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Inverse problem in anisotropic poroelasticity [electronic resource] : Drained constants from undrained ultrasound measurements

Published
Berkeley, Calif. : Lawrence Berkeley National Laboratory, 2009.
Oak Ridge, Tenn. : Distributed by the Office of Scientific and Technical Information, U.S. Dept. of Energy.
Additional Creators
Lawrence Berkeley National Laboratory and United States. Department of Energy. Office of Scientific and Technical Information
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Summary
Poroelastic analysis has traditionally focused on the relationship between dry or drained constants which are assumed known and the saturated or undrained constants which are assumed unknown. However, there are many applications in this field of study for which the main measurements can only be made on the saturated/undrained system, and then it is uncertain what the eects of the uids were on the system, since the drained constants remain a mystery. The work presented here shows how to deduce drained constants from undrained constants for anisotropic systems having symmetries ranging from isotropic to orthotropic. Laboratory ultrasound data are then inverted for the drained constants in three granular packings: one of glass beads, and two others for distinct types of more or less angular sand grain packings. Experiments were performed under uniaxial stress, which resulted in hexagonal (transversely isotropic) symmetry of the poroelastic response. One important conclusion from the general analysis is that the drained constants are uniquely related to the undrained constants, assuming that porosity, grain bulk modulus, and pore uid bulk modulus are already known. Since the resulting system of equations for all the drained constants is linear, measurement error in undrained constants also propagates linearly into the computed drained constants.
Report Numbers
E 1.99:lbnl-3013e
lbnl-3013e
Other Subject(s)
Note
Published through SciTech Connect.
11/20/2009.
"lbnl-3013e"
Journal of the Acoustical Society of America ISSN 0001-4966; JASMAN FT
Berryman, J.G.; Nakagawa, S.
Earth Sciences Division
Funding Information
DE-AC02-05CH11231
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