煤层厚度地震槽波层析成像分辨率分析

Resolution analysis of in-seam seismic tomographic inversion for coal thickness

透射法地震槽波勘探技术依据不同煤厚槽波频散特征差异,利用敏感频率下槽波走时层析成像算法反演得到煤层槽波速度,进而预测煤层厚度分布.层析反演结果的准确性直接影响煤厚探测的精度,反演得到小异常体常被错误地当作高精细度的体现.槽波层析反演分辨率是衡量反演结果精细程度的重要指标,决定了反演结果的可靠程度,但对于槽波分辨率的估算缺乏有效的技术手段.通过对比分析理论模型、棋盘格模型、射线密度和统计分辨率等方法,探讨这些分辨率分析方法的优缺点.根据义马11061工作面层析成像结果以及后期实际煤厚揭露数据,验证了槽波勘探方法的合理性和准确,认为采用巷帮煤厚作为约束条件,可提高层析成像分辨率,采用统计分辨率方法对反演结果分析较为实用.

Based on the difference of dispersion characteristics of different coal thicknesses, in-seam seismic technology with transmission method can obtain channel wave velocity of coal seam by inversion of traveltime tomography algorithm in the sensitive frequency,then the coal thickness distribution is predicted. The accuracy of tomographic inversion results directly affects coal thickness detection. Small anomaly of inversion is often mistaken as a high degree of precision. The resolution of channel wave tomographic inversion is an important index to measure result degree,which determines the reliability of the inversion,but lacks effective technical methods to estimate the results. The advantages and disadvantages of these resolution analysis methods are discussed by comparing theoretical model,checkerboard model,ray density and statistical resolution. According to the results of tomography of Yima 11061 working face and the actual coal thickness data,the rationality and accuracy of channle wave exploration technology is verified. It is believed that adopting coal thickness in the side wall of roadway as constraint condition can improve the resolution of tomographic inversion,and the statistical resolution method is more practical than the others.