Simulated in Situ Retorting of Oil Shale in a Controlled-State Retort. II. Heat Soaking Experiments

摘要

Oil shale from the Green River formation has been retorted in three experiments under closely controlled conditions in the controlled-state retort using a very slow heating rate (2.4 exp 0 F/h). In two of the experiments, all of the shale was retorted and in the third, the bottom 40% of the shale was left unretorted. The oil yield was less than 70% of Fischer Assay for the completed experiments and residual carbon content was higher because of the slow heating rate. Nitrogen and sulfur content of the oils washed from the shale of the interrupted experiment and of the periodic oil samples taken at the retort outlet during the experiment indicate either that nitrogen is more prevalent in the last oils released from the shale and sulfur is prevalent in the first oil released or that there is a chromatographic effect on the oil as it passes over the unretorted shale. Also the amount of bitumen extractable from the partially retorted shale of the interrupted experiment peaks at a lower temperature than for shales retorted at faster heating rates. These data imply that operators of vertical modified in situ retorts can expect higher concentrations of nitrogen in the oil product at the end of their retort burns and that shale retorted at the fringes of retorts will give lower than ideal yields. (ERA citation 05:013104)