Investigation of critical parameters in modified in-situ retorting

Recent results from operation of a 6 metric ton simulated, modified in-situ retort show that high (up to 3 m/day) retorting rates can be achieved with high (85%) oil yield and acceptable (<1000/sup 0/C) maximum temperature. These results were obtained with a bed of Colorado shale of broad (-30, +0.001 cm) size range containing a stepped grade change from 75 to 150 l/metric ton. Process control by steam and air injection rates, as stipulated by prerun model calculations, was demonstrated as was continuous estimation of retorting rate and oil yield from off-gas composition.