| Transient electromagnetic method has greater detection depth and high detection resolution, which has important applications in determining the mining structure, calculation of the thickness of salt layer, detecting the aquifer and abnormal structures above open well. In recent years, as mine water inrush, flooding and other water damage accidents occurred frequently, transient electromagnetic method has caused more and more attention in preventing water inrush work of coal. At the moment Downhole Transient Electromagnetic Survey commonly uses the land surface transient electromagnetic technology. It exists problem in many cases, so the simulation of electromagnetic response of the whole space need to be solved urgently.The theoretic formula of electromagnetic fields of Magnetic dipole source in stratified media have been given in several ways at home and abroad. But these methods had bad results in numerical stability. This paper improved the expressions of electromagnetic field on the basis of previous work, and developed a new method of solving the unknown coefficients, ensured the stability of the numerical implementations. Chosed continued fractions to calculat Hankel integration.Meanwhile useed Nabigian's analytic solution of full space and half space to check the results of the paper and had a satisfactory results.In this paper, wo had maded sevral typical model's transient response simulation to guide the work of Downhole Transient Electromagnetic Field and to supply a foundation for TEM data processing and interpretation. Selected four mine exploration's model for simulation. The first two models have equivalent, only a simple analysis of the surface's transient response variation have been given when vary the thickness and the depth of conductive layer. The latter two models are well-well T-R model and well-earth T-R model of mine exploration. We focused the two models here because of theirs typical nature.Chapter IV mainly discussed the transient electromagnetic response of various models when the depth and thickness of the conductive layer varied. In the layered half-space model, the magnetic field has a more sensibility on the varied depths and thicknesses of conductive layer than the electric field, in particular the vertical magnetic field has a strong distinction of the thin conductive layer and deep conductive layer. Main discussed how the thickness and depth of conductive layer in the whole layered space affect the half-space model's result. Electric and horizontal magnetic field have a more sensible response of conductive layer, and in the thickness distinguish between changes in extent, is also higher than the vertical magnetic field. Electric and magnetic field all are more sensitive to the conductive layer depth change. But electric and horizontal magnetic field both have worse sensitivity on the deeper conductive layer than the vertical magnetic field. Therefore, as a half-space measurement, measuring the vertical magnetic field will get more accurate information of depth and thickness to the detective target. but when there exists low-conductivity anomalies under the objective body the whole space measurements should use the vertical magnetic to determine low conductive anomalies's depth, and then make a necessary correction to the electromagnetic results according the situation. Meanwhile, the entire space of the results showed that it will cause an error if view a whole space as a half space to interprete when there exists a conductive layer interference.But in the actual exploration, we often can not predict the formation conditions, at this moment , the whole space response characteristics also can be used to judge whether the half-space can be used to approximation or not.Chapter V focuses on the affect factors of electromagnetic response. Offsets mainly affects the size of the magnetic field's amplitude and the distribution of positive and negative value.The electromagnetic field's amplitude had a big attenuation with distance increases. In the early time amplitudes shocked with offsets increasing, which has a guidance to the actual data processing and interpretation (In the actual application viewed the shocks as IP effect). The electromagnetic devices'arrange mainly affected the the early time's response, but did not affect the late time's results. The early time's amplitude of electric field near the source decay faster with vertical distance increase, and the amplitude decay slower where farther from the source.Horizontal and vertical magnetic field decay more slowly with the increase of vertical distance, primarily affects the symbol change of the amplitude. Electric field variation with time is the early time's results decayed slowly with time and mid-late time's results decayed severely at a closer place to the source. And at a place far away from source electric field is first increased to a peak and then declined. Magnetic field's attenuation over time similar to the field of close points, acco- mpanied by the alternating positive and negative. In Model C, the curve of electric and vertical magnetic field variation is similar, at closer place they all had a worse reflection on the receive's positions's vary, but the horizontal magnetic field had the contrary character, it changed dramatly at the closer distance from the emission source. In addition, because the choice of receiving positions had a similar symmetry about the source, the electromagnetic field of the curve also shows the symmetry. The vertical magnetic field of Model D and vertical magnetic field of Model D changed differently somewhat, model C is less obviously affected by the vertical distance. While the early-mid times'amplitude and positive and negative take-off point of vertical magnetic field of model D are both rich. Also we mainly discussed the limited size coil and it's magnetic dipole equivalent problem. The electromagnetic response of a small coil coincide well with the magnetic dipole at the early and mid times, nearly didn't effect by the offsets, and only had a small degree of separation at late times. The electromagnetic response of large coil and it's equivalent magnetic dipole had greater separation. So when the coil size is not big enough, we can view it as magnetic dipole without the impact of offsets.To sum up, the simulation of the whole space's transient electromagnetic of magnetic dipole is the basic means of studying the electromagnetic response features of layered media. It provided the basis for the inversion of the electromagnetic exploration undergrounded. It had great significance means on guiding the field exploration of Transient Electromagnetic, and supplied a basis for the processing and interpretation of undergrounded transient electro- magnetic method.
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