提高地震勘探检波器串的抗干扰能力
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摘要
地震检波器串在将含有噪声的合成地震波信号转换成电信号时,不可避免地会受到外界电磁感应干扰,主要包括磁场干扰和电场干扰,这两种干扰均为共模信号。从磁场干扰的等效电路分析可知,减少磁场干扰可以通过增加干扰源与有用信号电路距离和减少有用信号回路面积两种方法实现。从电场干扰的等效电路分析可知,电场干扰可以通过平街设计电路来减小。如今地震勘探中绝大多数使用检波器串联形式,组合基距大。通过采用美国NI公司的PXI工业微型机采集检波器串的信号,进行分析后发现,检波器串不平衡是干扰入侵的主要原因,主要表现为对地电容不平衡,而检波器正负极到采集站输入端线段不等长是对地电容不平衡的直接表现。将检波器负极的连接线增加至与正极连接线长度相等,设计平衡的检波器串,可有效地减少共模信号干扰,提高地震检波器串抗干扰能力,实验也证明了这一点。
Seismic geophone string suffered from outside electromagnetic induction interference inevitably when conversing the noise-bearing synthetic seismic wave signals into electric signals,mainly inclu ding magnetic field interference and electric field interference, both of them are common mode signals. Known from the analysis of equivalent circuit of magnetic field interference, reducing magnetic field interference can be implemented by two approaches: increasing the distance from interferent source to useful signal circuit and reducing the return circuit area of useful signal. Known from a-nalysis of circuit equivalent of electric field interference, the interference of electric field can be reduced by the balancing design of circuit. Currently, geophone string is used in a majority of seismic exploration, in which the geophone distance is large. It is discovered by analysis of signals of geophone string acquired from PXI industrial microcomputer of American NI Company that the unbalance of geophone string is main reason of interference invading, which mainly showed in unbalance of ground capacitance, and unequal length of wire from positive/negative poles of geophone to input terminal of acquisition unit is direct representation of unbalance of ground capacitance. Lengthening the connecting wire of negative pole of geophone until to equal to the length of connecting wire of positive pole and designing the balancing geophone string can effectively reduce the interference of common mode signal, improving the antijamming capacity of seismic geophone string, which is also proved by experiments.
Seismic geophone string suffered from outside electromagnetic induction interference inevitably when conversing the noise-bearing synthetic seismic wave signals into electric signals,mainly inclu ding magnetic field interference and electric field interference, both of them are common mode signals. Known from the analysis of equivalent circuit of magnetic field interference, reducing magnetic field interference can be implemented by two approaches: increasing the distance from interferent source to useful signal circuit and reducing the return circuit area of useful signal. Known from a-nalysis of circuit equivalent of electric field interference, the interference of electric field can be reduced by the balancing design of circuit. Currently, geophone string is used in a majority of seismic exploration, in which the geophone distance is large. It is discovered by analysis of signals of geophone string acquired from PXI industrial microcomputer of American NI Company that the unbalance of geophone string is main reason of interference invading, which mainly showed in unbalance of ground capacitance, and unequal length of wire from positive/negative poles of geophone to input terminal of acquisition unit is direct representation of unbalance of ground capacitance. Lengthening the connecting wire of negative pole of geophone until to equal to the length of connecting wire of positive pole and designing the balancing geophone string can effectively reduce the interference of common mode signal, improving the antijamming capacity of seismic geophone string, which is also proved by experiments.
引文
[1]美国国家仪器公司．Field Wiring and Noise Considerations for Analog Signals．1992,4
[2]孙传友,高光贵．遥测地震仪原理．北京:石油工业出版社,1992,12～14
[3] Burke P J. Luttinger liquid theory as a model of the gigahertz electrical properties of carbon nanotubes. IEEE Transactions on Nanotechnology,2002,129～331
[4]杨乐平,李海涛,赵勇等．LabVIEW高级程序设计．北京:清华大学出版社．2003,305～310
[5]SERCEL公司．SN388 Engineering Update,1999,2
[6]杨乐平,李海涛,杨磊等．LabVIEW程序设计与应用．北京:电子工业出版社,2005,69～77
[7]侯国屏,王坤,叶齐鑫等．LabVIEW7．1编程与虚拟仪器设计．北京:清华大学出版社,2005,178～240
[8]熊翥．复杂地区地震数据处理思路．北京:石油工业出版社,2002,29～31
[2]孙传友,高光贵．遥测地震仪原理．北京:石油工业出版社,1992,12～14
[3] Burke P J. Luttinger liquid theory as a model of the gigahertz electrical properties of carbon nanotubes. IEEE Transactions on Nanotechnology,2002,129～331
[4]杨乐平,李海涛,赵勇等．LabVIEW高级程序设计．北京:清华大学出版社．2003,305～310
[5]SERCEL公司．SN388 Engineering Update,1999,2
[6]杨乐平,李海涛,杨磊等．LabVIEW程序设计与应用．北京:电子工业出版社,2005,69～77
[7]侯国屏,王坤,叶齐鑫等．LabVIEW7．1编程与虚拟仪器设计．北京:清华大学出版社,2005,178～240
[8]熊翥．复杂地区地震数据处理思路．北京:石油工业出版社,2002,29～31
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