HR: 1330h
AN: H22A-0909    [PDF]
TI: Phase Structure in a Centrifugal Field: Impact of Capillary Heterogeneity and Angular Velocity
AU: * Holt, R M
EM: rmholt@olemiss.edu
AF: The University of Mississippi, Dept. of Geology and Geological Engineering 118 Carrier Hall, University, MS 38677 United States
AU: Glass, R J
EM: rjglass@sandia.gov
AF: Sandia National Laboratories, Flow Visualization and Processes Laboratory, Albuquerque, NM 87185-0735 United States
AU: Sigda, J M
EM: sigda@nmt.edu
AF: New Mexico Bureau of Geology and Mineral Resources, New Mexico Tech, Albuquerque, NM 87106 United States
AU: Mattson, E D
EM: matted@inel.gov
AF: Idaho National Engineering and Environmental Laboratory, Geosciences Research Department, Idaho Falls, ID 83415-2107 United States
AB: We investigate the evolution of phase structure in a centrifugal field by simulating the simplest of two-phase experiments, the stabilized displacement of a denser wetting phase (e.g., water) by a lighter non-wetting phase (e.g., air) within a heterogeneous porous medium. We model this displacement (drainage) using a Modified Invasion Percolation (MIP) approach that includes both capillary forces and a stabilizing centrifugal force. We generate random fields of spanning pressures to represent capillary heterogeneity. The style of heterogeneity varies from unstructured (uncorrelated) to partially structured (layered system with a random overprint) to fully structured (layered with no random overprint). Drainage is simulated for each layered system twice: once for drainage perpendicular to layers and once for drainage parallel to layers. Our results show that the influence of capillary heterogeneity varies with angular velocity in a centrifugal field. As the angular velocity is increased, non-wetting phase invasion and phase structure become increasingly insensitive to capillary heterogeneity, regardless of its style or orientation. Higher spanning pressure variance, however, increases the sensitivity to capillary heterogeneity and leads to less drainage at a given angular velocity. In general, contact area between the wetting and non-wetting phase increases as the heterogeneity becomes less structured and decreases with increasing angular velocity. Because phase structure critically influences flow processes and petrophysical properties (pressure-saturation, relative permeability, electrical resistivity, etc.), the design of centrifugal experiments must carefully consider this interplay between capillary heterogeneity and centrifugal force.
DE: 1866 Soil moisture
DE: 1875 Unsaturated zone
DE: 1894 Instruments and techniques
SC: Hydrology [H]
MN: 2003 Fall Meeting