HR: 1340h
AN: H33A-1373    [Abstracts]
TI: Permeability prediction in compaction bands using pore-scale numerical flow simulations
AU: Keehm, Y
EM: keehm@kongju.ac.kr
AF: Kongju National University, Dept. of Geoenvironmental Sci 182 Shinkwan-Dong, Kongju, 314-701 Korea, Republic of
AU: Sternlof, K
EM: kurster@pangea.stanford.edu
AF: Stanford University, Dept. of Geological and Environmental Sci., Stanford, CA 94305 United States
AU: * Mukerji, T
EM: mukerji@pangea.stanford.edu
AF: Stanford University, Dept. of Geophysics, Stanford, CA 94305 United States
AB: Permeability measurements can be difficult to obtain when the target has limited dimensions, sample availability is restricted, or the material is unconsolidated. With subsurface cores of sandstone containing thin (~1cm), tabular compaction bands (CBs), all three challenges can arise. As an alternative, we uses a physics-based computational method for estimating permeability from thin section - Lattice-Boltzmann flow simulations conducted on stochastic realizations of 3D pore structure generated from digital thin-section images. We applied the technique for a set of thin-sections from the Aztec Sandstone of southeastern Nevada, an exhumed analog for CB-rich sandstone aquifers and reservoirs. The main idea is to apply the numerical technique to host rock and CB individually, and quantify the permeability contrast. The Aztec sandstone samples also have different fine-scale heterogeneities in addition to the existence of CBs - it has two distinct sizes of grains and different sorting in beds. Applying the numerical technique to individual regions, which includes all possible combination of different fine scale heterogeneities such as host rock or CB, different grain sizes, and different degrees of sorting, we can obtain predicted permeability and its variability in each region. By combining these predicted permeability values in effective medium theory context, permeability for the rock with all of these fine-scale features can be predicted. Our estimates agree well with available data - a few millidarcys (CB) to a few Darcys (host rock) - capturing nearly the full range of formation permeability from thin sections. Pervasive arrays of these low-permeability CBs have been shown capable of exerting substantial fluid-flow effects at scales relevant to reservoir and aquifer production and contaminant migration in sandstone.
DE: 5112 Microstructure
DE: 5114 Permeability and porosity
DE: 8012 High strain deformation zones
SC: Hydrology [H]
MN: Fall Meeting 2005