The Electromagnetic Field Distribution Generated From The Orthogonal Horizontal Magnetic Dipole Source

Electromagnetic method based on the plane wave Cagnird apparent resistivity has been used widely. It is an research direction and trend to realize from scalar measurement to tensor measurement by a single source to multi-source and from natural source to artificial source. Tensor measurement realized with multi-source is more suitable for complex,two dimension structure and more actual geological conditions, and can also realize measurement in any azimuth.The orthogonal horizontal magnetic dipole source simulates the natural electromagnetic field effectively, and conveniently realizes the tensor survey of controlled source electromagnetic in a high frequency band. The field distribution of orthogonal horizontal magnetic dipole source is the theoretical foundations to determine the field operation method.This thesis infers the electromagnetic field components expression of horizontal magnetic dipole source on the homogeneous model and one-dimensional horizontal layer model, and calculates the electromagnetic field components of the orthogonal horizontal magnetic dipole source using the principle of superposition. It obtains the tensor apparent resistivity through the computation tensor impedance; It analyzes the electromagnetic field components of the single horizontal magnetic dipole source and the orthogonal horizontal magnetic dipole source, the scalar apparent resistivity, the tensor apparent resistivity and the phase distributed rule; It studies the influence of the separation, the source angle, the earth-resistivity to the tensor apparent resistivity; It analyzes tensor apparent resistivity curve of the typical horizontal layered model. It confirms the theoretical analysis result through the field experiment and the mineral exploration.The research indicates that:The horizontal components of the electromagnetic field show relatively low value belt in each quadrant, the scalar apparent resistivity show a distortion belt in the same position, while the tensor apparent resistivity doesn't show distortion belt; The tensor apparent resistivity is low in the near zone, and high in the transition region, and tending to the true value in the far zone. According to separation and the earth-resistivity reasonably definited the distance of far zone, as far as possible avoids surveying in the near zone and the transition region; When one-dimensional horizontal layer model, the bottom high-resistance layer and the high-resistance of transition region is unable to distinguish, then the bottom low-resistance layer and the high-resistance of transition region may distinguish. And the field experiment carried out indicates that:In the far zone, the source angle has no effects on the measurement result, namely measurement can be done in any azimuth in the far zone. Through the testing profile and the mineral exploration prove the advantage of the orthogonal horizontal magnetic dipole source. Finally it summarizes the methods and techniques of the electromagnetic sounding method using the orthogonal horizontal magnetic dipole source.