高瓦斯煤层间岩巷瓦斯异常区物探及化探探查

在高瓦斯煤层间掘进的岩巷,有时会揭示局部瓦斯异常区,导致岩巷内瓦斯含量突然升高甚至出现瓦斯超限现象。瓦斯异常区通常为相对无水裂隙区,与周围岩层相比存在电阻率、波阻抗等物性差异,适合采用地球物理勘探手段探查其赋存范围;同时瓦斯气源主要产自煤的形成和变质过程,因此不同煤层的瓦斯具有不同的地球化学特征,特别是碳同位素比值差异明显,适合采用地球化学手段确定瓦斯气源。淮南矿业集团谢桥矿1252(3)工作面底抽巷位于两个高瓦斯煤层中间,在巷道掘进过程中,迎头段锚杆孔涌出大量瓦斯,导致巷道瓦斯超限。依据瓦斯异常区在三维电阻率剖面上表现为较高视电阻率值,在地震反射波时间剖面上表现为相位错动及长尾状波形等特征,确定了气源裂隙带的发育方向为底抽巷顶板至13-1煤层,并圈定了异常范围。通过对岩巷瓦斯异常区、13-1煤、11-2煤层的瓦斯气样进行地球化学分析,发现瓦斯异常区中碳同位素δ13C与13-1煤层具有很高的相似度,即认为该瓦斯异常主要来源于13-1煤层;另外地球化学分析结果表明利用气体组份不易区分来源煤层。

Geophysical and Geochemical Prospecting for Hard Heading Gas Abnormal Places between High Gas Coal Seams

Hard heading driving between high gas coal seams may reveal local gas abnormal places sometimes, and can cause gas content in hard heading rising abruptly and even out of gauge. The gas abnormal places are usually dry fissure areas with different physical properties of resistivity and wave impedance in comparison to peripheral strata, thus is propitious to geophysical means to delineate their occurrence ranges; also because of gas source mainly produced from coal formation and metamorphic processes have made gas from different coal seams with different geochemical characteristics, especially apparent differences in carbon isotopic proportion, thus propitious to geochemical means to determine gas sources. On the basis of gas anomaly usually appears as higher resistivity values on the 3D resistivity section, and appears as phase dislocation and long tailed waveform on the seismic reflection time section characteristics have determined development orientation of gas source fissure zone is within bed plate tunnel roof to coal No.13-1, also delineated its anomalous range. Through geochemical analysis of hard heading gas abnormal places, gas samples from coal Nos.13-1 and 11-2have found carbon isotope δ^13C in gas abnormal place and in coal No.13-1 has high similarity, thus can consider that the gas anomaly mainly from coal No.13-1. Besides, the geochemical analysis result has shown that using only gas constituents is not easy to differentiate source coal seam.