基于三元伪随机编码的冲击夯可控震源技术研究

发布时间：2018-06-02 07:22

本文选题：冲击夯可控震源 + 三元伪随机编码　；参考：《吉林大学》2017年硕士论文

【摘要】：在一些环境敏感地区比如城市以及复杂山区的地质勘查和矿产资源勘探中,车载式可控震源体积大,在复杂地形下移动不方便,难以开展地震勘探工作。目前我国的矿产资源多处于山区,地形复杂,交通不方便。而冲击夯可控震源作为一种体积小,质量轻,移动方便而且输出力大的一种可控震源在上述地区进行地质勘查发挥着极大的优势。在冲击夯可控震源的研究中,高分辨率和高信噪比一直是备受关注的热点问题,也是亟需解决的问题。传统的冲击夯可控震源控制方式中,在冲击夯连续冲击时,由于振动信号是周期性的,使得相关解码记录中存在着严重的相关干扰,旁瓣效应非常严重。相比于传统的控制方式,改进的二元伪随机编码控制方式,减小了相关干扰,但是二元伪随机编码的自相关函数存在着旁瓣效应,制约了地震记录的分辨率和信噪比的提高。本文针对上述控制方法中存在的问题,提出了基于三元伪随机编码的冲击夯可控震源控制方法,并设计了激励信号发生器,进行野外实验,证明了该方法的有效性。首先研究了三元伪随机编码技术以及编码序列生成原理。通过对三元伪随机编码自相关的分析,结果表明三元伪随机编码的自相关函数无旁瓣效应,类似于完美的脉冲函数。其次详细的介绍了三元伪随机编码技术在冲击夯可控震源控制中的应用,提出编码匹配原则,每一种编码对应于冲击夯的不同振动状态。根据编码匹配原则,设计了激励信号发生器,实现冲击夯可控震源的编码控制方式。并针对冲击夯可控震源的机械特性,导致一些信号不能正确输出的缺点,在控制过程中加入了反馈控制模块,利用传感器采集基板上的震动信号,实时检测冲击夯可控震源输出信号的正确性。软硬结合实现了冲击夯可控震源的三元伪随机编码控制,为冲击夯可控震源技术的发展提供了新的方向。最后进行了实际实验。首先,通过对比验证采集的震动信号和编码序列对应的振动信号的一致性,确定激励信号发生器可以正确发出控制信号;其次,对比了通过二元伪随机控制方法和三元伪随机编码控制方法下采集得到的相关地震记录,实验结果表明三元伪随机编码控制方法得到的相关地震记录相关干扰明显减少;自相关结果中主瓣和旁瓣的比值明显提升,提高了信噪比;在频谱分析中,明显拓宽了频带范围,提高了分辨率。以上结果表明本文设计的控制方法是可行的和有效的。而且在文中也探讨了不同控制参数对实验结果的影响,在实际控制中要根据实验要求以及勘探条件合理设置实验参数。最后对本文进行了总结与展望,并对以后的研究提出了建议。
[Abstract]:In some environmentally sensitive areas, such as urban and complex mountain areas, it is difficult to carry out seismic exploration because of the large volume of vehicle-borne vibroseis and the inconvenient movement under complex terrain. At present, the mineral resources of our country are mostly in the mountainous area, the terrain is complex, the transportation is not convenient. As a kind of vibroseis with small volume, light weight, convenient movement and large output force, impact tamping vibroseis plays a great advantage in geological exploration in the above-mentioned areas. In the research of impact compaction vibroseis, high resolution and high signal-to-noise ratio (SNR) are always the hot issues which need to be solved. In the traditional control mode of shock tamping vibroseis, during continuous impact ramming, the vibration signal is periodic, so there is serious correlation interference in the correlation decoding record, and the sidelobe effect is very serious. Compared with the traditional control method, the improved binary pseudorandom coding method reduces the correlation interference, but the sidelobe effect exists in the autocorrelation function of binary pseudorandom coding, which restricts the improvement of resolution and signal-to-noise ratio of seismic records. In order to solve the problems in the above control methods, this paper presents a control method of shock tamping vibroseis based on the pseudorandom coding of three elements, and designs an excitation signal generator, which is proved to be effective by field experiments. Firstly, the ternary pseudorandom coding technique and the principle of coding sequence generation are studied. By analyzing the autocorrelation of pseudorandom coding, the results show that the autocorrelation function of pseudorandom coding has no sidelobe effect, which is similar to the perfect pulse function. Secondly, the application of ternary pseudorandom coding technology in the control of shock tamping vibroseis is introduced in detail, and the coding matching principle is proposed. Each coding corresponds to different vibration states of impact compaction. According to the principle of coding matching, the excitation signal generator is designed to realize the coding control of shock compaction vibroseis. Aiming at the mechanical characteristics of the shock tamping vibroseis, some signals can not be output correctly. In the control process, feedback control module is added, and the vibration signals on the substrate are collected by the sensor. The correctness of the output signal of shock tamping vibroseis is detected in real time. The pseudorandom coding control of shock tamping vibroseis is realized by the combination of soft and hard, which provides a new direction for the development of shock tamping vibroseis technology. Finally, a practical experiment is carried out. Firstly, by comparing and verifying the consistency of the vibration signal collected and the corresponding vibration signal of the coding sequence, it is determined that the excitation signal generator can send out the control signal correctly; secondly, The correlation seismic records obtained by binary pseudorandom control method and ternary pseudorandom coding control method are compared. The experimental results show that the correlation interference of seismic records obtained by ternary pseudorandom coding control method is obviously reduced. In the autocorrelation results, the ratio of the main lobe to the sidelobe is obviously increased, and the signal-to-noise ratio is improved. In the spectrum analysis, the frequency band range is obviously broadened and the resolution is improved. The above results show that the control method designed in this paper is feasible and effective. The influence of different control parameters on the experimental results is also discussed in this paper. The experimental parameters should be reasonably set according to the requirements of the experiment and the exploration conditions in the actual control. Finally, this paper is summarized and prospected, and suggestions for future research are put forward.
【学位授予单位】：吉林大学
【学位级别】：硕士
【学位授予年份】：2017
【分类号】：P631.4

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