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• production during drilling of core hole 26-88-1. Notice that after placement of the packer in the upper portion of the R6, essentially no waterwas produced until midway through the RS zone. A[ the site of the proposed solution cavity tests, the groundwater level is approxima[ely 400 ft below the surface, with the dissolution surface some 32.8 ft above the top of the Boles Bed. The condition of the fluid during dissolution, the degree of saturation of the host medium, and the fluid/rock conditions after abandonment are critical to operations and long-term stability. The solution cavity will be developed using elevated temperature, partially saturated to saturated, fluid circulated within the cavity. The fluid pressure during dissolution exceeds the in situ initial fluid pressure and could tend to leak off. This leak-off is prevented by precipitation of sodium bicarbonate in the flow paths as the pregnant fluid flows away from the solution cavity and cools down. Following completion of production, the production holes will be sealed. The fluid in the solution ca~riry will cool down, precipitate out some bicarbonate, and the remaining fluid pressure could either remain equal to the shut-in pressure or subside to the pressure of the overlying strata (approximately equal to the existing water table some 400 ft from the surface). • During production by solution mining, the most probable scenario is that of saturated 1 undisturbed material below the dissolution surface and fluid pressure in a sealed cavity. The ~• least stable configuration is when the fluid pressure in the cavern is in equilibrium with the overlying groundwater. This is possible after the cavity has been sealed. Thermal Environment-The fluid introduced to develop the solution cavity will have a temperature of approximately 200 degrees, thereby causing temperature changes and thermally induced stresses in the host rock. In addition, elevated temperatures in the host rock could cause some reduction in rock strength. Tesu by Dowell Schlumberger show a slight increase in strength forcrystalline nahcolite at temperatures of 200'F. Oil shale strength generally decreases with temperature. 3.2 MATERIAL PROPERTIES Laboratory data is available from many sources foroil shales and nahcolite rock oil shales. The previous analysis (JFTA, August, 1988) used properties available primarily from Multi Minerals/IRI core holes, the USBM test mine at Horse Draw, and data from the Dowell • Schlumberger repon. Since that time, core hole NaTec 26-88-1 was completed (JFTA, December, 1988) and other site-specific data became available. J. F. T. Agapito & Associates, Inc. 10 r