Application of CSAMT method for exploring coal mine in Fujian province, Southeastern China

The coal resource reserve in Fujian province is the third of nine provinces in South China. In several decades, most areas with the distributing of uncovered and semi-covered coal stratum have already been explored. Therefore the exploration work in future should mainly be concealed coal stratum, i.e., under the red-bed, old stratum and volcanic. Because of the thick vegetation, grave hypsography and high deepness prospect target, CSAMT method is used for prospecting on eight prospecting lines in four representative coal stratums. The coal stratum that can be excavated in this section is Lower Permian Series, Tungtzeyan Formation. The thickness of this Formation is more than 680 m. It is the medium coal-contain section in the coal-forming environment, and is the major coal-containing section in Lower Permian Series. The aim of this prospecting is to ascertain the upper and lower depth of the coal stratum, and the prospecting target depth is 1200 m. For this target depth, frequency range between 9600 and 1 Hz is used to get good interpretation, the vertical distance R from transmitter to the survey line is 8 km, the power supply current is 10 A, and voltage is 600 V. Transmitter and receiver time synchronization is controlled by GPS. The difficulties of the CSAMT method in this project are terrain problems and serious static problems. Therefore, in the data processing, major works has been done for terrain correction and static correction, which can smooth inverted results for better interpretation. After comparing the interpretation result of CSAMT data with the investigation result of engineer geology, it is found that there is distinct difference in dielectric properties between coal stratum, upper old stratum, red-bed and volcanic. The result shows that CSAMT method is helpful to identify coal stratum under this geological condition.