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SUMMARY:About the hydro-mechanics of fractures and fracture networks in ro
 cks
DTSTART:20170512T121500
DTEND:20170512T131500
DTSTAMP:20260916T014031Z
UID:a1e92895932e56b1bf68ddb46d40f9160d2be2481fc2fe81d09a8df3
CATEGORIES:Conferences - Seminars
DESCRIPTION:Prof. Dr.-Ing. Holger Steeb\, Professor (W3) at Faculty of Civ
 il and Environmental Engineering\, Institute of Applied Mechanics (CE)\, D
 ept of Continuum Mechanics\, University of Stuttgart\, Germany\nA comprehe
 nsive understanding of the physical properties of seismic waves (like disp
 ersive phase velocities and/or attenuation) in fractured porous rocks is i
 mportant in various fields like hydrocarbon and geothermal exploration/exp
 loitation or water reservoir management. E.g. characterization of subsurfa
 ce fluid flow requires accounting for hydromechanical coupling between flu
 id-pressure variations in conduits and related rock deformation.\nIn this 
 presentation\, modeling aspects and numerical simulations of a (weakly) co
 mpressible fluid along compliant hydraulic conduits\, such as joints or fr
 actures/fracture networks\, are investigated. In order to efficiently desc
 ribe transport processes andpressure diffusion through fractures with real
 istic geometries\, i.e.\, characterized by high aspect ratios\, a hybrid-d
 imensional approach is discussed and applied to harmonic pumping tests. Fu
 rther\, it will be shown that this modeling approach could be also applied
  to derive effective hydro-mechanical properties of reservoir rocks on the
  REV scale in an\nefficient way. The consistent computational homogenizati
 on approach is therefore based on an extended Hill-Mandel macrohomogeneity
  condition. In the numerical studies\, synthetic fracture networks in a pe
 riodic unit cell are stochastically generated representing typical reservo
 ir scenarios. The resulting fluid-filled (fractured) poroelastic rock is n
 umerically investigated by coupled Finite Element Methods. From the numeri
 cal results in the time-domain\, we determine an effective pseudo-Skempton
  coefficient using computational homogenization approaches to replace the 
 heterogeneous medium by a macroscopic\, homogeneous viscoelastic substitut
 e medium. The effective pseudo-Skempton coefficient captures two viscous a
 ttenuation phenomena\, pressure diffusion\nparallel to the fractures and l
 eak-off perpendicular to the fractures. The two attenuation mechanisms are
  caused by viscous solid-fluid momentum interaction but are related to dif
 ferent inherent diffusion lengths and characteristic times (or frequencies
 ). We discuss how the analysis of the effective pseudo-Skempton coefficien
 t in frequency space provides a valuable tool for the analysis of intercon
 nectivity of fracture networks and for the determination of aspect ratios 
 of fractures in reservoirs.\n\nShort Bio : Prof. Dr.-Ing. Holger Steeb got
  his Civil Engineefing Degree from University of Stuttgart\, Germany in 19
 95. In 2002 he obtained his doctoral degree in Engineering from University
  of Stuttgart and in 2008\, his habilitation degree in Mechanics\, at Saar
 land University\, Saarbrücken\, Germany.\nIn 2004 he was a Post-Doc Fello
 w at Faculty of Applied Mathematics and Phisics\, NTUA Athens\, Greece and
  between 2002-2008 Academic Staff and Lecturer at Saarland\, University\, 
 Saarbrücken.\nFrom 2008-2009 he was an assistant Professore for Multi-Sca
 le Mechanics at University of Twente\, Enschede\, The Netherlands. From 20
 09-2015 he was Professor for Continuum Mechanics\, Ruhr-University Bochum\
 , Germany and since 2015 he is Professor for Computational Continuum Mecha
 nics\, Institute of Mechanics\, University of Stuttgart.\n 
LOCATION:GCB330 http://plan.epfl.ch/?lang=fr&room=GCB330
STATUS:CONFIRMED
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