Method for extracting coal bed gas by negative pressure on ground through gas-coal simultaneous extraction

Abstract

The invention provides a method for extracting coal bed gas by negative pressure on the ground through gas-coal simultaneous extraction aiming at a waterless coal bed in an ore field. The extraction of the coal bed gas sequentially comprising three stages, namely pre-extraction before coal mining, extraction during coal mining, and extraction after coal mining; and in the method, in the well drilling process, nonmetal sleeves are descended into an old top section and a coal bed section of a vertical well, steel sleeves are descended in other layers, the nonmetal sleeves arranged in the coal bed section avoid hidden danger of sparkles caused by collision of a coal cutter and metal sleeves in subsequent coal mining, and the nonmetal sleeves arranged in the old top section reserve channels for extraction in a worked out section after the rock and shaft below the old top section are collapsed. In the method for extracting the coal bed gas, one well has three purposes, namely gas is pre-extracted in the coal bed section before coal mining, air return and exhaust are performed in the coal mining process and gas in the worked out section is extracted by negative pressure after coal mining, and the utilization rate of a coal bed gas well is improved; and the gas-coal simultaneous extraction is realized, the safety production of a coal mine is ensured, and multi-win effects of efficiently extracting the coal bed gas, utilizing new energy, protecting environment and the like are achieved.

Description

technical field [0001] The invention relates to a mining method of coal bed methane, in particular to a method for extracting coal bed methane by ground negative pressure extraction of gas-coal co-mining. Background technique [0002] Coal bed methane resources and coal resources are common associated minerals. Only by organically combining the development of coal bed methane and coal mining can the goals of new energy utilization, environmental protection and safe production be achieved. The integrated development mode of coal mining and gas extraction is such a mode of resource efficient exploitation. [0003] At present, there are two modes of coalbed methane exploitation: 1. Surface drilling: using vertical well or directional well technology to exploit coalbed methane resources in the original reservoir. The mechanism of ground drilling and production of coalbed methane is: through drainage and pressure reduction, when the reservoir pressure drops below the critical de...

AI Technical Summary

Problems solved by technology

Generally speaking, the current mode 1 requires large investment, large engineering volume, high investment risk, high technical requirements, and long benefit return cycle, and is only designed for the development and design of coalbed methane before coal mining; mode 2 requires large engineering volume and drainage The time is short (limited by the replacement time of coal mining, coal mining will start within 3-6 months after the construction of the drainage hole), and the coalbed methane mining is only carried out for a very short period of time before coal mining

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