DOI: 10.11799/ce202502015
Deep directional borehole"drilling-punching-protection"technology for permeability enhancement in gas extraction of soft coal seam
LI Gaojian
LI Haitao
Abstract：In order to achieve accurate,efficient and stable gas extraction in soft coal seams,in view of the problems of large drift of deep borehole drilling trajectory in soft coal seams,low permeability,poor extraction effect,and high scrapping rate of boreholes that are easy to collapse,deep directional borehole"drilling-punching-protection"technology for permeability enhancement in gas extraction of soft coal seam was proposed.The technology realizes the directional drilling through combining the sliding drilling and composite drilling,changes the stress environment of the coal body through the hydraulic punching to enhance permeability and promote extraction,and provides a certain support for the borehole wall through the screen tube protection technology to ensure gas extraction channel.Engineering practice shows that:in the soft coal seam using the proposed technology,and the maximum total footage of single borehole reaches 1942 m,which lays the foundation for accurate extraction;the longest stable extraction duration exceeds 450 days,the cumulative amount of gas extracted through one borehole exceeds 100000 m3,and the borehole protection rate reaches a maximum of 92.6%,realizing the borehole protection of the entire borehole section.The problems of inaccurate extraction area,poor extraction effect and low efficiency in soft coal seams were solved,realizing precise,efficient and stable gas extraction from deep boreholes in soft coal seams.
Keywords：directional drillinghydraulic permeability enhancementscreen pipe protectionpermeability enhancement of coal seamgas extraction promotion
Publication Date：2025-02-28
Online Publishing Date：2025-08-15(First online date of this platform, not the publication date of the document)
Pages：9( 103-111 )