基于模拟退火法的磁共振测深多源谐波噪声压制方法

Suppression method of multi-source harmonic noise in magnetic resonance sounding based on simulated annealing method

磁共振测深找水方法在高电磁噪声环境下应用时,往往会因为电磁噪声的干扰导致实测数据信噪比降低,反演结果难以准确地确定实际地下水体的分布状况,降低方法的应用效果。针对磁共振测深找水方法在实际野外数据采集工作中常面临的多源谐波噪声干扰问题,在模型去噪的基础上推导出网格搜索同步删除法,进一步提出了效率更高的模拟退火同步删除法。仿真结果表明,2种方法均能有效压制多源谐波噪声,而模拟退火同步删除法能够更快速地搜索谐波基频值,相较网格搜索同步删除法在双基频谐波情况下工作效率提高2.35倍,大大降低了去噪流程的时间成本,且对多源谐波噪声也能取得较好的去噪效果。将该去噪算法应用于实例中,反演结果和钻孔资料的对比表明,模拟退火同步删除法可以有效压制磁共振测深方法实测数据中的多源谐波噪声,显著提高磁共振测深方法的应用效果。

When the magnetic resonance sounding(MRS)method is applied in an environment with high electromagnetic noise,the signal-to-noise ratio of the measured data is often reduced due to the interference of electromagnetic noise.As a result,it is difficult to accurately determine the aquifer distribution using the inversion results,thus reducing the application effects of the method.In this paper,aiming at the common problem of multi-source harmonic noise interference in the field data acquisition using the MRS method,this paper derives the grid search simultaneous removal method based on the model denoising and further proposes the more efficient simulated annealing simultaneous removal method.The simulation results show that both methods can effectively suppress multi-source harmonic noise.Compared with the grid search simultaneous removal method,the efficiency of the simulated annealing simultaneous removal method is improved by 2.35 times in the case of double fundamental frequency harmonics,which greatly reduces the time cost of the denoising process.Meanwhile,the simulated annealing simultaneous removal method allows for great denoising effects of multi-source harmonic noise.Finally,the proposed denoising algorithm was applied to a field example.The comparison of the inversion results and borehole data shows that the simulated annealing simultaneous removal method can effectively suppress the multi-source harmonic noise in the measured data obtained using the MRS method and can significantly improve the application effects of the method.