基于m序列相关辨识处理压制可控源电磁测深干扰的研究

发布时间：2018-06-05 07:08

本文选题：可控源电磁法 + 伪随机序列　；参考：《中国地质大学(北京)》2015年硕士论文

【摘要】：在实际勘探工作中强干扰的情况在某些情况下大大削弱了可控源电磁勘探方法的有效性,数据质量差,传统去噪方法无法完全解决这一问题。基于伪随机序列相关辨识的方法在其他领域快速发展,已成为提取弱信号、压制强干扰的重要手段。本文着重研究将相关辨识的方法应用到电磁法勘探领域在抗干扰方面的效果。首先通过一个简单的已知系统响应讨论了伪随机序列参数选择的参考标准,即周期长度的选取至少在系统响应持续时间的5倍以上,为了有更好的压制干扰效果,其长度越大越好;码片宽度的选择应与目标频段先结合考虑,期望处理高频段数据则应选择较小的码片宽度,反之则选择较大码片宽度,当目标频带很宽时可选择不同码元的m序列组合使用;重复周期的选择对辨识精度及抗干扰效果影响不大。第三章研究地电模型的一维频域正演及快速余弦变换的时频域转换方法,仿真模拟合成时间序列,证明了相关辨识在辨识一维地电模型脉冲响应及其频谱的可行性、准确性,通过视电阻率曲线表明相关辨识压制周期干扰、随机干扰、脉冲干扰、似放电干扰等不同噪声有良好的效果。在论文第四章中研究可控源电磁法的频域三维正演算法,采用电流密度呈detal函数分布的等效源代替偶极子的存在直接计算总场,在保证了计算稳定性和收敛性的条件下提高计算效率,在地表水平电偶极源的情况验证算法的正确性。最后,模拟生成发射m序列情况下三维模型响应的合成时间序列,加入实际噪声后进行相关辨识获取电磁场频谱,以相关辨识前后数据与理论值之间均方差的度量方式衡量压制干扰的效果,不仅表明相关辨识方法在复杂模型响应的辨识准确,同时也表明其良好的抗干扰效果,借助Wing Link软件反演远区视电阻率及相位数据,在反演断面上直观的展示相关辨识的抗干扰效果。
[Abstract]:Strong interference in practical exploration has greatly weakened the effectiveness of the controllable source electromagnetic exploration method in some cases, and the quality of the data is poor. The traditional denoising method can not completely solve this problem. The fast development of the method based on the correlation identification of pseudo random sequence has become an important part of the extraction of weak signals and the suppression of strong interference. A simple known system response is used to discuss the reference standard for the selection of pseudo random sequence parameters, that is, the selection of the period length is at least 5 times more than the duration of the response time of the system, in order to have better suppression. The greater the interference effect, the greater the better the length, the selection of the width of the chip should be combined with the target band, and the smaller width of the code should be selected, and the larger width of the code is chosen, and the m sequence of different symbols can be selected when the target band is very wide; the selection of the repetition period is to the identification precision and the resistance to dry. The third chapter studies the one-dimensional frequency domain forward modeling and the time-frequency conversion method of the fast cosine transform, simulating the synthetic time series, which proves the feasibility and accuracy of the correlation identification in the identification of the impulse response and the spectrum of the one-dimensional ground electric model, and through the apparent resistivity curve, the correlation identification suppression cycle dry is shown. In the fourth chapter of the paper, we study the three dimensional forward algorithm of the controllable source electromagnetic method in the fourth chapter of the paper, and use the equivalent source of the distribution of the current density to replace the dipole to calculate the total field directly, and to guarantee the stability and convergence of the calculation. High computing efficiency, the correctness of the algorithm is verified by the situation of the surface horizontal dipole source. Finally, the synthetic time series of the three-dimensional model response under the case of launching m sequence is simulated, and the electromagnetic spectrum is obtained after the actual noise is added, and the pressure is measured by the measurement of the mean variance between the data and the theoretical values before and after the correlation. The effect of interference is not only shown that the correlation identification method is accurate in the identification of the response of the complex model, but also shows its good anti-interference effect. The remote area apparent resistivity and phase data are retrieved with the help of Wing Link software, and the anti-interference effect of the related identification is displayed on the inversion section intuitively.
【学位授予单位】：中国地质大学(北京)
【学位级别】：硕士
【学位授予年份】：2015
【分类号】：P631.325

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