Directional drilling technology with mud pulse wireless MWD in underground coal mine

The directional drilling technology with mud pulse wireless MWD in coal mine was presented. We introduce the principle of the technology and analyze three key technologies: the wireless MWD with mud pulse, the compound directional drilling and the compound slag discharge with dual power, and integrate the key supporting equipment including wireless MWD with mud pulse and high strength drill pipe. The test results show that the construction of super-long directional drilling with hole depth of 3 353 m was successfully completed, and the maximum mud pump pressure at the end hole was only 43.8% of the rated pressure. The five directional drilling holes were completed in the complex broken roof, the maximum depth of the hole is 540 m, and the total length is 1 653 m. The mud pulse wireless MWD was used for 551 cumulative measurements, of which 4 were error codes, with a combined bit error rate of 0.72%, and the effective working time is more than 20 days.