E-E_φ、E-E_x广域视电阻率对比与应用

在准静态极限条件下,利用水平电偶极子电磁场电分量的表达式,讨论了Eφ分量、E x分量的幅值范围。在均匀半空间的条件下水平电场Eφ分量、E x分量幅值范围不同,测量Eφ分量计算广域视电阻率可以扩大野外的观测扇区,减小施工成本。数值计算结果表明广域电磁法也有近区的存在。通过二层地电模型的正演理论曲线的讨论以及野外实测数据的对比与分析,发现E-Eφ分量定义的广域视电阻率受观测角度的影响较E-E x广域视电阻率小,在相应的观测扇区内不会发生视电阻率曲线畸变。

A NEW APPARENT RESISTIVITY OF WIDE FIELD ELECTROMAGNETIC DEFINED BY E-Eφ ＆ E-Ex COMPONENT

Using the electromagnetic fields of a horizontal electric dipole electric component expression, this paper discussed the Ex and Eφ components which have different amplitude ranges, and propose a new apparent resistivity of wide field electromagnetic defined by Eφ component. The authors also studied the characteristics of the apparent resistivity of wide field. Under the condition of the homogene-ous half space, the measurement of Eφ components can expand the field observation sector and reduce the construction cost. Through studying the two-layer model of the forward theoretical curves, the authors have found that the wide field apparent resistivity defined by Eφ component has much smaller observation angle than Ex mode, corresponding to the observed sector where no apparent resistivity curve distortions occur. By calculating apparent resistivity defined by wide field Eφcomponent of type H and type K model, the authors have found that wide field electromagnetic method is more sensitive to low resistance. The numerical results show that the wide field e-lectromagnetic method also has the near-zone.