摘要:
频域电磁测深法存在的静态效应问题是由地表浅层电性不均匀体在一次天然电场作用下不均匀体界面积累电荷引起的.积累电荷引起的二次静电场与一次天然电场成线性关系,且二次电场与一次电场的比值K只和地下介质的电性有关,地下介质的电性不变,则K值不变.因此,利用人工源供电的方法,在供电时测量测点一次场和二次场的总场Et;断电后测量二次场E2,然后求取K值,利用各测点的K值和大地电磁法实测电场计算一次电场,进行静态校正.本文采用有限元二维大地电磁正演模拟地下浅层电性不均匀体产生的静态效应,利用K值校正静态效应,获得了成功.结果显示这种方法能有效压制静态效应,达到静态校正的目的.
Abstract:
The static effect of the magnetotelluric sounding method is caused by stored charge on shallow layer electrical inhomogeneity by primary electric field.The induced second electric field caused by the accumulated charge is proportional to the primary electric field, and ratio coefficient K is only related to the electrical property of the underground media.The dielectric properties of the underground media are unchanged, and the K value is unchanged.Therefore, the method of artificial source is used to measure the total field of Et in power supply;the induced electric field E2 is measured in the off instantly, and then the proportion coefficient of K between the two data is calculated.K and measured electric field of the magnetotelluric sounding method are used to correct static effect, the finite element 2D MT forward modeling are employed to calculate the static effect produced by the underground electric uneven body, and K is used to correct static effect, thus achieving success.The results show that this method can effectively suppress the static effect and achieve the goal of static correction.
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