检波器尾锥结构对地震采集信号的影响
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摘要
本文从降低地震勘探中表层低速带对高频信号的吸收衰减、增强检波器与地表的耦合入手，对检波器尾锥结构进行改进，即增加检波器尾锥长度，从而提高检波器接收有效信号的能力，有利于高频信号的采集和保真。本文首次对长尾锥检波器的实际接收机制进行分析，并从理论上进行推导，指出增加检波器尾锥长度可引起叠加效应。通过对检波器尾锥频率特性曲线的理论推导，认为叠加效应对高频信号的压制程度与尾锥长度、表层传播速度和尾锥材料的传播速度有关，而且叠加效应对拓展检波器的有效接收频带、保护高频信号是极其不利的。通过试验表明，要想获得宽频带的地震信息，检波器尾锥也不能做得太长，应根据不同的表层条件，选择合理的尾锥长度。
Seismic geophone tailcone is improved so as to enhance the coupling between geophone and ground and then to reduce the absorption attenuation of high frequency signal in surface low-velocity layer. To speak exactly, the geophone taiIcone is lengthened to ameliorate geophone's detection of effective waves and to favour acquisition and fidelity of high frequency signals.Detection mechanism of long tailcone geophone is analysed minutely in theory.This analysis says that tailcone lengthening results in stacking effect. The theoretical derivation of frequency curve of geophone tailcone came to the conclusions that suppression degree which stacking effect exerts on high frequency signals has something to do with tailcone length and velocities in surface layer and tailcone material,and that stacking effect is very unfavourable to both widening an useful receiving frequency band of geophone and protecting high frequency signals.It is shown experimentally that to collect the seismic signals of wide frequency band needs resonable tailcone length, which must be chosen according to surface layer condition.
Seismic geophone tailcone is improved so as to enhance the coupling between geophone and ground and then to reduce the absorption attenuation of high frequency signal in surface low-velocity layer. To speak exactly, the geophone taiIcone is lengthened to ameliorate geophone's detection of effective waves and to favour acquisition and fidelity of high frequency signals.Detection mechanism of long tailcone geophone is analysed minutely in theory.This analysis says that tailcone lengthening results in stacking effect. The theoretical derivation of frequency curve of geophone tailcone came to the conclusions that suppression degree which stacking effect exerts on high frequency signals has something to do with tailcone length and velocities in surface layer and tailcone material,and that stacking effect is very unfavourable to both widening an useful receiving frequency band of geophone and protecting high frequency signals.It is shown experimentally that to collect the seismic signals of wide frequency band needs resonable tailcone length, which must be chosen according to surface layer condition.
引文
1 陆基孟.地震勘探原理,石油工业出版社,1982
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