Reservoir characterization techniques were used to develop a hybrid (two scale) 3D model of the 180 m thick interbedded basalt flow and sediment system that constitutes the vadose zone underlying the Radioactive Waste Management Complex (RWMC) at the Idaho National Engineering Laboratory, Idaho. Geostatistical data was captured from a study of well logs, cores, and cuttings from the subsurface at the RWMC and from nearby outcrops. In general the data was cast in the form of stochastic distribution equations, allowing easy assignment of parameter values.

The geometry of the units comprising the vadose zone was developed with a backstripping technique and stochastic interpolation between the wells using a geostatistical model for flow geometry and kriging for sediment geometry.

Porosity, permeability, and saturation values were stochastically assigned to locations in the existing wells in 0.33 m steps from the surface to the aquifer where no measured data was available and to an array of virtual wells on a 60 m x-y grid covering the RWMC area. Thus, a data matrix was developed utilizing the geometric model and stochastic distribution equations, that provided flow and storage capacity data in 0.33 m steps in the z axis with an x-y spacing of 60 m or less.

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