陆地地震勘探环境噪声指向性检测与分析

发布时间：2018-04-11 09:38

本文选题：地震勘探系统 + 环境噪声　；参考：《吉林大学》2015年硕士论文

【摘要】：在陆地地震勘探过程中，地震波激发前后会有大量的噪声干扰产生。其中在激发前就存在的环境噪声对实际地震记录有很大影响。它一直存在于整个地震勘探过程，是不可避免的。不同的地震勘探测区，环境噪声的表现形式和强度是不同的。如何有效地压制环境噪声干扰，就成为一个值得研究的课题。一个有效的思路是确定环境噪声的主要表征，根据其特点有针对性地对环境噪声进行处理。当前研究表明，环境噪声存在于整个地震勘探过程中，随环境的不同而改变。环境噪声没有固定的视速度，在时间记录上随机性很强，没有一定的主频率。但环境噪声的来源决定了其还是有规律可循的。环境噪声的主要来源是风源。风成环境噪声在空气中传播，是要满足传播性质的。本文借用海洋环境噪声指向性的概念，使用指向性来描述环境噪声的传播特性。陆地地震勘探环境噪声指向性可以描述环境噪声的传播方向和传播路径，这是指向性的空间特性；它还可以描述环境噪声作用在地震道上的起始时间和影响时间，这是指向性的时间特性。可以知道，陆地环境噪声指向性是一个三维的物理量，分别从空间和时间，描述了环境噪声的传播特性。本文提出了陆地地震勘探环境噪声指向性的概念，并且为二维、三维地震勘探环境噪声指向性建模，给出了一种能检测环境噪声指向性是否存在的方法，并将其应用到模拟记录上，证明了方法的有效性。本文应用该检测方法，对中国安徽的山地实际测区，大庆喇嘛甸林带实际测区和塔克拉玛干沙漠实际测区分别进行了处理。安徽的山地实际测区，，采用二维地震勘探工作方式，待确定的环境噪声传播路径是沿着地震测线的。检测后找到了满足环境噪声指向性特征的实际地震记录，证明了环境噪声在山地测区是存在指向性的。大庆喇嘛甸林带实际测区和塔沙测区，采用三维地震勘探工作方式，环境噪声在三维地震勘探观测平面上，可沿任意路径传播。使用本文给出的检测方法，分别找到了两个地区的环境噪声指向性的分布。其中林带地区由于地形复杂，植被较多，其干扰很严重，因此指向性的表征也不明显。与此相反，沙漠地区环境噪声指向性表现很明显，找到了呈带状分布的环境噪声传播路径。本文通过大量实验，证明环境噪声指向性存在于实际地震勘探中的山地，林带和沙漠测区。实际上环境噪声指向性是广泛存在于各个地区的，只是各个地区的强弱程度不同。指向性描述了环境噪声的传播特性，在今后的去噪工作中，可以依托这一点，配合现有的去噪方法对实际地震记录进行处理，最终提高实际地震记录的质量。
[Abstract]:In the process of land seismic exploration, there will be a large number of noise disturbances before and after seismic wave excitation.The environmental noise which existed before the excitation has great influence on the actual seismic records.It is inevitable that it always exists in the whole seismic exploration process.The expression and intensity of environmental noise are different in different seismic exploration areas.How to suppress the environmental noise effectively becomes a research topic.An effective idea is to determine the main representation of environmental noise and to deal with it according to its characteristics.Current studies show that environmental noise exists in the whole process of seismic exploration and changes with the environment.The ambient noise has no fixed apparent speed and has strong randomness in time record and no main frequency.However, the source of environmental noise determines that it is still regular.The main source of ambient noise is the wind source.Wind-induced ambient noise propagates in the air to satisfy its propagating properties.Based on the concept of directivity of environmental noise, directivity is used to describe the propagation characteristics of environmental noise.The directivity of environmental noise in terrestrial seismic exploration can describe the propagation direction and path of environmental noise, which is the spatial characteristic of directionality, and can also describe the onset time and influence time of environmental noise acting on seismic track.This is the time characteristic of directionality.It can be known that the directivity of terrestrial environmental noise is a three-dimensional physical quantity, which describes the propagation characteristics of environmental noise from space and time, respectively.In this paper, the concept of environmental noise directivity in terrestrial seismic exploration is proposed, and it is modeled as two-dimensional and three-dimensional environmental noise directivity. A method to detect the existence of environmental noise directivity is presented.The method is applied to the simulation record to prove the effectiveness of the method.In this paper, the actual measuring areas in the mountainous area, the Lamadian forest belt in Daqing and the actual survey area in the Taklimakan Desert in Anhui Province, China, are treated by using this method.In the mountainous area of Anhui Province, the work mode of two-dimensional seismic exploration is adopted, and the path of environmental noise propagation to be determined is along the seismic survey line.The actual seismic records satisfying the directional characteristics of environmental noise are found after detection, and it is proved that the environmental noise exists directivity in the mountainous area.In the actual surveying area and the Tasha surveying area of the Lamadian forest belt in Daqing, the environmental noise can propagate along any path in the 3D seismic exploration observation plane by using the three-dimensional seismic exploration mode.Using the detection method presented in this paper, the directivity distribution of environmental noise in two regions is found.Because of the complexity of terrain and vegetation, the disturbance of forest belt is very serious, so the directivity is not obvious.On the contrary, the directivity of environmental noise in desert area is obvious, and the band distribution path of environmental noise propagation is found.Through a large number of experiments, it is proved that the directivity of environmental noise exists in the mountainous, forest and desert survey areas in the actual seismic exploration.In fact, the directivity of environmental noise exists widely in various regions, but the intensity of each region is different.Directivity describes the propagation characteristics of environmental noise, which can be relied on to deal with actual seismic records with existing de-noising methods in the future. Finally, the quality of actual seismic records can be improved.
【学位授予单位】：吉林大学
【学位级别】：硕士
【学位授予年份】：2015
【分类号】：P631.4

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