MODELING PROPAGATION OF FRACTURES IN LAYERED ROCK MASS DURING BLASTING AND HYDRAULIC FRACTURING

The article presents the analytical model and calculation results on fracture growth in layered rock mass during blasting and hydraulic fracturing in oil reservoirs. The stress state of fractured elastic rock mass is found using 3D boundary element method. The influence of strength characteristics of layered rock mass on the shape, size and area of radial fractures is determined. The presence of a stronger layer in rock mass restrains cross sectional growth of induced fractures as compared with the existing fractures in surrounding rock mass, i.e. nonuniform fracture of rock mass along boreholes and probable oversizes are prevented in this case. It is possible to adjust the shape of fractures by changing distribution of an explosive along the borehole. During hydraulic fracturing, fractures propagate chiefly along a softer rock layer if present.