基于自适应滤波的海洋可控源数据噪声处理方法研究

发布时间：2018-03-06 17:04

本文选题：海洋可控源电磁法　切入点：距离因子　出处：《中国地质大学》2017年博士论文　论文类型：学位论文

【摘要】：海洋可控源电磁方法(MCSEM-Marine Controlled Source Electromagnetic Method)技术,是基于海底储层和围岩之间的电阻率差异为物性基础的一种频率域电磁方法,其优点是对海底高阻储层反应灵敏,同时也是储层评价的重要方法。目前,在拖曳工作模式中,发射机被拖于距离海底以上沿测线移动,而接收机固定于海底进行信号接收,由于海底环境复杂,接收机接收到的信号中不同程度会含有噪声的干扰,这严重影响了资料解释的精度和可信度,有必要在MCSEM数据处理中开展信号去噪工作。本文详细推导了海洋可控源电偶源在不同地电模型上的电磁响应,并对不同的地电模型上的电磁响应做了分析讨论,同时推导了层状大地海洋电磁的一维理论计算公式,使用该算法对海洋电磁信号响应进行了分析。基于理论模型计算了海洋可控源电磁场的MVO响应,分析MVO曲线上所包含的地质信息。建立了M1d理论计算模型,使用推导的正演理论公式计算了不同参数下海洋电磁模型的响应曲线,并分析了其特征。通过改变模型参数,详细研究了海洋电磁发射机姿态、发射频率对海洋电磁信号响应的影响,同时研究了海底储层流体电性、海水深度对海洋可控源电磁信号的影响。数据去噪的目的是尽可能的恢复原始数据特征,通过各种方法技术滤除噪声信号,保留信号原有信息,为资料的进一步解释提供可靠的数据依据。现有的去噪算法都是基于传统的方法技术,数据的去噪效果对输入的参数依赖性较大,极大的限制了MCSEM数据去噪的效果。本文在分析了海洋电磁信号噪声的来源和类型,并针对信号中的随机噪声开展去噪研究。海洋是一个低通滤波器,所有的高频人文噪声将不会对海洋电磁信号造成干扰,其中空气波的影响主要对浅海电磁勘探有较大的影响,而对于深海空气波的干扰主要在大收发距的远区,所以通过选择合适的收发距来有效地减小空气波的干扰。首次把在通信工程中大量使用的自适应滤波技术引入海洋电磁信号噪声处理中,详细推导了自适应滤波技术的理论公式,并针对LMS自适应算法展开详细研究,在LMS自适应滤波算法中,步长因子极大的影响了LMS算法的收敛速度和失调性,大的步长因子可以加速系统的收敛速度,但是过大的步长因子又会使系统出现混乱、失调现象。而过小的步长因子虽然能保证系统稳定收敛,但会影响系统的收敛速度,极大的增加了系统代价。而滤波器的阶数也同样会影响系统的滤波效果,大的滤波器阶数可以提高去噪质量,但同时增加了系统的开销,为此,本文在分析了定步长LMS自适应滤波算法的优缺点之后,结合MCSEM数据随偏移距变化的特征,提出了一种新的基于距离因子调节的变步长DLMS算法,该算法能较好地兼顾系统收敛速度和稳态误差,改善了现有算法的收敛速度和失调性问题。使用DLMS算法对理论模型和实测数据进行处理,通过大量的仿真算例的去噪研究表明该算法对压制系统中的随机信号非常有效,在此研究基础上,把该算法应用到海洋电磁信号的去噪过程中,通过理论模型和实测数据的去噪研究,结果表明该算法提高了迭代的收敛速度,同时保持了系统的平稳性,能够使MVO曲线和视电阻率曲线的特征和细节得到有效恢复,证明该方法可以用于海洋电磁信号的实际去噪处理中,为海洋电磁数据的去噪研究提供了新的研究思路,拓展了海洋电磁数据噪声压制的新方法,为后续的海洋电磁数据处理和资料解释提供了一种有效的数据处理手段。在以上研究的基础上开展了基于.Net框架的海洋电磁数据噪声处理模块的开发,该模块具有数据的基本管理、预处理,噪声压制和一维的正反演功能,并可以在可视化界面下建立正演模型数据,极大的提高了程序模块的易用性。
[Abstract]:Marine controlled source electromagnetic method (MCSEM-Marine Controlled Source Electromagnetic Method) technology, is the difference between the reservoir resistivity and rock based on the physical basis of a frequency domain electromagnetic method, the utility model has the advantages of high resistivity seabed reservoir sensitive reaction, but also is an important method for reservoir evaluation. At present, in the towing work mode, the transmitter is dragging on the distance above the sea floor along the line of mobile, fixed on the seabed and the receiver signal receiving, due to complex seabed environment, different degree of interference with noise signal received by the receiver, which seriously affected the interpretation precision and reliability, it is necessary to carry out the signal in the MCSEM data processing to noise. This paper presents the electromagnetic marine controlled source electric dipole source in different geoelectric model and the electromagnetic response of geoelectric model on different response analysis At the same time, discussion, calculation formula of one-dimensional theory of marine electromagnetic layered earth is deduced using the algorithm of marine electromagnetic signal response is analyzed. The marine controlled source electromagnetic MVO response was calculated based on the theoretical model, the analysis of geological information contained in the MVO curve. The calculation model is established using the M1d theory, deduced the forward theoretical formula the response curve of marine electromagnetic model under different parameters is calculated, and the analysis of its characteristics. By changing the parameters of the model, a detailed study of the marine electromagnetic transmitter attitude, transmitting frequency effect on marine electromagnetic signal response, at the same time on the seabed reservoir fluid power, effect of water depth on the marine controlled source electromagnetic signal to the data. The purpose of noise is as far as possible to restore the original data characteristics, through a variety of techniques to remove the noise and preserve the original information signal, a step for data interpretation. To provide reliable data. On the basis of the existing denoising algorithms are based on the traditional method of denoising effect on data input parameter dependence is larger, greatly limits the MCSEM data denoising effect. Based on the analysis of the sources and types of marine electromagnetic signal noise, and random noise in the signal to carry out research on denoising. The ocean is a low pass filter, high frequency noise will not cause all human disturbance to the marine electromagnetic signal, the effect of air wave of shallow water electromagnetic exploration has great influence, and for the deep sea air wave interference in the transmitter receiver distance far, so by choosing appropriate offsets to effectively reduce the interference of air wave. The adaptive filtering technique is widely used in communication engineering application are introduced to deal with the noise of the marine electromagnetic signal, deduced the adaptive filtering technology science The formula, and detailed research on LMS adaptive algorithm in LMS adaptive filtering algorithm, the step factor has a great impact on the convergence speed of LMS algorithm and the offset of the step factor can accelerate the convergence speed of the system, but a big step factor will make the system chaos, disorder and phenomenon. Small step factor can ensure the stability of the system convergence, but the convergence rate of the system, greatly increasing the cost of the system. And the order of the filter will also affect the filtering effect of the system, the order of the filter can improve the denoising quality, but also increase the cost of the system, therefore, in this paper analyzes the advantages and disadvantages of the fixed step size LMS adaptive filtering algorithm, combining with the characteristics of MCSEM data changes with the offset distance, proposes a variable step size DLMS algorithm based on the new regulation factor, the algorithm can better Take into account the convergence speed and steady-state error, improve the convergence speed of the existing algorithm and offset problem. Using DLMS algorithm to process the theoretical model and measured data, through a lot of simulation results of denoising results show that the algorithm is very effective to suppress the random signal in the system, on the basis of this research, the application of the algorithm the marine electromagnetic signal denoising process, the denoising of the theoretical model and experimental data, the results show that the algorithm improves the convergence rate, while maintaining the stability of the system, can make the MVO curve and the features and details of the apparent resistivity curve can be effectively restored, prove that the method can be used in actual marine electromagnetic signal denoising process, which provides a new method for denoising of marine electromagnetic data, develops a new method of noise suppression of marine electromagnetic data, for the subsequent sea Ocean electromagnetic data processing and data interpretation provides an effective means of data processing. Based on the above research carried out on the development of marine electromagnetic noise data processing module based on.Net framework, the module has the basic management, data preprocessing, and noise suppression and one-dimensional speech function, and forward model the data in the visual interface, which greatly improves the usability of program modules.

【学位授予单位】：中国地质大学
【学位级别】：博士
【学位授予年份】：2017
【分类号】：P631.325

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