HR: 0800h
AN: H11D-1284    [Abstracts]
TI: A Stochastic Analysis of Transient Two-Phase Flow in Heterogeneous Porous Media
AU: * Chen, M
EM: cmj1014@yahoo.com
AF: Los Alamos National Lab, Bikini Atoll Rd., SM 30, Los Alamos, NM 87545
AU: Keller, A
EM: keller@bren.ucsb.edu
AF: University of California,Santa Barbara, UC Santa Barbara, Santa Barbara, CA 93106
AU: Zhang, D
EM: don@ou.edu
AF: University of Oklahoma, 660 Parrington Oval, Norman, OK 73019
AU: Lu, Z
EM: zhiming@lanl.gov
AF: Los Alamos National Lab, Bikini Atoll Rd., SM 30, Los Alamos, NM 87545
AU: Zyvoloski, G
EM: gaz@lanl.gov
AF: Los Alamos National Lab, Bikini Atoll Rd., SM 30, Los Alamos, NM 87545
AB: The Karhunen-Loeve Moment Equation (KLME) approach is implemented to model stochastic transient water-NAPL two-phase flow in heterogeneous subsurface media with random soil properties. To describe the constitutive relationships between water saturation, capillary pressure and phase relative permeability, the widely used van Genuchten model, and Parker and Lenhard models are adopted. The log-transformed intrinsic permeability, soil pore size distribution, and van Genuchten fitting parameter are treated as stochastic variables that are normally distributed with a separable exponential covariance model. The perturbation part of these three log-transformed variables is decomposed via the Karhunen-Loeve expansion. The dependent variables (phase pressure, phase mobility, and capillary pressure) are expanded by polynomial chaos expansions and the perturbation method. Incorporating these expansions of random soil properties and of dependent variables into the governing equations for transient water-oil flow yields a series of differential equations in different orders. We construct the moments of the dependent variables from the solutions of these differential equations. We demonstrate the stochastic model with two-dimensional examples of transient two-phase flow with NAPL leakage. We also conduct Monte-Carlo simulations using the Finite Element Heat and Mass (FEHM) transfer code, whose results are considered `true' solutions. The match between the results from FEHM and KLME indicates the validity of the proposed KLEM application in transient two-phase flow; additional accuracy for KLME can be achieved by including higher-order terms. The computational efficiency of the KLME approach over Monte-Carlo methods is at least an order of magnitude for transient two-phase flow problems.
DE: 1829 Groundwater hydrology
DE: 1832 Groundwater transport
DE: 1869 Stochastic hydrology
DE: 1875 Vadose zone
SC: Hydrology [H]
MN: Fall Meeting 2005