Theoretical Channel Model and Characteristics Analysis of EM-MWD in the Underground Coal Mine

The measurement while drilling (MWD) system in underground coal mine currently uses wire for signal transmission. However, it has shortcomings such as strict technical requirements cable drill pipe processing and high cost of use. Electromagnetic (EM-MWD) is a new technology rate information transmission with fast speed low not affected by the media. Hence, necessary to investigate reliable electromagnetic channel which suitable mine. This study selects excitation method through comparison conducts theoretical research on this basis. Based classical theory, equivalent line adopted calculate analyze characteristics, electrical properties seam surrounding rock are considered. results demonstrate that formation resistivity, emission frequency main factors affecting On basis uniform model, model established combining segmented theory. layered can be better used evaluate regional applicability EM-MWD system.