Fifth Annual International High Level Radioactive Waste Management Conference
Las Vegas, Nevada, April 1994, pp. 2160-2167
American Nuclear Society, La Grange Park, Ill., 1994
Estimating two-phase hydraulic properties by inverse modeling
Stefan Finsterle and Karsten Pruess
Lawrence Berkeley National Laboratory, Earth Sciences Division
University of California, Berkeley, CA 94720
Abstract.
Disposal of high-level nuclear waste in geologic formations requires characterizing the
hydrogeologic conditions at the potential site. This involves extensive data inter-pretation from
laboratory and field experi-ments which are being performed on different scales. Two-phase
flow processes are relevant if the potential site is located in the unsaturated zone, but they are
also studied for repositories beneath the water table if the waste packages generate significant
amounts of free gas. Numerical models are used for predicting the system behavior under
different hydrologic and thermal loads. Parameters appearing in the governing equations are
usually difficult to measure and subject to systematic errors. The strategy chosen to obtain
model-related formation parameters is to calibrate the numerical model using observations of
the system response. The practical relevance of parameter estimation for site characterization
and design of field and labo-ratory experiments motivated the development. The purpose of
this paper is to present the concept of parameter estimation, and to demonstrate the use of the
proposed method for the interpretation of hydraulic tests conducted under two-phase flow
conditions.
