煤火区多层梯度烧变岩磁异常正演研究

针对煤田火灾发展过程中地磁异常变化特性进行研究。根据自燃煤层过火顶板内传热特性建立了多层梯度烧变地质模型,结合烧变围岩热磁性质建立了煤火二维非均质地层磁异常正演模型。模拟了不同条件下煤火地层局部磁异常剖面,分析了顶板岩性、烧变热特性及燃烧煤层深度对地磁异常的影响。比较结果表明:不同岩性烧变地层的磁异常差异显著,磁异常强度随自燃中心温度升高非线性增加,而深部煤层燃烧产生磁异常强度远小于浅部煤火。

Forward Modeling for Magnetic Anomaly of Multilayer Burnt Rocks in Coal Fire Area

This paper focus on the geomagnetic anomaly characteristics of coal fire development process. According to the heat transfer properties in burned roof, the multilayer gradient burnt stratum structure was established. A forward model of magnetic anomaly of two-dimensional heterogeneous coal fire stratum was developed combined with the thermal-magnetic properties of burnt rocks. Local magnetic anomaly profiles of coal fire stratum under different conditions were simulated and the influences of lithology, burnt thermal characteristics and combustion coal seam depth were analysis. The results show that: There exits significant differences of magnetic anomalies between different lithology burnt stratums. The magnetic anomaly intensity increases nonlinearly when center temperature of spontaneous combustion rises, while the magnetic anomaly caused by deep combustion coal seam is far less than the shallow coal fire.