Explosive placement for explosive expansion toward spaced apart voids

摘要: A subterranean formation containing oil shale is prepared for in situ retorting by initially excavating a pair of spaced apart voids, leaving an intervening zone unfragmented between the voids. The has substantially parallel free faces adjoining void. plurality elongated blasting holes are formed formation, longitudinal axis each hole being perpendicular to zone. At least two deck loads explosives placed hole, with load longitudinally from adjacent stemming. explosive then detonated single round explosions time delay expanding zones toward both fragmented mass particles retorted recover shale.