Water Content Estimation of Aquifer Using Transient Electromagnetic Method

Mine water is a menace to coal mining. Transient Electromagnetic Method (TEM) is a relatively quick and efficient method to detect the water yield property of a targeted layer. Based on mine-oriented 3D TEM observing system, the signal of induced voltage is obtained. TEM 3D data volume can be calculated through the calculation of late-period resistivity and time-depth conversion. After setting an appropriate apparent resistivity value, we can determine the spatial distribution range of an aquifer. Then, combined with water-filling coefficient of the aquifer, its water content can be finally estimated. The water yield property detection in the No.4 coal seam goaf of 80101 workface in Jude mine of Shanxi, China, demonstrates that the apparent resistivity of this goaf is lower than 3 Ω·m, and the projection area of low-resistivity anomaly zone amounts to 22,383 m. Given by the formula Q=KMS, we can estimate the water volume as 33,574 m. Three boreholes have been constructed for the later dredging and drainage project, which results in a total water yield of 36,774 m, thus the error percentage of the predicted water yield is 8.7%. So it can be concluded that it is feasible to predict aquifer’s water content with TEM method.