基于瞬变电磁法的煤层风氧化带探查

    Exploring coal seam wind oxidation zone based on transient electromagnetic method

    • 摘要: 煤层风氧化带的发育对煤矿的生产组织和安全回采影响巨大,针对准格尔煤田东部隆起带煤层风氧化带圈定的技术难题,研究了瞬变电磁法探查煤层风氧化带的可行性。首先对研究区正常地层与煤层风氧化区的电阻率测井曲线进行了分析,总结了正常区与煤层风氧化区的电性差异,并以电阻率测井曲线构建了煤层风氧化区地电模型;然后采用MAXWELL软件对理论模型的瞬变电磁响应进行了数值模拟,发现在煤层风氧化区瞬变电磁反演电阻率断面表现为浅部低阻层变厚、低阻异常幅值减小的异常特征,可以以此来圈定煤层风氧化区的分布范围;最后在数值模拟的基础上,在串草圪旦煤矿开展了现场试验,结合钻探情况对试验数据从瞬变电磁反演电阻率断面和平面2个角度进行了分析,结果表明瞬变电磁法探测划分风氧化带是可行的。

       

      Abstract: The development of coal seam wind oxidation zone has a huge impact on the production organization and safe mining of coal mines. This paper focuses on the technical difficulties in delineating the coal seam wind oxidation zone in the eastern uplift zone of Junggar Coalfield, and studies the feasibility of using transient electromagnetic method to explore the coal seam wind oxidation zone. Firstly, the electrical resistivity logging curves of normal strata and coal seam wind oxidation areas in the research area were analyzed, and the differences in electrical properties between normal areas and coal seam wind oxidation areas were summarized. A geoelectric model of coal seam wind oxidation areas was constructed based on the electrical resistivity logging curves; then, MAXWELL software was used to numerically simulate the transient electromagnetic response of the theoretical model. It was found that the resistivity cross-section of the transient electromagnetic inversion in the coal seam wind oxidation zone exhibited abnormal characteristics of shallow low resistance layer thickening and reduced low resistance anomaly amplitude, which can be used to delineate the distribution range of the coal seam wind oxidation zone; finally, based on numerical simulation, on-site experiments were conducted in the Chuancao Gedan Coal Mine. Combined with drilling conditions, the experimental data were analyzed from the perspectives of transient electromagnetic inversion resistivity cross-section and plane. The results showed that the transient electromagnetic method is feasible for detecting and dividing wind oxidation zones.

       

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