Ultra thick seam underground gasification method

Abstract

The invention discloses an ultra thick seam underground gasification method. By adopting a way of combining vertical wells with horizontal wells, a way of gas injection by the vertical wells and production by the horizontal wells is adopted first and then the way of gas injection by the vertical wells and production by the horizontal wells is converted into a way of gas injection by the horizontalwells and production by the vertical wells after a cavity of a certain scale is formed. The seam is developed longitudinally by means of overlapping action of gas effectively, and a burning front edge is kept nearby the horizontal wells. The method is an effective method of gasifying a deep seam, the thickness of which is greater than above 30 m, so that the complexity of operation is reduced effectively, the production efficiency of the seam is improved and the employing effect and the gasification effect of the deep seam are improved.

Description

technical field [0001] The invention belongs to the technical field of coal seam development, and in particular relates to an underground gasification method for extremely thick coal seams. Background technique [0002] Underground coal gasification technology (Underground Coal Gasification, UCG) is also called in-situ coal gasification. Separation, fixed carbon, etc.) are transformed into combustible gases through physical and chemical transformations such as pyrolysis, combustion, and gasification. UCG combines the three major processes of well construction, coal mining and gasification into one, which has the advantages of low gas production cost, high safety and good environmental benefits. The cost of coal gas produced by UCG is only 25% to 50% of the gasification of the surface gasifier. It can be used as raw material gas for gas-fired power generation, boiler fuel, and synthetic chemical products, significantly reducing the cost of power generation or synthetic chemi...

AI Technical Summary

Problems solved by technology

The disadvantages of this gasification furnace construction process are that the penetration speed is slow, the penetration direction is poor, and the penetration is difficult or impossible when the vertical well spacing is large; Without a gas injection device, the gasification agent diffuses and burns throughout the gasifier, resulting in ineffective control of the combustion range and boundary, resulting in low gas quality; the expanded combustion range leads to large-scale collapse of the overlying rock, and poor stability control of the surrounding rock

[0008] Since the 1970s and 1980s, European and American countries represented by the United States have mainly developed the wellless CRIP process. In terms of gas injection control, a tube-type mobile gas injection point device is used to periodically retreat and pull the gas injection point. Each time the gas injection point is moved back a certain distance, this process requires a large-scale gas injection elbow spiral pulling device on the ground, which requires high equipment investment and complicated process operations. It is difficult to seal the gas injection elbow at the ground end. When the coal seam is buried deep When the value is large, the operational reliability of the mobile gas injection device is reduced due to the influence of geological stress and borehole deformation

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