Coal seam gas extraction method synergistically reinforced by hydraulic punching cave making and CO2 blasting cracking displacement

Abstract

The invention discloses a coal seam gas extraction method synergistically reinforced through hydraulic punching cave making and CO2 blasting fracturing displacement. The coal seam gas extraction method comprises the following steps that 1) performing hydraulic punching cave making construction; 2) performing CO2 blasting drilling construction; 3) CO2 blasting; and 4) gas extraction, monitoring and displacement. The coal body around the hole is unstable and damaged through hydraulic punching and cave making, a crack expansion network in a certain range is formed, and the permeability of the coal seam is remarkably improved; and meanwhile, the coal body around the cave-making chamber is fractured through a CO2 fracturer to expand a fracture grid, is desorbed by combining with gas displacement, is transported into the cave-making chamber, and is transported to an extraction pipeline through a layer penetrating drill hole. The invention provides a novel synergistically reinforced gas extraction treatment method for soft, low-permeability, high-gas-content and difficult-to-extract coal seam areas, so that the gas in the coal seam can meet the extraction requirement in a short time, the coal seam extraction progress is accelerated, and meanwhile, the safety of coal extraction is improved.

Description

technical field [0001] The invention belongs to the technical field of coal seam gas drainage, and in particular relates to a hydraulic punching and CO 2 Blasting fracturing displacement synergistically enhanced coal seam gas drainage method. Background technique [0002] During the formation process, coal first experienced long-term complex physical, chemical and geochemical changes, and then experienced a series of plasticity, toughness, and flow deformation processes through long-term geological tectonic movements, resulting in soft and broken coal bodies. Due to continuous tectonic movements in the Indosinian, Yanshanian and Himalayan periods, soft and low-permeability coal seams exist in most coal fields in my country. At the same time, my country's coal-bearing strata are mostly Jurassic and Carboniferous Permian, and most coal seams are low-permeability soft coal seams with complex geological conditions. Moreover, with the increase of mining intensity, it extends to...

AI Technical Summary

Problems solved by technology

However, due to the particularity of the complex geological conditions of my country's coal seams, the permeability of coal seams is 1-2 orders of magnitude lower than that of the United States, Australia and other countries. Rising demand for coal mining

[0004] In addition, according to relevant research by some scholars, the pore structure of coal in my country is complex, and the proportion of micropores is relatively high, so that a large amount of gas is adsorbed on the inner surface of micropores, resulting in high gas content in coal seams, which is not easy to desorb, and gas drainage is difficult

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