Associated Seismic Attenuation in Heterogeneous Porous Rocks

Author

Solazzi, Santiago G., Guarracino, Luis, Rubino, J. Germán, Müller, Tobias M., and Holliger, Klaus

Subjects
Soil science, Compressibility, Imbibition, SEISMIC ATTENUATION, Attenuation, Geology, Geofísica, Seismic wave, Crust, COMPUTATIONAL SEISMOLOGY, Ciencias de la Tierra y relacionadas con el Medio Ambiente, Geotechnical engineering, Fluid dynamics, THEORETICAL SEISMOLOGY, ACOUSTIC PROPERTIES, Meteorología y Ciencias Atmosféricas, Anelastic attenuation factor, CIENCIAS NATURALES Y EXACTAS, Saturation (chemistry)
Abstract

Quantifying seismic attenuation during laboratory imbibition experiments can provide useful information towards the use of seismic waves for monitoring injection and extraction of fluids in the Earth's crust. However, a deeper understanding of the physical causes producing the observed attenuation is needed for this purpose. In this work, we analyze seismic attenuation due to mesoscopic wave-induced fluid flow (WIFF) produced by realistic fluid distributions representative of imbibition experiments. To do so, we first perform two-phase flow simulations in a heterogeneous rock sample to emulate a forced imbibition experiment. We then select a sub-sample of the considered rock containing the resulting time-dependent saturation fields, and apply a numerical upscaling procedure to compute the associated seismic attenuation. By exploring both saturation distributions and seismic attenuation we observe that two manifestations of WIFF arise during imbibition experiments: the first one is produced by the compressibility contrast associated with the saturation front, whereas the second one is due to the presence of patches containing very high amounts of water that are located behind the saturation front. We demonstrate that while the former process is expected to play a significant role in the case of high injection rates, which are associated with viscous-dominated imbibition processes, the latter becomes predominant during capillary-dominated processes, that is, for relatively low injection rates. We conclude that this kind of joint numerical analysis constitutes a useful tool for improving our understanding of the physical mechanisms producing seismic attenuation during laboratory imbibition experiments., Facultad de Ciencias Astronómicas y Geofísicas

Published
2017

48. Seismic attenuation: effects of interfacial impedance on wave-induced pressure diffusion

Author

Qi, Qiaomu, Müller, Tobias M., Rubino, J. Germán, Qi, Qiaomu, Müller, Tobias M., and Rubino, J. Germán

Abstract

Seismic attenuation and dispersion in layered sedimentary structures are often interpreted in terms of the classical White model for wave-induced pressure diffusion across the layers. However, this interlayer flow is severely dependent on the properties of the interface separating two layers. This interface behaviour can be described by a pressure jump boundary condition involving a non-vanishing interfacial impedance. In this paper, we incorporate the interfacial impedance into the White model by solving a boundary value problem in the framework of quasi-static poroelasticity. We show that the White model predictions for attenuation and dispersion substantially change. These changes can be attributed to petrophysically plausible scenarios such as imperfect hydraulic contacts or the presence of capillarity

Published
2017

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