METHOD OF EXTRACTING GAS BY LOOSENING A COAL BED BY COMBINING HYDRAULIC CUTTING OF GROOVES AND COMBUSTION SHOCK WAVE ACTING IN SEVERAL STEPS

摘要

FIELD: oil and gas industry.;SUBSTANCE: invention relates to a method of extracting gas by loosening of a coal bed by combining hydraulic cutting of grooves and a combustion wave acting in several steps. Proposed method comprises the following stages. First, an impact well is formed in a coal bed and a large number of grooves is cut around the impact well by means of equipment for cutting the grooves with a high-pressure water jet. Then, porous cylinder with piston is arranged in impact well. One end of the pipeline for gas injection and extraction is inserted through the piston into the porous cylinder, and the other end of the pipeline for injection and extraction of gas comes out of the impact well. Then one end of the pipeline for supplying the shock wave to the porous cylinder is placed and another end of the pipeline for supplying the shock wave to the combustion chamber outside the impact well is connected. Pipeline for supplying the shock wave does not pass through the piston. Then impact well is injected with injection of N₂ or CO₂ into impact well by means of pipeline for gas injection and extraction with subsequent closing of pipeline for gas injection and extraction. After that, combustible gas and auxiliary gas are injected into combustion chamber. Combustible gas is ignited in combustion chamber by means of control system, wherein the shock wave generated by combustible gas combustion is supplied to the porous cylinder by means of the shock wave supply pipeline for action on the piston and piston slides along pipeline for injection and production of gas for compression of N₂ or CO₂ in impact well, thus forming a large number of cracks around the impact well under the guide action of the grooves. Pipeline is opened for injection and production of gas for continuous delivery of N₂ or CO₂ into impact well for compression of piston in order to return piston to initial position and then to close pipeline for injection and extraction of gas. Then, the above stages of ignition of combustible gas and opening and closing of the pipeline for injection and production of gas for compaction and compression of N₂ or CO₂ are repeated several times for formation of cracks in the coal seam, so in the coal seam around the impact well there formed are networks of cracks.;EFFECT: technical result consists in improvement of gas production efficiency.;6 cl, 1 dwg