51st U.S. Rock Mechanics/Geomechanics Symposium,
San Francisco, California, USA
2017. American Rock Mechanics Association
0 in the last 30 days
29 since 2007
Show more detail
ARMA Member Price:
ARMA Non-Member Price:
ABSTRACT: The laboratory experiments typically performed to measure poroelastic properties evaluate the macroscopic deformation of samples. While these techniques are adequate for capturing bulk effects, they fail to capture fine detail related to the actual deformation of constituent mineral phases because the measurement captures the combined effect of pore network geometry change and polymineralic deformation. A more precise measurement of mineral deformation in fluid saturated porous media has the potential to improve understanding of poroelastic behavior and material failure where pore pressure is present.
Neutron diffraction has emerged as a unique and powerful technique for measuring the localized lattice strains of mineral phases inside of geological materials. The highly penetrating nature of neutrons also permits interrogation of the interior regions of geological samples even when they are contained in otherwise difficult to access or opaque structures such as pressure vessels. This paper summarizes a set of neutron diffraction experiments that were performed with geological materials of varying porosity and permeability using a custom-designed triaxial pressure cell. The results confirm that neutron diffraction has the potential to become a useful tool for quantifying the behavior of distinct crystalline phases within porous media.
Poroelastic behavior in rock mechanics has been studied in great detail since the foundational works of Terzaghi and Biot (Biot, 1941). There have been a number of prior efforts focused on experimental measurement of poroelastic parameters, including comparative approaches (Lion et al, 2004). The classical Biot formulation of poroelastic constants used to represent bulk material response may also be represented as combinations of distinct elastic moduli related to material porosity, grain compressibility, and pore fluid compressibility (Gassman, 1951). This formulation is useful for calculating expected property variation for changes in pore, matrix or fluid composition. These component moduli can be individually measured in a straight-forward manner via traditional drained, undrained and unjacketed tests when isotropic assumptions are made. The measurements result in an overdetermined number of poroelastic parameters and so some work has attempted to develop procedures for fitting moduli to the obtain the traditional four poroelastic parameters for the isotropic material system (Hart and Wang 1995; Hart and Wang, 2001).
Number of Pages
Looking for more?
Some of the OnePetro partner societies have developed subject- specific wikis that may help.