A method for hot steam flooding gas to improve gas drainage efficiency

Abstract

Disclosed is a hot steam displacement gas method for improving gas extraction efficiency. The hot steam displacement gas method for improving the gas extraction efficiency is suitable for improving the extraction efficiency of coal bed gas, and particularly suitable for extracting underground low air permeability coal bed gas from a coal mine. The hot steam displacement gas method for improving the gas extraction efficiency includes: firstly, constructing a gas extraction drill hole in a coal bed, feeding a hot steam conveying pipeline into the gas extraction drill hole, guiding the hot steam conveying pipeline to the exterior of the gas extraction drill hole, and connecting a stop valve; secondly, connecting the stop valve with an explosion prevention steam generator through the hot steam conveying pipeline, installing a steam pressure gauge and the other stop valve on an outlet of the steam generator, installing a steam-water separator at a corner of the hot steam conveying pipeline, where the height of the hot steam conveying pipeline is decreased, and connecting a water outlet of the steam-water separator with a drain valve group; installing a safety valve in the gas extraction drill hole through a steel pipe; leading an extraction branch pipe out of a gas extraction main pipe to the gas extraction drill hole, sealing the gas extraction drill hole, and closing a valve on the extraction branch pipe; opening a valve on the hot steam conveying pipeline, and injecting high temperature steam into the gas extraction drill hole; sequentially closing the steam generator and the valve on the hot steam conveying pipeline after one hour, opening the valve on the extraction branch pipe, and extracting the gas.

Description

technical field [0001] The invention relates to a method for displacing gas by hot steam to improve gas extraction efficiency, and is especially suitable for efficient gas extraction of coal seams with low air permeability and high adsorption in underground coal mines. Background technique [0002] The gas contained in high-rank coal and low-rank coal in China accounts for more than 2 / 3 of the total resources, and the occurrence of gas (coal bed methane) is special: it has the characteristics of microporosity, low permeability and high adsorption. The average permeability of coal seam is only 1.1974×10 -18 ~1.1596×10 -14 m 2 . Among them, the permeability is less than 0.1987×10 -16 m 2 accounted for 35%, 0.1987×10 -16 ~0.1987×10 -15 m 2 Accounted for 37%, greater than 0.1987×10 -15 m 2 only 28%. U.S. coalbed methane surface development selection areas usually require that the permeability of coal seams should not be lower than 0.1987×10 -15 m 2 , while the perme...

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Problems solved by technology

However, these methods can only improve the drainage efficiency from the perspective of improving the gas permeability of the coal seam, and the coal seam also has the characteristics of high adsorption. Even if cracks are formed, the gas in the micropores of the coal body is difficult to desorb and migrate, which leads to There is still a large amount of gas gushing out during coal seam excavation or mining

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