A method for time difference correction for real-time seismic-while-mining data
金丹
JIN Dan
中煤科工西安研究院(集团)有限公司
随掘地震数据通常采用多台采集分站进行数据采集,各分站拥有多个采集通道,由于井下缺少GPS信号,同时现有的各种网络同步技术受井下网络延迟问题影响,从而使得接收到的随掘数据各分站之间经常会存在同步时差。而时间同步精度直接影响数据的处理及成像质量。因此,随掘地震实时采集数据的同步时差校正对于随掘地震的探测准确性至关重要。
由于当前地面高精度授时系统尚无有效解决井下信号丢失问题的方法,提出了一种基于随掘地震数据的自适应时差校正方法。以各分站独立扫描、综合分析的自适应速度分析方法,解决了各分站的同步时差对速度分析的影响;通过速度分析结果,计算各分站模型道,进而求取得到各分站的同步时差,实现随掘地震数据同步时差的自动校正。
理论模型测试结果表明:该方法所得到的同步时差具有较高精度,并且受噪声影响较小。将其用于煤矿工作面实测随掘地震相干单炮记录,校正后的随掘地震记录各分站之间的时差被消除,且在信噪比较低的各道之间也未受到噪声影响,具有较好的自适应性。地震波传播的时间是随掘记录中的关键属性,通过精确校正时差,确保了各分站记录的随掘数据在时间上的一致性,从而显著提升了数据的准确性。
Seismic-while-mining (SWM) data are usually acquired using multiple stations, each of which is equipped with multiple data acquisition traces. However, the SWM data received by these stations exhibit time differences due to the lack of GPS signals underground and the fact that current network synchronization technologies are confined by network delays underground. Given that the time synchronization accuracy directly affects the quality of data processing and imaging, the time difference correction of real-time SWM data is essential for accurate SWM detection.
Since current high-precision timing systems on the surface suffer from signal loss underground, this study proposed an adaptive time difference correction method based on SWM data. First, using an adaptive velocity analysis method characterized by separate scanning and combined analysis of data from various stations, the impacts of time differences between the stations on the velocity analysis were eliminated. Then, the model seismic traces of various stations were established based on the velocity analysis results. Accordingly, the time differences between the stations were derived, thereby achieving the automatic correction of time differences between SWM data.
The testing results of a theoretical model indicate that the time differences obtained using the new method were highly accurate and scarcely affected by noise. This method was applied to the measured coherent single-shot SWM records of a coal mine’s working face. The application results reveal that the time differences of corrected SWM records between the stations were eliminated. Furthermore, the correction of time differences between various seismic traces with low signal-to-noise ratios was free from noise, demonstrating high adaptability. The travel time of seismic waves is a key attribute in SWM records. The accurate correction of time differences ensures the temporal consistency of the SWM data recorded by various stations, significantly enhancing the data accuracy.
随掘地震时差校正实时采集互相关
seismic-while-mining (SWM);time difference correction;real-time data acquisition;cross correlation
主办单位:煤炭科学研究总院有限公司 中国煤炭学会学术期刊工作委员会