The occurrence in this deposit has a dome-shaped configuration and is represented by carbonaceous blankets. The maximum deposit layer in the dome section is about 100 m; the stratification depth is 1400 to 1520 m; the mantle is composed of clay-filled, practically impervious carbonaceous rock 90 to 150 m thick.

On the underside, the deposit is connected with water under pressure, with an open surface contact. The connection between the water-bearing and oilbearing zones is partly screened off by dense interlayers. The layer of the underlying water-bearing limestone is 70 to 200 m thick.

The optimal design of mining the deposit calls for the explosion of three charges, of 20 to 30 kilotons each, and their placement in the center of the deposit under the water-oil interface. Both the water-bearing and the oilsaturated sections of the deposit will be affected by the mechanical effect.

The result anticipated from the application of explosions with a subsequent use of the head of the underlying water during the mining of the deposit is represented by a considerable increase in the current yield of oil and its stabilization at a high level for a long period (Fig. 8) of time.

In addition, nuclear explosions may be used in schemes with frontal, contour or internal-contour flooding.

Chapter V EXPERIMENTAL UNDERGROUND EXPLOSION IN SALT

A 1.1 kiloton underground explosion in salt has been undertaken in the USSR. The depth of the charge placement was 160 m/kt1/3.4.

The section where the experimental explosion took place represents a large dome-shaped elevation of a salt massif. The thickness of the layer above the salt along the line of the well is rather thin and reaches only 7-8 m. The salt is composed of medium and large crystals, with individual crystal dimensions of 2-3 cm and a clearly expressed lamination. Salt lamina have a 70° angle in the northwest direction (280°). The salt layers are 2-15 cm thick and alternate with interlayers 0.1-0.3 cm thick composed of carbonates and sulfates.

The experimental explosion was to solve the following problems: Investigate the possibilities of creating, by means of a nuclear explosion, an underground cavity of a large volume in the salt mass, and its later use as an underground facility; determine the configuration and dimensions of the explosion cavity as well as of the deformation zones; investigate the seismic effect of the explosion upon surface structures, buildings and wells; and investigate the distribution of radioactive products in the salt mass and on the surface. These problems were solved. The explosion was totally underground. The eaving of the rock in the epicenter of the explosion was 2 m.

The general heaving of the soil was observed in a 60 m area around the picenter (Fig. 10).

Six holes were drilled into the central explosion zone. This was done to deermine the configuration of the cavity, its dimensions and volume.

The cavity has a shape close to an ellipsoid of rotation with a large vertical emiaxis (Fig. 9).

The maximum span of the cavity is 37 m in height, the horizontal radius of he cavity on the charge placement level is 12-14 m, the volume of the cavity is 4,200 m3, one-third of the cavity volume in the lower part is filled with fused salt and crumbled pieces of halite and rock. The volume of the pile is 4000 m3. The volume of the empty space filled with water is 10,000 m3.

The explosion cavity is bordered by a zone of crushed halite, 1.5 to 6.5 m hick. Fissures of the rupture can be traced 83 m up, 29 m down and 35 m aterally from explosion center. Individual fissures extended for 150-200 m.