Passage formation method for underground coal gasification

Abstract

A passage formation method for underground coal gasification is provided. The method comprises the following steps of: (a) building a fire area in the bottom coal bed of a first bore hole; (b) performing mechanical and directional drilling operation in a neighbor coal bed close to the bottom of the first bore hole in the vicinity of the fire area through the lower end of a second bore hole which is another existing bore hole or a newly-drilled bore hole outside the fire area, so as to pre-penetrate the neighbor coal bed and thus to form a directional passage communicated with the fire area in the neighbor coal bed; and (c) delivering an oxygen-containing gas to the fire area through the second bore hole and the directional passage, and thermally processing the directional passage to enlarge the directional passage and thus to form a gasification passage used for a underground coal gasification furnace.

Description

technical field [0001] The invention relates to an underground coal gasification penetration method, and the method of the invention is applicable to the fields of underground coal gasification and the like. Background technique [0002] Underground coal gasification technology is to build a gasification furnace directly in the underground coal seam, feed gasification agent, and control the coal gasification reaction underground, so that the coal can be converted into combustible gas in the natural state in situ and transported to the ground process. [0003] The penetration is one of the key steps in the construction process of the underground gasifier. The so-called penetration is the process of artificially constructing a high-permeability channel along the coal seam at the bottom of the gas inlet and outlet drilling holes before the gasification process starts, so as to ensure smooth flow to the coal seam. Supply gasification agent and discharge coal gas from coal seam,...

AI Technical Summary

Problems solved by technology

[0021] As mentioned above, due to the influence of coal seam and formation conditions, the traditional penetration method has technical problems such as short penetration distance, poor channel directionality, and slow penetration speed in practical application. However, the existing directional drilling penetration method can improve the penetration rate. However, there are still problems such as the initial ignition process is easily affected by groundwater, the flame moving speed is slow during thermal processing, and the channel collapse, shrinkage cavity and channel blockage are prone to occur after the channel distance increases.

[0023] Based on the above findings of the inventors, the present invention aims to solve the problem that the initial ignition process in the existing directional drilling penetration method is easily affected by groundwater, the flame moving speed is slow in the thermal processing process, and the hole collapse and shrinkage are prone to occur after the channel distance increases. In order to improve the efficiency and reliability of the penetration process, it provides a method for underground coal gasification penetration process,

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