Compaction localization and constitutive behavior of weak porous sandstone.
Conference
·
OSTI ID:966621
- Clarkson University, Potsdam, NY
A combined experimental and constitutive modeling program for weak porous sandstone deformation is described. A series of axisymmetric compression tests were performed over a range of mean stresses to study dilatational, compactional and transitional regimes. Experimental results were used both to derive constitutive parameters for testing localization theory and to parameterize a poroelastic-plastic model. Observed strain localization, imaged syn-deformationally using acoustic emissions, includes high- and low-angle shear and low angle compactional features or 'bands'. Isotropic elastic moduli measured via unloading loops show a progressive degradation pre-failure as decreasing functions of work-conjugate plastic strains and increasing functions of stress magnitude. The degradation pathway is unique for samples which underwent localization versus those that underwent spatially pervasive pore collapse. Total shear and volume strains are partitioned into elastic and plastic portions including the ''coupling'' strain associated with modulus degradation. Plastic strain calculated with and without the coupling term is compared with regard to localization predictions. Both coupled and uncoupled cases predict high angle shear bands for uniaxial and low mean stress conditions on the dilatational side of the yield surface. Uncoupled predictions show progressively lower angle shear bands approaching the transitional regime (stress conditions approaching the 'cap' surface). When elastic-plastic coupling is accounted for, compaction bands are predicted for the transitional regime, as are observed in the experiments. Finite element modeling efforts are described using a 3-invariant, mixed-hardening, continuous yield surface, elasto-plasticity model that includes several features important for porous sandstone constitutive behavior and observed experimentally, including non-associativity, nonlinear elasticity, elastic-plastic coupling, and kinematic hardening. Modeled deformational behavior attending stress paths relevant for several reservoir production scenarios are described.
- Research Organization:
- Sandia National Laboratories
- Sponsoring Organization:
- USDOE
- DOE Contract Number:
- AC04-94AL85000
- OSTI ID:
- 966621
- Report Number(s):
- SAND2009-3493C
- Country of Publication:
- United States
- Language:
- English
Similar Records
Strain localization and elastic-plastic coupling during deformation of porous sandstone
Cap plasticity models and compactive and dilatant pre-failure deformation
Dilatant hardening of fluid‐saturated sandstone
Journal Article
·
Mon Sep 11 20:00:00 EDT 2017
· International Journal of Rock Mechanics and Mining Sciences
·
OSTI ID:1464178
Cap plasticity models and compactive and dilatant pre-failure deformation
Conference
·
Wed Feb 16 23:00:00 EST 2000
·
OSTI ID:751348
Dilatant hardening of fluid‐saturated sandstone
Journal Article
·
Wed Feb 25 19:00:00 EST 2015
· Journal of Geophysical Research. Solid Earth
·
OSTI ID:1402290