Abstract

To investigate the natural fracture's effect on hydraulic fracturing crack propagation in the coal seam, the two-dimensional model of hydraulic fracturing crack intersecting natural fractures is built. Based on it, the laws of crack propagation and failure mechanism of natural fractures are studied by using the method of theoretical analysis and numerical simulation. The research suggests that angle of interaction between main crack and natural fracture, the horizontal differential principal stress and the development degree of natural fractures are the three main factors that affect direction of crack propagation. The direction of the propagation of crack tends along natural fracture due to shear failure in condition of low horizontal differential principal stress and low angle of interaction; Besides, with the increase of horizontal differential principal stress or angle of interaction, the propagating fracture tends to cross the natural fracture. The small size of natural fracture had little or no effect on the direction of the propagation of hydraulic fracture whereas the propagating fracture turns to natural fracture's direction when the size of natural fracture is large.

Keywords:
Upstream Oil & Gas, intersection angle, horizontal principal stress, asian rock mechanics symposium arms8, hydraulic crack, fracture, complex reservoir, propagate, hydraulic fracture, principal stress difference
Subjects:
Hydraulic Fracturing, Unconventional and Complex Reservoirs, Naturally-fractured reservoirs
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2014. Japanese Committee for Rock Mechanics. Permission to distribute - International Society for Rock Mechanics
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