黄陵矿区围岩气体成因及致灾机理研究
Study on genetic and destructive mechanism of gas from surrounding rock in Huangling Mining Area
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摘要: 鄂尔多斯盆地南缘黄陵矿区黄陵二号等煤矿在采掘过程中出现井下围岩大量油气异常喷涌现象,导致矿井停采停掘,对矿井的安全生产构成严重威胁。为了揭示黄陵矿区煤层围岩气体来源、运移途径，探讨采掘扰动下灾害发生机理。通过围岩气样地球化学参数测试结果分析，采用烃源岩对比、油型气类型鉴定、数值模拟等方法，结合研究区构造、沉积特征分析，综合采掘扰动效应围岩气灾害诱导作用进行了研究和探讨。研究结果表明：围岩气δ13C2含量平均低于2.88%，结合Schoell关系鉴别图版判识，该围岩气为典型的原油伴生热解类油型气，顶板气中夹有少量煤成气与油型气混合气；其为产于三叠系延长组烃源岩，通过基底构造形成的裂隙通道首次运移至底板围岩，在砂体运移通道及后生裂隙作用下，运移至煤层及顶板围岩的成因机制。采掘扰动效应下，打破原始应力平衡，地应力、构造应力耦合作用下，围岩发生变形和破坏，形成围岩气运移通道，在瓦斯压力催化作用下，加速围岩气异常涌出，导致灾害的发生。Abstract: As the mining process of coal mines (e.g. No.2 Huangling Coal Mine) in Huangling Mining Area along the southern margin of Ordos Basin, a great amount of gas flows comes from the surrounding rocks underground, leading to mining suspension and serious threat to the safe production of coal mines.Based on the geochemistry parameters of gas samples from coal surrounding rock, the geological structure and sedimentary characteristics of Huangling Mining Area.Source rock correlation, identification of oil type gas and numerical simulation methods are used to reveal the source and migration pathway of gas from coal surrounding rock. Further, the mechanism of disaster occurrence under mining disturbance is also discussed. The results show that the gas from coal surrounding rock is a typical oil type gas associated with pyrolysis of crude oil which are discriminated by the average value of δ13C2 is lower than 2.88% and Schoell Plate analysis, the roof gas sandwiched with a small amount of coal gas and oil gas mixture.The genetic mechanism of the gas from coal surrounding rock in the study area is mainly from the source rock of Yanchang Formation, transporting to floor rock at the first with migration pathway of fissure channels formed by basement structures, transporting form bottom to coal seam and roof by the sandstone reservoir and epigenetic fissure providing the secondary migration pathway for the bottom oil type gas.Due to mining disturbance, the balance of original stress and completeness of surrounding rock was broken that formed the transport channels of gas, through these channels, accelerating the abnormal emission happens under the comprehensive catalysis of gas pressure. These factors lead to the occurrence of surrounding rock gas disaster.
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Keywords:
- surrounding rock gas /
- oil type gas /
- mining disturbance /
- genetic mechanism /
- disaster
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