检波器组合问题的分析

Analysis on the problems of geophone array

关于检波器组合目前存在着几种不同的观点,归纳主要有:单点接收能否代替组合检波、检波器的点距是否越小越好、组合效应是否随炮检距变化等。针对这些问题,分别进行了讨论和分析。认为:由于数字检波器的问世和高密度采集方法的应用,单点接收采集方式在有些地区获得了较好的效果,但在低信噪比地区检波器组合仍然是提高资料质量的主要手段;通常为了保护有效信号,要求检波器组合具有较小的空间尺度,但从提高资料信噪比角度,检波器的间距并不是越小越好,组合点距和组合图形应根据噪声特点进行设计;排列长度越长检波器点距的时差就越大,可能对组合效果的影响就越大,组合基距应随排列长度变化而变化,但影响组合效果的核心因素是Δt/T(△t为组合点距的时差,T为子波视周期),而Δt/T随排列长度的增加变化很小,实际上对组合效果影响不大。

There exist several viewpoints about geophone array at pres- ent,including that 1) if a single receiver can replace geophone array for seismic acquisition,2) if it is true that the smaller the geophone interval,the better,and 3) if the array effect changes with the off- set,etc.Aiming at the questions,discussions and analyses were carried out.The results show that with the invention of digital geo- phone and application of high density acquisition,the single point receiving acquisition method has aehieved good results in some are- a.But in the area with low S/N,the geophone array is still the main means for improving data quality.In order to protect effeetive signals,the geophone array is expeeted to be with small spatial scale.However,from the point of improving the S/N,the smaller distance of geophones is not much better;the distance between ar- ray points and array figuration should be designed according to the characteristics of noise.Longer spread length has a great moveout of geophone point distanee,which seems to have a great effeet on array effect,array length should change with the spread length, hut the main factor affecting the array is At/T (here At is the moveout of spread point distance and T is the apparent period of wavelet).Because At/T has only a very small change with the in- erease of array length,it has little effect on the array.