Features of stress state and jointing as well as their effect on hydraulic fracture propagation direction in coal seams are considered. The flow resistance in drainage areas is analyzed depending on hydrofracture orientation, thickness of seams and spacing of holes. The comparison of one-stage and multi-stage hydrofractures created in-plane and orthogonally to hole axes is given. In simulated reservoir conditions, permeability of dense coal is studied without a fracture and with a through propped fracture subjected to confining pressure. The recommendations are developed for improving efficiency of gas drainage in coal seams based on in-mine hydraulic fracturing.
