Method of detonating explosives for fragmenting oil shale formation toward a vertical free face

摘要: Oil shale formation is explosively expanded toward a limited void volume for forming an in situ oil retort subterranean containing shale. In one embodiment, the form narrow vertical slot excavated within site, leaving at least portion of unfragmented site adjacent free face slot. Explosive placed row blasting holes remaining face. The are mutually spaced apart along length slot, and extends generally parallel to detonated time delay sequence starting near end progressing expanding fragmented permeable mass particles retort.