HR: 1340h
AN: H23G-1730    [Abstracts]
TI: A Multi-Point Geostatistical Inverse Model for the Identification of Connected Permeable Subsurface Structures
AU: * Ronayne, M J
EM: mronayne@stanford.edu
AF: Department of Geological and Environmental Sciences, Stanford University, Stanford, CA 94305-2115, United States
AU: Gorelick, S M
EM: gorelick@pangea.stanford.edu
AF: Department of Geological and Environmental Sciences, Stanford University, Stanford, CA 94305-2115, United States
AU: Caers, J
EM: jef@pangea.stanford.edu
AF: Department of Energy Resources Engineering, Stanford University, Stanford, CA 94305- 2220, United States
AB: Depositional features such as fluvial channel bodies often provide structural pathways for fluid and solute transport in the subsurface. In this work, we analyze complex aquifer test response data from an alluvial fan deposit in northern California. The subsurface architecture is characterized by discrete channel deposits embedded within finer-grained and less permeable floodplain deposits. We adopt a discontinuous facies framework to represent the aquifer structure. The distribution of channels is modeled using a sequential stochastic simulation technique based on multiple-point geostatistics. We couple the geostatistical simulation model with a groundwater model and apply an inverse method to find channel locations that are consistent with the hydrologic observations. The inversion routine, which informs simulations of the aquifer structure, relies on direct perturbation of nodal conditional pdfs that describe the probability of each facies. Results indicate that in response to pumping, rapid hydraulic head declines in a distant area of the aquifer system are facilitated by the presence of vertically interconnected channel deposits. The inverse model, guided by the dynamic head- response data, produces a similar channel structure at each successful realization.
DE: 1829 Groundwater hydrology
DE: 1846 Model calibration (3333)
DE: 1847 Modeling
DE: 1869 Stochastic hydrology
SC: Hydrology [H]
MN: 2007 Fall Meeting