The System Of Configuration,Preprocessing And Inversion In TEM

As an electromagnetic method, the Transient Electromagnetic Method (TEM) has several advantages such as outstanding penetrating ability through high resistance layers and high sensitivity to low resistances. Furthermore, TEM is widely used in many fields like resource and engineering exploration because of its easy application, abundant information, high precision, low cost and quick effects.Simultaneously, a few technical problems which need to be solved urgently have emerged, for e.g. data pretreatment (data composite filter, enhanced process for weak information and anomaly separation), rapid inversion technology, landform rectification technology and mapping technology, etc. It is absolutely necessary to solve these problems so that TEM will have a better and broader application.TEM observes the secondary field and weak signals and comparatively high noise level are visible traits, especially with more interference caused by humanities in many engineering geophysical applications. Although multiple stacking of data acquisitions and anti-jamming devices are able to help, it can't be settled completely. Besides, sometimes there are transient responses directly caused by non-eddy current factors in TEM observations, and the "responses" will lead to an extraordinarily complex result, even with appearance of negative responses. All these may encumber normal inverse calculation. Therefore, data of TEM observation must be pretreated. The author hereof use the means of "data composite filter", "enhanced process for weak information" and special "anomaly separation" to solve the problems mentioned above, the effect has been proved by theoretical calculation and practical applications.At present, conventional one-dimensional inversions are mostly iterative inversions, which require users to provide initial model parameters and computational speed is not fast. Two-dimensional and three-dimensional inversions are even slower. In order to promote TEM's applications, it's meaningful to establish a multi-parameter rapid inversion system and offer parameters as apparent resistivities and vertical conductivities of various theoretical models including all fields, terminal formula and smoking ring theory.The terrain factors don't have a major impact on observed data; as a result, TEM is less influenced by terrains in electrical prospecting. However, lack of landform rectification may cause serious consequences in interpretation of anomaly. In the past, most TEM maps were contour maps of apparent resistivity section, which can't reach the precision required by spatial distribution maps of modern areal work; thereby development of horizontal and vertical slicing maps has practical value.The author hereof had a systemic study of all the before-mentioned issues and wrote a relevant and practical TEM data processing system simultaneously. The system which can be used for TEM actual data processing has achieved applicatory successes.