川南煤田象顶井田瓦斯赋存特征及影响因素

根据象顶井田大量瓦斯实测资料分析,区内瓦斯含量高分带不明显,沼气带在埋深100m以下,瓦斯含量有随埋深增加而增大的趋势,但相关性不显著,地质构造及水文条件是影响区内瓦斯分布的主要因素。井田内先期发育的压性层间滑动断层(f701)及其派生断层纵贯全区,导致构造煤发育,瓦斯含量高;中部及西南部的F39、F418、F428、F405张性正断层切割了先期的压性断层,断层破碎带及裂隙为瓦斯逸散提供了通道,同时断层使上盘煤层与下盘岩溶发育的茅口灰岩直接接触,加速了瓦斯的逸散,致使该区域内煤层瓦斯含量降低,形成了井田北东部瓦斯含量高、中部及南西部含量相对较低的格局。根据煤体结构、构造分布、煤层特征,预测区内C19煤层易发生突出区域位于井田北东部。

Gas Hosting Features and Impacting Factors in Xiangding Minefield,Southern Sichuan Coalfield

According to the analysis of large amount measured gas data in the Xiangding minefield,gas content is high in the area,but no obvious zoning.Buried depth of methane zone is below 100m depth,gas content has a trend of increasing with buried depth,but no obvious dependency.Geological structures and hydrogeological conditions are main factors to impact gas distribution in the area.Earlier developed compressional interlayer gliding fault F701 and its derived faults developed north to south in the whole area causing developed deformed coal and high gas content.Tensional faults F39,F418,F428 and F405 in middle and southwest parts have cut earlier compressional faults,thus the shattered fault zone provides channels for gas effusion.Meanwhile,faults make direct contact of upper plate coal seams with karst developed Maokou Formation limestone and accelerate gas effusion,bring about gas content of coal seams in the area lowering,form the pattern of high gas content in northeastern minefield and relatively low in middle and southwestern parts.According to coal mass configuration,structural distribution,coal seam features have predicted the C19 coal seam easy to out-burst area is in northeastern part of the minefield.