DOI: 10.11799/ce202503019
Initial gas emission characteristics of borehole drilling in heterogeneous coal seams
LIN Huaying
TIAN Shixiang
JIAO Anjun
SONG Kai
XU Shiqing
XIE Hongfei
HENG Xianwei
Abstract：In order to examine the divergence in initial gas emission patterns between homogeneous and heterogeneous coal seams during borehole drilling operations.Through numerical simulations using COMSOL Multiphysics and experimental validation via a coal seam analog apparatus equipped with continuous-flow measurement systems,three distinct drilling scenarios were monitored to delineate the spatiotemporal evolution of gas emissions relative to drilling depth.Key findings reveal:Gas velocity within fracture zones exhibits a 19-fold amplification compared to baseline flow rates,with emissions predominantly localized at the drill bit interface before attenuating sharply(t≈2 s post-exposure);A monotonically increasing correlation exists between cumulative drilling penetration depth and initial gas emission flux,though emission growth rates demonstrate asymptotic decay characteristics over time-a phenomenon corroborated through field validations at Haizi Coal Mine and Weixu Coal Mine;Experimental measurements using HSBC coal specimens in heterogeneous strata(characterized by soft coal inclusions within hard matrices)identify anomalous emission peaks reaching 2.96 baseline values,aligning with numerical predictions and confirming the parameter's diagnostic sensitivity to coal seam heterogeneity.
Keywords：heterogeneous coal seamsinitial gas emissioncontinuous-flow quantificationnumerical simulation
Publication Date：2025-03-20
Online Publishing Date：2025-08-15(First online date of this platform, not the publication date of the document)
Pages：7( 143-149 )