A method for underground coal gasification

Abstract

An underground coal gasification method. The method comprises disposing multiple injection wells (3) and gas collection wells (4) in a gasification operation zone; adding a catalyst and a propping agent into injection wells and gas collection wells by means of a fluid medium; fracturing and reforming the coal layer using a fracturing device to form large areas of fissures and cracks; forming gasification paths in the form of directional wells between the injection wells and gas collection wells; adding a gasification agent, a catalyst, and water through the injection wells to cause coal layer combustions and chemical reactions; collecting at the gas collection wells the gas produced by means of collection devices. The fissure paths between the wells formed by reforming large fractures, and the metal mineral particles used as a propping agent for the paths between wells effectively enable the maintenance of the effective communication in the injection well network for long durations; the metal mineral particles also function as a catalyst and an aggregating agent during gasification, thereby substantially enhancing the coal gasification volume.

Description

technical field [0001] The invention relates to an underground coal gasification method, in particular to a coal seam gasification method at a depth of 500 meters to several thousand meters underground. Background technique [0002] Underground coal gasification is an energy collection method that directly burns underground coal in a controlled manner, generates crude synthesis gas through thermal and chemical effects on coal, and then outputs it to the ground. It is a process that integrates well construction, coal mining, and conversion. The integrated coal development technology is especially suitable for coal seams that cannot be mined or exploited uneconomically by conventional methods, and for secondary or multiple re-mining of coal mines. [0003] The underground coal gasification process requires that the coal seam has a strong gas permeability. However, the natural permeability of the coal seam is very poor, so before the underground coal gasification operation, it...

AI Technical Summary

Problems solved by technology

The catalysts usually selected are mostly alkali metal catalysts, such as potassium carbonate, sodium carbonate, or multi-element alkali metal composite catalysts, such as potassium carbonate-sodium carbonate binary catalyst or potassium carbonate-sodium carbonate-lithium carbonate ternary catalyst. The quantity is large, the cost is high, and a recycling device needs to be installed for recycling, etc.

Images