A Design for Project Bronco, an Experiment for Nuclear Fracturing and in Situ Retorting of Oil Shale

Résumé du livre

This report describes Project Bronco, a proposed 50-kiloton nuclear explosion experiment. The detonation will fragment and fracture a deep, thick oil shale deposit which will subsequently be retorted in place. Bronco will provide information related to: the technical and economic feasibility of the basic concept, a predictive capability for the physical effects of nuclear explosions, and the distribution of radioactivity and its behavior during retorting. Although the Bronco experimental design is based on a particular site in the Piceance Creek Basin, a preshot investigation will determine whether the nominated site will meet the technical and safety criteria for a first nuclear explosion in oil shale. Following site confirmation, holes will be drilled for fracture studies, for emplacing the explosive, and for shock wave measurements. The explosion is expected to produce a chimney 230 ft across and 520 ft high (measured up from the shot point), containing over one million tons of fragmented oil shale. Fractures may extend as far as 460 ft. laterally beyond the chimney edge. Postshot drilling will reveal the size and shape of the chimney, the extent of fracturing, and the distribution of heat and radioactivity. The final design of the in situ retorting experiment will depend on results of the postshot exploration and on laboratory research currently underway. Tentatively, mixtures of air and recycle gas will be injected via drill holes to the chimney top. Drill holes to the chimney bottom will remove off-gas, oil mist, and liquid oil. During retorting, measurements will be made of temperatures in the chimney. Samples of gas and oil will be analyzed for physical characteristics, chemical composition, and radioactive content, if any. Additional data on retorting efficiency will be obtained in post-retorting drill holes.