發(fā)布時間：2018-06-05 07:08

  本文選題：可控源電磁法 + 偽隨機序列　； 參考：《中國地質(zhì)大學(北京)》2015年碩士論文

【摘要】：在實際勘探工作中強干擾的情況在某些情況下大大削弱了可控源電磁勘探方法的有效性,數(shù)據(jù)質(zhì)量差,傳統(tǒng)去噪方法無法完全解決這一問題�；趥坞S機序列相關辨識的方法在其他領域快速發(fā)展,已成為提取弱信號、壓制強干擾的重要手段。本文著重研究將相關辨識的方法應用到電磁法勘探領域在抗干擾方面的效果。首先通過一個簡單的已知系統(tǒng)響應討論了偽隨機序列參數(shù)選擇的參考標準,即周期長度的選取至少在系統(tǒng)響應持續(xù)時間的5倍以上,為了有更好的壓制干擾效果,其長度越大越好;碼片寬度的選擇應與目標頻段先結(jié)合考慮,期望處理高頻段數(shù)據(jù)則應選擇較小的碼片寬度,反之則選擇較大碼片寬度,當目標頻帶很寬時可選擇不同碼元的m序列組合使用;重復周期的選擇對辨識精度及抗干擾效果影響不大。第三章研究地電模型的一維頻域正演及快速余弦變換的時頻域轉(zhuǎn)換方法,仿真模擬合成時間序列,證明了相關辨識在辨識一維地電模型脈沖響應及其頻譜的可行性、準確性,通過視電阻率曲線表明相關辨識壓制周期干擾、隨機干擾、脈沖干擾、似放電干擾等不同噪聲有良好的效果。在論文第四章中研究可控源電磁法的頻域三維正演算法,采用電流密度呈detal函數(shù)分布的等效源代替偶極子的存在直接計算總場,在保證了計算穩(wěn)定性和收斂性的條件下提高計算效率,在地表水平電偶極源的情況驗證算法的正確性。最后,模擬生成發(fā)射m序列情況下三維模型響應的合成時間序列,加入實際噪聲后進行相關辨識獲取電磁場頻譜,以相關辨識前后數(shù)據(jù)與理論值之間均方差的度量方式衡量壓制干擾的效果,不僅表明相關辨識方法在復雜模型響應的辨識準確,同時也表明其良好的抗干擾效果,借助Wing Link軟件反演遠區(qū)視電阻率及相位數(shù)據(jù),在反演斷面上直觀的展示相關辨識的抗干擾效果。
[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.
【學位授予單位】：中國地質(zhì)大學(北京)
【學位級別】：碩士
【學位授予年份】：2015
【分類號】：P631.325

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本文編號：1981103