煤层火成岩侵入的反射波特征研究与应用

Characteristics study and application of coal seam igneous intrusion zones reflected waves

煤田火成岩侵入严重影响矿井的安全高效生产,为此,本文依据岩样测试数据建立煤层火成岩侵入模型,利用高阶有限差分法进行数值模拟,并计算反射波最大振幅和峰值频率参数值.通过对反射波最大振幅和峰值频率的三个主要影响因素:子波峰值频率、火成岩侵入厚度和顶底板岩性参数分析,表明:随着子波峰值频率的增大,反射波的最大振幅和峰值频率均不同程度增大;煤层中火成岩侵入厚度增大,反射波的最大振幅表现为先减小后增大,峰值频率变化为先增大后减小;反射波峰值频率受煤层顶底板岩性参数影响较小,而最大振幅主要受顶板岩性参数影响.此外,分析还发现火成岩薄互层侵入时的反射波最大振幅值较低,峰值频率值较高,并且火成岩不规则侵入会引起反射波不规则、错乱甚至缺失.最后,地震资料和钻孔资料的分析表明正演模拟结果与实际吻合较好.

Though forward modeling the coal seam igneous intrusion which based on measurement data of rock samples by adopting high-order finite difference method,as well as calculating maximum amplitude and peak frequency, we obtained and analyzed the characteristics of reflected waves,for the safety and efficiency mining is seriously influenced by coal seam igneous intrusion.With three main factors of maximum amplitude and peak frequency,which are the peak frequency of wavelet,intrusion thickness of igneous rock and lithologic parameters of roof and floor,being analyzed,the results indicated that maximum amplitude and peak frequency would increase with the peak frequency of wavelet.The maximum amplitude would first decrease and then increase with intrusion thickness of igneous rocks,while the peak frequence changes in contrast.The peak frequency is less affected by lithologic parameters of roof and floor,while maximum amplitude is mainly influenced by lithologic parameters of roof.Moreover,this research also exhibited that the decreasing of maximum amplitude and increasing of dominant frequency may caused by thin interbed intrusion of igneous rocks,as well as irregular intrusion could result in the irregularity,confusion and even missing of reflected waves.Finally,the analysis of seismic recordings and drilling information indicated that forward modeling results were in good agreement with the actual.