METHODS AND EVALUATION OF EXPLOSIVE FRACTURING IN OIL SHALE.

The Bureau of Mines developed methods for fragmenting oil shale formations with chemical explosives to prepare oil shale for in situ retorting and to evaluate the extent of fragmentation by various methods. A combination of three methods of explosive fracturing was used: the displacement and detonation of a liquid chemical explosive in a natural fracture system; the use of 60-pct dynamite to relieve stress conditions of the rock around the wellbore; and the use of pelletized TNT in a series of wellbore shots to fragment the oil shale. Evaluation of the fragmented zone by seismic measurements indicated that it was approximately 95 ft in diameter and 70 ft thick.