Coal seam underground gasification development method and dual horizontal well group

Abstract

The application discloses a coal seam underground gasification development method and a double horizontal well group. The method comprises the following steps: drilling a double horizontal well group comprising a horizontal injection well and a horizontal production well in a coal seam, the horizontal sections of the injection well and the production well are located at the same depth and the same direction of the coal seam and are drilled oppositely, the distance between the toe of the horizontal section of the injection well and the toe of the horizontal section of the production well satisfies a set distance condition; determining an initial injection point and a sealing point according to the position of the toe of the injection well and the position of the toe of the production well respectively, injecting a gasification agent into the injection point through the injection well and igniting the coal seam, and the sealing point gradually retreats in the process of increasing the first gasification cavity formed until the sealing point disappears; gradually retreating the injection point to the direction of the injection well until a plurality of continuous gasification cavities are formed. The method solves the problem of poor interwell permeability of the medium-deep coal seam by using the double controllable retreat technology through the double horizontal well, and finally effectively improves the gas production effect.

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