【作者】 万学娟；

【导师】 孙成禹；

【作者基本信息】 中国石油大学 ， 地球探测与信息技术， 2009， 硕士

【摘要】 面波是地震勘探中广泛存在的一种规则干扰波,它通过形成的高倾角(低速)和强振幅污染地震记录,并且在近地表地震记录中占主导地位。它存在于地震记录中,会大大降低资料的信噪比,在地震记录中,面波的表现形式比较复杂,对于资料的后续处理非常不利。因此,地震记录中面波剔除与压制方法的研究是非常必要的。为寻求更好的压制面波的方法对非理想条件下的面波的性质进行研究势在必行。瑞雷面波是一类低频、低速、能量较强的次生波,且主要沿着介质的分界面传播,其振幅随着与界面距离的增加迅速衰减,几个波长的深度之后位移小到几乎可以忽略。本文从瑞雷波传播的基本理论、波动方程入手,逐步讨论了瑞雷面波在常速度梯度、上覆疏松覆盖层、上覆空气情况、粘弹性介质中的传播特征,瑞雷面波传播速度与泊松比、品质因子、横波速度等地球物理参数的关系,并对其频散方程进行了推导及模型试算。根据粘弹性介质中瑞雷波的传播特征,建立数值算例,并对数值算例进行了去面波试验,验证后续去除面波方法的可行、有效性。在对多种压制面波方法(S-变换压制面波方法、非线性滤波方法、f-k滤波压制面波方法、小波变换压制面波方法)的实现中,总结了各种方法的优缺点。为克服面波压制方法的缺点,使用联合滤波方法对面波进行压制,并提出了f-k滤波的参数选取改进算法-频率-视速度滤波方法。经过实际资料的验证,一维小波变换压制面波经过三次压制可以在不增加运算量的前提下得到最佳的去面波效果。二维小波变换、一维小波变换联合去面波和基于能量分析的参数选取f-k滤波压制面波方法克服了原有的缺点和不足,直接应用于实际资料的处理可行、有效。更多还原

【Abstract】 Surface wave is a regular noise wave existing widely in seismic data. It can be defined as a group of events that contaminates seismic data by forming a high dip (low velocity) and high amplitude cone, which can dominate near-surface events on the seismic records, and it is normally found in land seismic surveys. However, it is the pivotal question in how to remove or pick-up this kind of noise in seismic data. In order to find a better way to suppress surface wave, the characteristics under non-ideal conditions must be researched.Rayleigh wave is sort of sub-wave, which is low-frequency, low-speed, propagates along the surface of the earth, and its amplitude is only significant down to the depth of a few wave lengths. Below that depth, the displacement is negligible. In this paper,the basic theory and wave equation are studied, then the propagation features , overlying air (liquid) , unconsolidated overburden,in the constant gradient velocity and viscoelastic medium, are discussed. Including the relations between Rayleigh wave propagation velocity and the geophysical parameters, such as Poisson’s ratio, quality factors, S-wave velocity. Their dispersion equations are derived and the models are established, depending on the propagation features under viscoelastic medium. The suppression methods are verified effective and viable.After implementing a variety of methods ( such as S-transform、nonlinear filtering、frequency-wave number domain filter、one-dimension and two-dimension wavelet transforms decompose) to suppress surface wave, the advantages and disadvantages of those methods are summed up. Using the united methods to suppress surface waves, to overcome the disadvantages. In addition, a improvement F-K filter method velocity filtering method (frequency- apparent velocity filter) is proposed. Compared with the original methods, the above methods overcome the shortcomings and deficiencies to some extent. After those methods being used to suppress surface of the actual seismic data, the united methods (one-dimension and two-dimension wavelet transforms, f-k filter and two-dimension wavelet transforms) and frequency-apparent velocity filter are verified to be effective. The above methods can be directly used in the practical work. They have special value in seismic data processing.更多还原