An experimental study of the correction of the statistical averaging method of frequency points in the first branch of magnetotelluric sounding in the static displacement zone
Qin-Yin LYU1,2,3, Xiao-Bo ZHANG1,2,3(), Gen-Gen QIU1,2,3, Gang WANG1,2,3
1. Institute of Geophysical and Geochemical Exploration, CAGS, Langfang 065000, China 2. National Center for Geological Exploration Technology, Langfang 065000, China 3. Electromagnetic Detection Technology Key Laboratory of Nature Resources, Langfang 065000, China
In practical measurement of magnetotelluric sounding, the static displacement of apparent resistivity is a common phenomenon. Whether it can be identified and corrected efficiently will affect the accuracy of inversion and interpretation directly, especially on condition of regional static displacements. In a magnetotelluric profile with continuous static displacements, the apparent resistivity curves with the same polarization model of adjacent measurement points are less referable to each other, and how to make reasonable static displacement correction is the key to obtaining reliable inversion results. Based on lithologic analysis and experimental tests, a new static displacement correction method for large-point-distance condition is preliminarily summarized in this paper, which is named "the statistical averaging method of frequency points in first branch". In this method, statistical analysis is firstly conducted on the distortion measurement points in the study region, then the first three frequency points of each measurement point (same polarization mode) are averaged, and finally the gained averages of all the distortion measurement points are further averaged to obtain a target value, which is preset to the second frequency point of the first branch of the corresponding apparent resistivity curves with distortion. This method doesn't change the shape, but only changes the position of the first branch of the measuring point curve, so as to reach the preset position. Taking the measured data of magnetotelluric sounding in Zalut area as an experiment, the authors carried out the static correction test, and obtained a good application effect, which also indicates that the method is reasonable and applicable in the magnetotelluric sections with continuous static displacement under the condition of insufficient logging and physical property constraints.
吕琴音, 张小博, 仇根根, 王刚. 大地电磁测深首枝频点统计求平均法在连片静位移区的校正实验研究[J]. 物探与化探, 2020, 44(3): 677-684.
Qin-Yin LYU, Xiao-Bo ZHANG, Gen-Gen QIU, Gang WANG. An experimental study of the correction of the statistical averaging method of frequency points in the first branch of magnetotelluric sounding in the static displacement zone. Geophysical and Geochemical Exploration, 2020, 44(3): 677-684.
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