Inverse problem in anisotropic poroelasticity: Drained constants from undrained ultrasound measurements

Journal Article · Fri Nov 20 04:00:00 EST 2009 · Journal of the Acoustical Society of America

OSTI ID:982045

Berryman, J G; Nakagawa, S

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.

• Research Organization: Ernest Orlando Lawrence Berkeley National Laboratory, Berkeley, CA (US)
• Sponsoring Organization: Earth Sciences Division
• DOE Contract Number: AC02-05CH11231
• OSTI ID: 982045
• Report Number(s): LBNL-3013E
• Journal Information: Journal of the Acoustical Society of America, Journal Name: Journal of the Acoustical Society of America; ISSN 0001-4966; ISSN JASMAN
• Country of Publication: United States
• Language: English

Related Subjects

54 ENVIRONMENTAL SCIENCES
58 GEOSCIENCES
DATA
EQUATIONS
ERRORS
GLASS
PACKINGS
POROSITY
SAND
SYMMETRY
USES
WORK