摘要
大地电磁测深实际测量中,视电阻率的静位移是常见现象,有时会遇到连片静位移的区域,能否对其正确识别与校正将直接影响到反演解释结果的准确度。针对出现连续静位移区的大地电磁测深剖面,相邻测点间同极化模式的视电阻率曲线可参考性较低。本文基于岩性分析,通过实验,初步总结出一套针对连片区的静态位移校正方法——首枝频点统计求平均法。本方法先对研究区浅地表同一地层分布区的畸变测点进行统计,再统计每个测点(相同极化模式)前三个频点的平均值,将这些畸变点的平均值再进一步做平均,得到的值将会作为相应畸变点视电阻率曲线首枝(第二个频点)的预置位置。该方法不改变测点的曲线形态,只改变测点曲线首枝位置,使其达到统计出的预置位置。将该方法应用在扎鲁特地区大地电磁测深实测资料的静校正实验中,取得了较好的应用效果。这也说明,大地电磁测深的剖面连片静位移区资料处理,在没有大量的测井和物性约束条件下,使用首枝频点统计求平均法具有一定的合理性和参考性。
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.
作者
吕琴音
张小博
仇根根
王刚
LYU Qin-Yin;ZHANG Xiao-Bo;QIU Gen-Gen;WANG Gang(Institute of Geophysical and Geochemical Exploration,CAGS,Langfang 065000,China;National Center for Geological Exploration Technology,Langfang 065000,China;Electromagnetic Detection Technology Key Laboratory of Nature Resources,Langfang 065000,China)
出处
《物探与化探》
CAS
北大核心
2020年第3期677-684,共8页
Geophysical and Geochemical Exploration
基金
公益性基础地质调查二级项目(DD20190030)
基本科研业务费专项资金项目(AS2017Y05、ASJ2016J12、JYYWF20180912)。
关键词
大地电磁测深
静态位移
静校正
反演
magnetotelluric sounding
static displacement
static correction
inversion
