A viscoplastic model of creep in shale
Name
haghighat_et_al_2020_a_viscoplastic_model_of_creep_in_shale.pdf
Description
Accepted version
Size
3.27 MB
Format
Adobe PDF
Checksum (MD5)
3a1ce87494127ed4af5cc30f15c2a641
Author(s)
Haghighat, Ehsan
Rassouli, Fatemeh S
Zoback, Mark D
Juanes, Ruben
Date Issued
April 2020
Journal
GEOPHYSICS
Publisher
Society of Exploration Geophysicists
Citation
Ehsan Haghighat, Fatemeh S. Rassouli, Mark D. Zoback, and Ruben Juanes, A viscoplastic model of creep in shale, GEOPHYSICS 2020 85:3
Version
Author's final manuscript
Abstract
© 2020 Society of Exploration Geophysicists. We have developed a viscoplastic model that reproduces creep behavior and inelastic deformation of rock during loading-unloading cycles. We use a Perzyna-type description of viscous deformation that derives from a maximization of dissipated energy during plastic flow, in combination with a modified Cam-clay model of plastic deformation. The plastic flow model is of the associative type, and the viscous deformation is proportional to the ratio of driving stress and a material viscosity. Our model does not rely on any explicit time parameters; therefore, it is well-suited for standard and cyclic loading of materials. We validate the model with recent triaxial experiments of time-dependent deformation in clay-rich (Haynesville Formation) and carbonate-rich (Eagle Ford Formation) shale samples, and we find that the deformation during complex, multiscale loading-unloading paths can be reproduced accurately. We elucidate the role and physical meaning of each model parameter, and we infer their value from a gradient-descent minimization of the error between simulation and experimental data. This inference points to the large, and often unrecognized, uncertainty in the preconsolidation stress, which is key to reproducing the observed hysteresis in material deformation.
MIT Department
Massachusetts Institute of Technology. Department of Civil and Environmental Engineering
Massachusetts Institute of Technology. Department of Earth, Atmospheric, and Planetary Sciences
Terms of Use
Creative Commons Attribution-Noncommercial-Share Alike
Persistent DSpace Link
DOI of Published Version
https://doi.org/10.1190/GEO2018-0700.1
