Application of Surface-To-Roadway TEM for detecting deep aquifer in Coal Field, an example from North China

Transient electromagnetic methods (TEM) are effective tools for the hydrogeological investigations of coal mines. However, the traditional ground-based and underground-based TEMs typically fail to detect the deeply buried water-bearing bodies in the majority of coal mines in northern China, where the quaternary overburden is generally thick and many aquifers exist. In the present study, a surface-to-roadway TEM was proposed which utilized grounded-wire sources to transmit signals with large moments on the surface, and required receivers which had the ability to record signals with high resolution in underground mining roadways. First of all, the proposed device was introduced. Subsequently, a synthetic model was established based on the existing information of Zhuxianzhuang coal field in Anhui Province, China, along with the analysis of forward and inversion results. Finally, the acquisition and processing of field data were conducted. Both the synthetic and field results demonstrated the feasibility and superiority of the proposed method. The deeply buried aquifers were able to be better characterized by the surface-to-roadway configuration than the ground-based surveys.