DOE is conducting field research on true in situ fracturing and retorting of oil shale.The oil shale seam is about 40 ft. thick and has 50 to 200 ft. of overburden. This formation is located just west of Rock Springs, Wyoming. Several different sites have been tested in this research effort. Methods for fracturing oil shale under true in situ conditions at the field laboratory include electro-linking, hydraulic fracturing, well-bore explosives, slurried explosives and combinations of the above. One method that showed initial promise was hydraulic fracturing followed by injection and detonation of a slurried explosive in the fracture created. The objective of the fracturing experiment was to produce a distributed fracture network with sufficient porosity, permeability and uniformity for retorting. Three horizontal hydraulic fractures were formed in the shale bed. A slurry explosive was inserted and detonated in two of the three fractures. Post-detonation fracture assessment involved direct coring, well bore logging (including TV and caliper), air acceptance, and tracer flow tests. The results indicate that the stresses were sufficient to cause fracturing but that there was no significant tumbling. The major fractures apparent after detonation of the slurry were in the same positions as the hydraulic fractures. Flow logging showed that most of the air passage through the system was through these fractures. Preliminary modeling of the system shows that the existing fractures should support combustion and that shale will be retorted as much as one meter away from the fractures. Since the fractures are less than two meters apart, retorting should be possible. To test this idea, bench scale tests on blocks of oil shale with small fractures are being performed. A small scale two-hole ''burn''will be attempted in late September, followed by a full scale burn of the five spot pattern.