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近水平厚煤层微震垂向定位优化及实践

Optimization and field practice of microseismic vertical positioning in near-level horizontal thick coal seams

  • 摘要: 为提高微震系统在近水平厚煤层中垂向定位精度,设计通过安装深孔检波器提高微震台站间高差的方案,对近水平厚煤层中微震系统台站空间布设进行优化;采用数值仿真模拟结合工程试验的方法,研究了深孔检波器的安装对提高震源垂向定位精度的理论可行性,并通过现场实践进行了验证。数值仿真模拟结果表明:通过提高台站Z坐标,可以有效减小该台站附近的垂向定位误差。现场实践结果表明:深孔检波器安装后,煤层事件频次和微震能量的接收占比分别提高了10.42个百分点和6.64个百分点,顶板事件频次和微震能量的接收占比分别提高了11.58个百分点和12.73个百分点;对同一事件定位结果进行对比,深孔检波器在参与事件定位时,顶板事件垂向高度提高,平均提高36.61 m,最大升高92.64 m;微震能量也存在增大的情况,平均增大1 903.44 J,微震能量最大提高9 457.39 J;对同一事件的波形进行对比,深孔检波器与邻近的顶板检波器接收到的振动波存在有效到时差。通过安装深孔检波器,有效提高了微震系统对顶板事件的垂向定位精度,为近水平煤层微震台网布设优化提供了指导。

     

    Abstract: In order to improve the vertical positioning accuracy of the microseismic system in the near-level horizontal thick coal seam, a scheme was designed to increase the height difference between the microseismic stations by installing the deep hole detector, and the space layout of the microseismic system station in the near horizontal thick coal seam was optimized; the numerical simulation of the optimal design theory combined with the engineering experiment method was carried out to study the theoretical feasibility of the installation of the deep hole geophone to improve the vertical positioning accuracy of the source, and it was verified by field practice. The numerical simulation results show that by increasing the Z coordinate of the station, the vertical positioning error in the vicinity of the station can be effectively improved. The field practice results show that the frequency of coal seam events and the proportion of microseismic energy received after the installation of the deep hole geophone increased by 10.42 percentage points and 6.64 percentage points, respectively. The frequency of roof events and the proportion of microseismic energy received increased by 11.58 percentage points and 12.73 percentage points respectively. Comparing the results of the same event, the deep hole detector was involved in event location, and the top event was vertical. The height is increased by 36.61 m and the maximum height is 92.64 m.The microseismic energy is also increased, with an average increase of 1 903.44 J and the maximum increase of the microseismic energy is increased by 9 457.39 J. The waveforms of the same event are compared, the deep hole detector is compared with the vibration waves received by the neighboring detectors are effective to the time difference. The installation of deep-hole geophones effectively improves the vertical positioning accuracy of the microseismic system for roof events, and provides guidance for the optimization of the microseismic network layout in the near-level coal seam.

     

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