Abstract: A method of opening productive formations by slot-perforating, includes providing a working fluid which contains water, and abrasive component, and an additive; supplying the working fluid at a high pressure towards a formation so as to cut slots and to provide an inflow of oil, gas or hydro-geological liquid from the formation into a borehole; and using as the additive-ethylene glycol so as to reduce density of the working fluid and therefore to increase a speed of jet of the working fluid due to increase of kinetic energy of particles of the abrasive component.