Method for extracting gas by fracturing coal seam through combination of hydraulic slotting and multi-stage combustion impact wave
US11131172B2 · kind B2 · utility
Assignees
Inventors
Key dates
| Filing date | Oct 29, 2018 |
| Grant date | Sep 28, 2021 |
| Priority date | — |
| Expiry date | Oct 29, 2038 |
Classification
- Technology area (CPC E)Fixed Constructions
- CPC primaryE21B43/2605
- WIPO fieldCivil engineering
- WIPO sectorOther fields
Abstract
A method for extracting gas by fracturing a coal seam through a combination of hydraulic slotting and multi-stage combustion impact wave comprises cutting slots in an impact borehole using a hydraulic slotting equipment to perform pressure relief and permeability enhancement on a coal seam and enlarge a N2 (nitrogen gas) or CO2 (carbon dioxide gas) storage space, injecting a large amount of N2 or CO2 into the borehole by means of a high pressure gas cylinder and a pressure reducing valve through a gas injection and extraction pipe, then injecting a certain amount of methane and dry air into a high-temperature and high-pressure combustion chamber by means of the high pressure gas cylinder and the pressure reducing valve, so that the gases are mixed and combusted to form high-temperature and high-pressure impact wave to push a piston to compress the N2 or CO2, thereby generating a large number of factures on the coal seam around the impact borehole under guiding action of the slots. The impact wave is repeatedly generated to form a multi-stage impact, and the impact of the next stage is based on the impact of the previous stage, so that the fractures on the coal seam around the boreh…
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.