# Petrophysics Parameter Inversion and Its Application Based on the Transient Electromagnetic Method
## 5 Conclusions  
1. To enhance the geological interpretability of transient electromagnetic (TEM) inversion results, this study proposes a method for directly inverting rock physical parameters based on [PERSON]'s equation. By incorporating porosity and water saturation into the inversion objective function, the formation of petrophysical parameters can be directly retrieved from the TEM data. To verify the validity and feasibility of the proposed method, a series of geoelectric models with varying porosities and water saturation values were constructed and tested using numerical simulations.
2. The proposed method was applied to surface transient electromagnetic (TEM) surveys at the 8311 working face of the Tongxin Coal Mine. The spatial distribution of water saturation and porosity was determined by integrating subsurface electromagnetic responses with geological data. These results provide a scientific basis for the fine-scale characterization of coal and rock physical properties and for understanding the development patterns of pores and fractures in underground strata.
3. Due to the inherent non-uniqueness of inversion results and the limited applicability of [PERSON]'s equation, errors may be introduced into the inversion of petrophysical parameters. To improve the accuracy of geological interpretation, it is recommended to establish a site-specific petrophysical constitutive relationship for the target exploration area prior to the inversion. This approach reduces the number of unknown parameters and enhances the model constraints, thereby improving the reliability of the inversion results.  
Figure 17: Inversion porosity cross section: (**a**) Line \(1\), (**b**) Line \(2\), (**c**) Line \(3\), (**d**) Line \(4\).  
Figure 18: Inversion water saturation cross-section: (**a**) Line \(1\), (**b**) Line \(2\), (**c**) Line \(3\), (**d**) Line \(4\).  
**Author Contributions:** Writing--original draft, validation, methodology, and formal analysis, X.T.; writing--review and editing, funding acquisition, and conceptualization, X.T., J.Y. and K.L.; review and editing, analysis, and interpretation, D.X., H.Z. and K.W. All authors have read and agreed to the published version of this manuscript.  
**Funding:** This research was funded by the National Key Research and Development Program of China under Grant (Grant No. 2023 YFC3008901), National Natural Science Foundation of China (Grant No. 42230811), and Basic Research Program of Jiangsu (Grant No. BK20241672).  
**Institutional Review Board Statement:** Not applicable.  
**Informed Consent Statement:** Not applicable.  
**Data Availability Statement:** The raw data supporting the conclusions of this article will be made available by the authors upon request.  
**Acknowledgments:** The authors would like to thank the China University of Mining and Technology for providing the facilities required for this research. The authors also appreciate the constructive feedback from the reviewers and colleagues, which helped improve the quality of this paper.  
**Conflicts of Interest:** Author Mr. [PERSON] was employed by the company Shenhua Geological Exploration Co. The remaining authors declare that the research was conducted in the absence of any commercial or financial relationships that could be construed as a potential conflict of interest.