In situ recovery technologies for tar sand and heavy oil are simulated at the Western Research Institute to prepare for pilot tests and commercial operations. Wide ranges of process parameters are tested in one-dimensional reactor tubes in which the tar sand or heavy oil is uniformly reconstituted to nearly the same permeability and porosity as the field resource. Three-dimensional process performance is verified in a reactor system that demonstrates the most promising operating parameters in consolidated blocks of the field resource. Both of these reactors are capable of testing combustion or steamflood processes at pressures as high as 1000 psi. Initial laboratory simulations have tested steamflooding of Asphalt Ridge tar sand for comparison with previous results from a pilot test near Vernal, Utah. Oil production rates, properties and residual saturations have been measured for different operating conditions, reservoir properties and bitumen concentrations. Corresponding operating parameters and production performance are compared to evaluate the relationships between the laboratory simulations and the field test results. These comparisons show that the residual oil saturations and sweep efficiencies in the laboratory tests are similar to the results of the field tests. 9 refs., 3 figs., 4 tabs.