METHOD OF HYDRAULIC FRACTURING OF COAL BED AND DOWNHOLE DEVICE FOR ITS IMPLEMENTATION Russian patent published in 2024 - IPC E21B43/26 E21C37/06 E21C45/04 

FIELD: mining.

SUBSTANCE: group of inventions relates to mining, in particular to extraction of methane from coal beds. Method of hydraulic fracturing of a coal bed includes drilling a bed well, placing a device in the well for hydraulic fracturing, filling the sealers of the device with a working fluid until fixation in the well, performing interval hydraulic fracturing in the space between sealers with formation of artificial cavities and expansion of natural fractures, introduction of propping agent – proppant into newly formed artificial cavities and expanded natural cracks. When filling the device with working fluid, each sealer is first compressed in the axial direction by supplying the working fluid to the rod end of the cylinder with a rod and a piston installed in each sealer, then fixed in the well. Hydraulic fracturing is performed by working fluid with propping agent. After hydraulic fracturing, pressure is equalized in expanded cracks and formed artificial cavities and in the well by switching off the working fluid pressure first in the sealer on the side of the wellhead, and after removal of the spacer force in it – in the sealer on the side of the well bottom. Downhole device for hydraulic fracturing of a coal bed comprises a housing made in the form of a cylinder with radial holes in the wall for the working fluid passage, a rod with an axial through hole installed in the cylinder and equipped with a piston, and two sealers with tips, installed coaxially with the housing, one is dead-end sealer, the other is through. In the housing there are axial channels connected to the corresponding radial channels. Cylinder with rod and piston is installed inside each sealer. At that, the cylinder base forming the piston cavity is rigidly connected to the housing, and the rod end opposite to the piston is connected to the tip. In each piston parallel to its axis there are three through holes, in two of them oppositely oriented check valves are installed, and the third one is connected to the housing by means of a flexible hose.

EFFECT: higher efficiency and reliability of hydraulic fracturing of coal bed.

2 cl, 7 dwg