大城勘查区煤层的煤级特征及煤变质成因分析

Analysis of Coal Rank Characteristics and Coal Metamorphism in Dacheng Exploration Area

研究单一煤层和煤系地层煤级参数随埋深的演化,显示单一煤层煤级参数与煤层埋深相关性很低,离散度较高;同一勘查线上,靠近东部边界钻孔单位深度内煤层挥发分产率下降的速率大,变质程度高;不同勘查线数据对比显示,北部变质程度更高。结合区域重力场和航磁异常平面等值线图,发现煤层在受深成变质作用仅达到气煤阶段的基础上,又叠加了沿着断裂面上传到上部地层的隐伏岩体热量,地温梯度发生改变,使煤层变质程度增高。

Studied the change of coal rank parameters with the depth for single coal seam and the coal-bearing stratum. The results showed that： the correlation between coal rank parameters and the depth was low of a single seam, and high dispersion; coal volatile of unit depth decline rate was higher close to eastern border drillings in the same exploration line, and high ranks; along the eastern border to north found that the outside influence was increased. By analyzing the gravitational field and the plane contour map of aeromagnetic anomalies of coalfield area, it was found that coal seam reached to gas coal by plutanic metamorphism, and later was superimposed by buried rock heat which along the fracture surface spread to upper stratum, and changed geothermal gradient, resulting in the degree of metamorphism increased.