利用数值方法研究陆地气枪的震源特性及其影响因素
发布时间：2018-11-06 13:01
【摘要】：监测地下结构以及介质变化是地震学研究的任务之一,选择合适的信号源对监测结果的优劣有着重要的影响。作为区域性地球物理勘探的理想震源,与传统的人工源相比,气枪震源重复性好、低频丰富并且绿色环保,极大地拓展了我们探索地球的手段。陆地水体气枪激发环境与海洋气枪存在显著不同,陆地气枪激发水体为有限小型水体,水体形状各不相同,陆地气枪信号的激发和传播不可避免地受到固液界面的影响。在利用气枪震源进行一些高精度的介质性质监测时,需要详细掌握气枪震源的源部分的特征,以去除气枪震源本身对测量结果的影响。为了研究气枪激发环境对气枪激发信号的影响,探讨气枪震源的能量传播过程,本文结合陆地气枪主动震源在区域尺度地球物理勘探中的应用,辅助以数值模拟方法,进行了不同水体对气枪激发信号性质影响的研究,分析了水体形状对气枪激发信号影响的机制。结合实际的观测数据和数值模拟方法,对快速评估气枪激发后气枪能量的传播过程提出了简单的计算方法。本文结合马刨泉实验,介绍了云南宾川、新疆呼图壁和甘肃张掖气枪地震信号发射台站的工作和取得的进展,发现大容量气枪震源应用到陆地区域尺度地球物理勘测中具有较好的可操作性和很重要的科研意义。利用数值模拟的方法计算地震波的传播,是地震学研究中的有效手段。在主动源探测领域,对地震波在复杂介质中的传播过程进行准确模拟,可以为主动源相关的数据资料的分析解释和区域介质结构反演提供理论支持和依据,有助于利用主动源开展地下介质性质的研究工作。在气枪主动源实验中,由于实地情况非常复杂,如固液界面上发生的反射、折射等现象,水体水位高低的变化、气枪在水体中放置位置的偏移等等因素,都有可能使波场特征发生改变。要想从实际观测的波形中剥离掉这些影响因素,从而得到震源特性,是十分困难的。因此,对气枪震源进行数值模拟的正演研究,有助于我们得到更为准确的震源本身特性。陆地水体气枪激发环境与传统的海洋气枪存在不同。本文通过分析实际气枪激发实验的数据,结合数值模拟实验,从绝对振幅、相对振幅、频率以及形状参数等几个方面,综合分析了水体形状对陆地大容量气枪激发信号的影响。本文的研究表明,不同水体形状对信号存在一定程度的影响,并且不同水体形状对不同频率的信号具有不同程度的影响。在几十米的水体尺度内,陆地有限水体对高频的脉冲信号影响较强,而对低频的气泡脉冲信号影响较弱。陆地气枪信号形成完整的气泡脉冲需要足够的水体体积,而在水体体积足够大的情况下,水体边界越陡,气枪能量转化为低频能量的效率越高,所激发信号波形越尖锐。而这也是陆地有限水体气枪应用的理想水体激发环境。经典气泡振荡理论是解释海洋气枪激发机制的基础理论,它将气枪信号分为压力脉冲信号和气泡脉冲信号两部分来加以阐述。但是在陆地气枪激发中,固液界面的研究一直缺乏准确的理论探讨。虽然无限半空间水体中气枪的激发信号方程可以由经典气泡震荡理论给出,但是由于陆地激发环境边界条件的复杂性,我们很难或者不能求出陆地有限水体中气枪激发信号的解析解。这使得我们有必要寻找一种方法来研究陆地气枪震源的震源特性。依据反投影方法的基本原理,本文改进了算法使之适用于陆上气枪震源的波场监测。通过五组数值模拟实验,本文发现利用布置在水体中的水听器接收到的信号,该方法可以有效地监测到气枪信号的能量传播过程。该方法布置方便,计算迅速,结果可靠,可以有效及时地对气枪震源的效果做出评估,可以为更充分地利用气枪震源提出有益的指导。应用陆地气枪震源可以监测波速变化,但因为气枪数据多来自于单一震源和单侧接收台站的监测配置,我们很难利用传统方法定位波速变化的位置。我们试图通过正演计算对波速变化位置提供一定的约束。首先利用较详细的速度结构信息,建立不同波速异常的试探模型,然后应用数值方法计算不同模型下接收台站的波形信号,与实际数据相比较选出最优模型,估计波速变化的位置以及波速变化的幅度。
[Abstract]:The monitoring of the underground structure and the change of the medium is one of the tasks of the seismological study, and the selection of suitable signal sources has an important influence on the quality of the monitoring results. As the ideal source of regional geophysical exploration, compared with the traditional artificial source, the gas-gun source has good repeatability, rich low-frequency and green and environment-friendly, and greatly expands the means for us to explore the earth. The excitation environment of the air gun of the land water body is different from that of the marine air gun, and the water body of the land air gun is a limited small water body, the shape of the water body is different, and the excitation and the propagation of the land air gun signal are inevitably influenced by the solid-liquid interface. It is necessary to master the characteristics of the source part of the air gun source in order to remove the influence of the air-gun source on the measurement. In order to study the influence of the firing environment of the air gun on the excitation signal of the air gun, the energy transmission process of the air gun source is discussed, and the application of the active seismic source of the land air gun in the regional scale geophysical exploration is discussed, and the numerical simulation method is used. The effect of different water body on the excitation signal of air gun was studied, and the mechanism of the influence of water body shape on the excitation signal of air gun was analyzed. Based on the actual observation data and the numerical simulation method, a simple calculation method is proposed for the propagation of the energy of the air gun after the air gun is excited. In this paper, the work and progress of the seismic signal transmitting station in Binchuan, Xinjiang and Zhangye air gun of Gansu are introduced in this paper. It is found that the high-capacity air-gun source has good operability and important scientific research significance in the land-area-scale geophysical survey. The method of numerical simulation to calculate the propagation of seismic waves is an effective means in the study of seismology. In the field of active source detection, the propagation process of seismic wave in complex medium is simulated accurately, which can provide the theoretical support and basis for the analysis and interpretation of the data of the active source and the inversion of the regional medium structure, and can help to use the active source to carry out the research on the property of the underground medium. In the air gun active source experiment, the characteristics of the wave field can be changed due to the complex field conditions, such as the reflection, refraction and other phenomena occurring on the solid-liquid interface, the change of the water level of the water body, the deviation of the position of the air gun in the water body, and the like. it is very difficult to remove these influencing factors from the actual observed waveform so as to obtain the characteristics of the source. Therefore, the positive performance of the numerical simulation of the air-gun source will help us get the more accurate source characteristics. The air-gun excitation environment of the land water body is different from that of the traditional marine air gun. In this paper, the influence of water body shape on the excitation signal of land mass air gun is analyzed by analyzing the data of the actual air gun excitation experiment, combining the numerical simulation experiment, from the absolute amplitude, the relative amplitude, the frequency and the shape parameter. The research of this paper shows that the shape of different water bodies has a certain degree of influence on the signal, and the different water body shapes have different influences on the signals of different frequencies. In the water scale of several tens of meters, the influence of the terrestrial limited water on the high-frequency pulse signal is strong, and the effect of the low-frequency air-bubble pulse signal is weak. The land air gun signal forms a complete bubble pulse, which requires a sufficient volume of water, and the steeper the water body boundary, the higher the efficiency of the air gun energy conversion to the low-frequency energy when the volume of the water body is large enough, and the more sharp the excitation signal waveform. and is also an ideal water body excitation environment for the application of the land limited water body air gun. The classical bubble oscillation theory is the basic theory for explaining the excitation mechanism of the marine air gun, which divides the air gun signal into two parts of the pressure pulse signal and the bubble pulse signal. However, in the ground air-gun excitation, the research of the solid-liquid interface has been lack of accurate theoretical study. Although the excitation signal equation of the air gun in the infinite semi-space water body can be given by the classical bubble oscillation theory, because of the complexity of the boundary condition of the land-excited environment, it is difficult or impossible to obtain the analytical solution of the excitation signal of the air gun in the land limited water body. This makes it necessary to find a way to study the source characteristics of the land gas gun source. According to the basic principle of anti-projection method, this paper improves the algorithm to be applied to the field monitoring of land-based air-gun source. Through the five-group numerical simulation experiment, this paper finds out the signal received by the hydrophones arranged in the water body, and the method can effectively monitor the energy transmission process of the air gun signal. The method has the advantages that the arrangement is convenient, the calculation is rapid, the result is reliable, the effect of the air gun source can be effectively assessed in time, and the beneficial guidance can be provided for more fully utilizing the air gun source. The application of the land gas gun source can monitor the change of the wave velocity, but because the data of the air gun is much from the monitoring and configuration of the single source and the one-side receiving station, it is difficult to use the traditional method to locate the change of the wave velocity. We try to provide a certain degree of restraint to the position of the wave velocity change through the positive performance calculation. First, using the detailed velocity structure information, a heuristic model of different wave velocity anomalies is established, and then a numerical method is applied to calculate the waveform signals of the receiving stations under different models, and the optimal model is selected according to the actual data, and the position of the wave velocity change and the amplitude of the wave velocity change are estimated.
【作者单位】： 中国地震局地球物理研究所;
【分类号】：P631.4
，
本文编号：2314361
[Abstract]:The monitoring of the underground structure and the change of the medium is one of the tasks of the seismological study, and the selection of suitable signal sources has an important influence on the quality of the monitoring results. As the ideal source of regional geophysical exploration, compared with the traditional artificial source, the gas-gun source has good repeatability, rich low-frequency and green and environment-friendly, and greatly expands the means for us to explore the earth. The excitation environment of the air gun of the land water body is different from that of the marine air gun, and the water body of the land air gun is a limited small water body, the shape of the water body is different, and the excitation and the propagation of the land air gun signal are inevitably influenced by the solid-liquid interface. It is necessary to master the characteristics of the source part of the air gun source in order to remove the influence of the air-gun source on the measurement. In order to study the influence of the firing environment of the air gun on the excitation signal of the air gun, the energy transmission process of the air gun source is discussed, and the application of the active seismic source of the land air gun in the regional scale geophysical exploration is discussed, and the numerical simulation method is used. The effect of different water body on the excitation signal of air gun was studied, and the mechanism of the influence of water body shape on the excitation signal of air gun was analyzed. Based on the actual observation data and the numerical simulation method, a simple calculation method is proposed for the propagation of the energy of the air gun after the air gun is excited. In this paper, the work and progress of the seismic signal transmitting station in Binchuan, Xinjiang and Zhangye air gun of Gansu are introduced in this paper. It is found that the high-capacity air-gun source has good operability and important scientific research significance in the land-area-scale geophysical survey. The method of numerical simulation to calculate the propagation of seismic waves is an effective means in the study of seismology. In the field of active source detection, the propagation process of seismic wave in complex medium is simulated accurately, which can provide the theoretical support and basis for the analysis and interpretation of the data of the active source and the inversion of the regional medium structure, and can help to use the active source to carry out the research on the property of the underground medium. In the air gun active source experiment, the characteristics of the wave field can be changed due to the complex field conditions, such as the reflection, refraction and other phenomena occurring on the solid-liquid interface, the change of the water level of the water body, the deviation of the position of the air gun in the water body, and the like. it is very difficult to remove these influencing factors from the actual observed waveform so as to obtain the characteristics of the source. Therefore, the positive performance of the numerical simulation of the air-gun source will help us get the more accurate source characteristics. The air-gun excitation environment of the land water body is different from that of the traditional marine air gun. In this paper, the influence of water body shape on the excitation signal of land mass air gun is analyzed by analyzing the data of the actual air gun excitation experiment, combining the numerical simulation experiment, from the absolute amplitude, the relative amplitude, the frequency and the shape parameter. The research of this paper shows that the shape of different water bodies has a certain degree of influence on the signal, and the different water body shapes have different influences on the signals of different frequencies. In the water scale of several tens of meters, the influence of the terrestrial limited water on the high-frequency pulse signal is strong, and the effect of the low-frequency air-bubble pulse signal is weak. The land air gun signal forms a complete bubble pulse, which requires a sufficient volume of water, and the steeper the water body boundary, the higher the efficiency of the air gun energy conversion to the low-frequency energy when the volume of the water body is large enough, and the more sharp the excitation signal waveform. and is also an ideal water body excitation environment for the application of the land limited water body air gun. The classical bubble oscillation theory is the basic theory for explaining the excitation mechanism of the marine air gun, which divides the air gun signal into two parts of the pressure pulse signal and the bubble pulse signal. However, in the ground air-gun excitation, the research of the solid-liquid interface has been lack of accurate theoretical study. Although the excitation signal equation of the air gun in the infinite semi-space water body can be given by the classical bubble oscillation theory, because of the complexity of the boundary condition of the land-excited environment, it is difficult or impossible to obtain the analytical solution of the excitation signal of the air gun in the land limited water body. This makes it necessary to find a way to study the source characteristics of the land gas gun source. According to the basic principle of anti-projection method, this paper improves the algorithm to be applied to the field monitoring of land-based air-gun source. Through the five-group numerical simulation experiment, this paper finds out the signal received by the hydrophones arranged in the water body, and the method can effectively monitor the energy transmission process of the air gun signal. The method has the advantages that the arrangement is convenient, the calculation is rapid, the result is reliable, the effect of the air gun source can be effectively assessed in time, and the beneficial guidance can be provided for more fully utilizing the air gun source. The application of the land gas gun source can monitor the change of the wave velocity, but because the data of the air gun is much from the monitoring and configuration of the single source and the one-side receiving station, it is difficult to use the traditional method to locate the change of the wave velocity. We try to provide a certain degree of restraint to the position of the wave velocity change through the positive performance calculation. First, using the detailed velocity structure information, a heuristic model of different wave velocity anomalies is established, and then a numerical method is applied to calculate the waveform signals of the receiving stations under different models, and the optimal model is selected according to the actual data, and the position of the wave velocity change and the amplitude of the wave velocity change are estimated.
【作者单位】： 中国地震局地球物理研究所;
【分类号】：P631.4
，
本文编号：2314361
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