检波器数量对组合压噪能力的影响

根据组合压噪的有关理论,在其他因素不变的情况下,采用数量越多的检波器,组合压制干扰波的效果越好。这使得人们认为在施工中应该采用尽量多的检波器以提高资料的信噪比。但是通过分析组合中检波器数量对规则干扰波,随机干扰波以及耦合高频微震衰减的影响证明:在其他因素不变的情况下,线性等灵敏度组合增加到"γ_max+3"个检波器以后(其中γ_max=组合基距/最小干扰波视波长), 组合对于规则干扰波的衰减能力不再随着检波器数量的增加而显著提高。在组合基距确定的情况下,检波器数量越多,对随机干扰的衰减越明显(包括在组内距小于随机干扰相关半径的情况下);但是增加到一定数量后,衰减效果不再出现明显变化。检波器数量的多少对衰减耦合高频微震没有明显作用。同时指出,确定组合中合理的检波器数量要与组合的摆放形式相结合;组合图形不合理的情况下,增加检波器数量不会显著提高组合的压噪能力;灵敏度分布不合理,是导致组合压噪能力降低的重要原因。在线性等灵敏度组合的基础上,利用玫瑰图进行分析,可以确定工区面积组合(包括道间混波后)中使用的合理的检波器数量。

THE EFFECTS OF THE NUMBER OF GEOPHONES IN ARRAY ON NOISE ATTENUATION

The geophone array in field data acquisition can suppress both the regular interference noise and the scattering interference noise. The regular interference noise is mainly suppressed by directional effect,while the scattering interference noise is mainly suppressed by statistical effect. Relevant theories hold that, when other factors remain fixed, the more geophones are used, the better results are obtained. It seems therefore that more geophones should be used to improve the seismic data quality; nevertheless, the authors' studies have proved that, if the number of geophones in a liner array whose sensitivities are suitably weighted is more than " +3"(where =effective-array-length /minimum-wavelength of regular interference noise), no obvious advantage can be seen by using more geophones. On such a basis, by calculating rose diagrams, the suitable number of geophones in an area-geophone-array or smearing can be pointed out, which is more economical. On the other hand, for the purpose of attenuating environmental noise, the more geophones are used in an array, the better result can be obtained under the condition that the effective array length is fixed. However, when the number of geophones reaches a certain level, no obvious improvement can be made. In addition,the authors' study also shows that the number of geophones has no definite relationship with the couple resonance noise. If the number of geophones in array is to be fixed, the geophone pattern should be taken into account. If the geophone pattern is unsuitable, adding geophones will not be beneficial to the noise attenuation. If the geophone sensitivity is not reasonably distributed, it cannot be helpful to the noise attenuation.