Reason analysis and solve method to the attenuation of MWD signal in aerated underbalanced drilling

In aerated underbalanced drilling, the attenuation of the mud pluses emitting by the underground measure-while-drilling (MWD) equipment is at a high degree, and monitoring and controlling on well trajectory cannot be measured by ground receptor. By establishing the math-ematical modelling of the MWD signal transmission and analyzing the reasons of restricting the signal transmission, two solutions were proposed and was followed by field test which involve adjusting the installation site of the MWD ground sensor and transforming gas injection manner. The results show that the installation site of the MWD has no influence on the signal receiving, transforming gas injection manner through fully mixing gas and liquid could slightly improve the signal transmission and enhance the effective measurement distance of MWD.