Application Of Csamt Static Effect Of The Identification And Correction

Controlled-source Audio-frequency Magnetotelluric(CSAMT)are developing from the Magnetotelluric(MT),which is used to correct Signal randomness and weakly.The CSAMT is a kind of geophysical methods that are using artificial field to detect the different resistivities on different depths by changing the transmitting and receiving frequencies,this geophysical method has Anti-interference capability,high resolution and great depth exploration.In recentyears,CSAMT is successfully used in the area of mining,terrestrial heat,groundwater,oil and gas and so on.Because of using artificial field,Also it will have a range of issues,such as:near-sourcefield effect,source-overprint,shadow effect and so on.Static shift is one of the difficult problems that have to be solved in CSAMT.The generation mechanism and characteristics of the static shift are discussed in this paper.The galvanic distortion due to small-scale surface and shallow electric in homogeneities often leads to distortion of observed and inverted resistivity data.The appearant resistivity curve in the loglog coordinate system has parallel static shift effect while the phase curve has no effect.To distinguish between abnormal data and static shift effect,we advance using the correction coefficient or wavelet analysis.And appoint correction coefficient r_xy＞0.85 or wavelet analysisα＜0 to distinguish static shift effect.At same time by referencing literature of home and abroad,we have discussing many effective methods,such as the curve-shitting method,spatial filtering method,wavelet -analysising method,the method using the phase data analysis or using magnetic data analysis,cooperative inversion,and two-dimensional inversion.As the representative of spatial filtering method,The EMAP filtering method is very important part in this paper,it belongs to low-pass filtering with a Hangning window,we have two methods to analysis,one is a fixed-length window filter,The Filtering effect have changed with a number of input,more numbers,more perfection,but the Horizontal details will be destroyed.The Other is an daptive-moving -average filter,we can change filter window with skin depth on the reference frequency.The idea of two methods is different,but the essence is same.Which is to change the numbers of points in the window.The abnormity has been impaired.So we can gain The EMAP filtering method has flexible and delicate.At last we integrate theory-model and example to explain how to choose the reference frequency and apply.