--> Using Reservoir Geology Characterization Techniques in Waste Management Modeling, by C. F. Knutson and E. Inel; #90986 (1994).

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Abstract: Using Reservoir Geology Characterization Techniques in Waste Management Modeling

Carroll F. Knutson, Egg Inel

Reservoir geology characterization techniques were used to develop a conceptual geologic 3-D model of the vadose and aquifer zones underlying the Radioactive Waste Management Complex (RWMC) at the Idaho National Engineering Laboratory, Idaho. This conceptual model was used as the basis for developing a main frame 3-D computer model (GSCM). This paper deals only with the conceptual geologic modeling.

Geostatistical data was developed about the interbedded basalt and sediment sequence 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 geostatistical data was used to develop a hybrid (a large-scale plus a small-scale) subsurface model. The geometry of the subsurface units (large scale) was developed with a backstripping technique using stochastic techniques to obtain basalt flow and internal element geometries, and kriging techniques for sediment geometries.

The distributions of (1) matrix porosity, permeability, density, and saturation values, and (2) basalt rubble zone, lava tube, and fracture frequency and permeability (small scale) were generated from the geostatistical data. The small-scale parameters were stochastically assigned to locations in the existing wells in 0.33-m steps, for locations where no measured data was available. Large-scale and small-scale parameters were also stochastically assigned to an array of virtual wells located on a 60-m x-y grid covering the RWMC area. Thus, a subsurface data matrix was developed at a 0.33 × 60 × 60 m level that conformed to the geostatistical information.

The data matrix can be used as the conceptual geologic framework for modeling fluid flow and possible contaminant transport paths.

AAPG Search and Discovery Article #90986©1994 AAPG Annual Convention, Denver, Colorado, June 12-15, 1994