Exploration of anomaly separation technology of wide-field electromagnetic method
Tian Hong-Jun, Gu Zhi-Wen, Zhang Guang-Da, Zhao Dong- Dong*, Zhou Hao,Zhang Jian, Guo Bing, and Wang Yu-Chen
1. Sichuan Zhongcheng Coal Field Geophysical Engineering, Research Institute Co.,Ltd.,Chengdu 610072,China.
2. Sichuan Changning Natural Gas Development Co., Ltd., Yibin, Sichuan 610056,China.
3. Nanjing center, China Geological Survey, Nanjing 210016, China.
Abstract：
To improve the accuracy of data processing and interpretation, effective suppression of the regional background field and extraction of the local anomaly field for further analyses represent urgent issues that need to be solved in the wide-field electromagnetic methods. The present study proposes an anomaly separation technique based on the residual method to develop the basic idea of regional field separation in gravity and magnetic exploration. The proposed technique can effectively suppress the regional background field and highlight local anomalies, such as faults and thin layers in inversion imaging, overcoming the shortcomings of traditional interpretation methods. Based on the interpolation-cutting method, a dynamically improved interpolation-cutting operator is proposed to obtain the regional background field by separating it from the local anomaly field. Furthermore, one- and two-dimensional complex geoelectric models are designed to perform calculations, inverse imaging, and anomaly separation. It has been demonstrated that the local anomaly information extracted by the anomaly separation technology describes accurate strata, structures, and faults, obviously superior to the traditional processing results. The proposed method is used to separate the anomalies from the wide-field electromagnetic inversion imaging in the Changning area of the southern Sichuan Province. The local information of the structures, thin layers, and faults obtained by the anomaly separation results is highly consistent with the seismic profile, indicating that the proposed anomaly separation technology is effective and reliable. Further, the proposed technology can effectively improve the inversion imaging accuracy and the interpretation reliability of traditional wide-field electromagnetic methods; thus, it has important application value.
2024, Vol. 21 
