【摘要】 在野外采集阶段,传统的噪音分类方法将噪音划分为相干噪音与随机噪音,前者主要包括源自炮点的面波、折射波、声波等,后者主要指环境噪音.笔者研究认为,相干噪音不仅包括面波、折射波、声波等"原生噪音",也应该包括由震源引发的、由近地表介质不均性导致的"次生噪音",以及环境噪音中具有"相干特征"的部分,比如机械干扰.震源激发后引起地表与大地耦合不良的部分产生对地的重新锤击形成的"次生干扰波"、外界规则干扰波在地震记录上的表现均具有明显的"相干性",并且在近地表结构较为复杂或者外界干扰源众多的情况下,因相互干涉而表现得"杂乱无章",容易让人误以为是"随机干扰",希望用提高覆盖次数等措施进行衰减.事实证明,基于噪音"统计特性"的压噪方法并不能有效衰减次生噪音以及具有相干特征的环境噪音,必须通过检波器"横向大组合",在野外采集阶段加以衰减.随机噪音主要包括系统噪音以及由风吹草动引起的、具有随机特征的环境噪音,同时因为耦合条件不够"理想"而导致的"耦合噪音"也是随机噪音的重要组成部分.文中通过两个"超小"排列试验证明了耦合噪音的存在,同时证明无论环境噪音大小,无论叠加前后,"耦合噪音"均为实际环境噪音强度的5%～20%左右;对埋置好的每个检波器而言,其"相对幅度"是基本稳定的;这说明"耦合噪音"是依附于环境噪音或者地震信号而存在,是一种"伴生噪音",不会独立存在.这种噪音即使在相同地表、相同检波器的情况下,其强度仍然会有差别,这种差别在非"超小排列"的情况下是"不易察觉"的.同时,相干噪音与随机噪音的划分不是绝对的,与我们追求地质目标的尺度有密切关系.更多还原

【Abstract】 According to the typical classification,seismic noises are divided into two types:coherent noise and random noise in the acquisition stage.Coherent noise includes ground roll,refraction wave,acoustic wave etc.Random noises include natural noise and what brought by human being activity.In my opinion,coherent noises not only include the noises mentioned above which come from seismic source directly,but also the scattering noise created by the responding of the inhomogeneous of subsurface to the seismic source’s shock,what could travel in any directions.At the same time,the environmental noises what have coherent characteristics in shot gather,such as noise caused by machine s shaking,should be placed in ’coherent noise’.These two kinds of noises could have similar features with random noise when they are very strong and interfere each other,what could result in a misunderstanding that they are random noises.In practices many attempts to attenuate the above noises based on the statistics characteristics failed,on the contrary the longer-length geophone array in cross-line showed much improvement.Most of ambient noises which have random features come from the shaking of wind,grass,trees etc.On the same time,the ’coupling noise’ caused by the bad coupling condition is another significant source of random noises.The experiment in this paper show the evidence of existence of ’coupling noise’.which equals to about 5 to 20 percents of ambient noise and affects the weak signal coming from the deep layer seriously.The strength of ’coupling noise’ is different even when inserting several geophones of the same type into th same coupling medium,and the subtle difference among various geophones is hard to detected except by using "micro-spread".However,to a specific buried geophone.the Iiroportion of ’coupling noise’ remains roughly stable.Because of the above,the ’coupling noise’ is a secondary noise attached to outside noise and can’t be existing independently.For both coherent and random noises,the main measures to suppress are array receiving and multicoverage technique.The longer length geophone array in cross-line can overcome the scattering noise and environmental noise which has coherent characteristics successfully,and the "coupling noise’ should be paid more attention to than before.Meanwhile the classification of coherent and random noise is not absolute,which largely depends on the size of geological objective what we are pursuing.更多还原