Analysis Of Anomalous Character And Study Vector Intersection For Downhole Transient Electromagnetic Method

In downhole transient electromagnetic method (TEM), the receiver coil is most likely close to the target, get less from conductive overburden, receive less electromagnetic noise, and so can gain much stronger response than surface TEM. Downhole TEM has been one of the most effective method to explore deep underlying ore deposit with using the borehole, from the foreign research and application. For some reason, the research of downhole TEM is superficial in our country, and not used popularly. These is a great way between abroad and us in data measuring and processing. In this paper, the anomalous character of downhole TEM is analyzed and the data processing method is studied from the basic theory, to promote the application and the development of downhole TEM in our country.The applied primary field expression of optional point in rectangle loop with current I, is deduced form Biot-Savart law, both the primary field computation and the showing of vector distribution map has been realized. It is dear understand the relationship of field source, target and the receive station in the primary field vector distribution map, which has been a useful and indispensable tools to get qualitative interpretation of the downhole TEM data.The process from establish of vortex field to disappear has been studied and the characteristic curves of downhole TEM has been analyzed. Numerical computation is carried out with changing downhole position of downehole TEM longitudinal conductance, size, dip angle, depth of thin plate, size of loop, to analyze the relationship between these parameters and the response. The characters and rules of downhole TEM anomalous curves, is conduced and can help to achieve qualitative and quantitative interpretation.At the base of"equivalent vortex field center", the downhole TEM intersection method is conduced using modern numerical visualization technology. It's universal usability and practicability, is effective and applicable, for the position locate accurately of blind ore body beside the borehole.The"downhole TEM anomalous interpreter program"is completed using MATLAB programming language, which correctness and practicability is proved by applying on model data and field data. The realization of this program can offer a strong technical support for downhole TEM to explore blind ore body beside borehole.