Underground foam drilling tests in soft seam

The development and utilization of soft coal seam is increasingly important as the coal resources become scarcer, however, the existing drilling technology is relatively backward. To meet the needs of drilling in soft coal, a new technology, which is drilling with foam in soft coal seam in Huaibei Zouzhuang mine, is discussed in this paper. In the field tests, the foam in 1^# well could not form a circle. The well wall collapsed in 2^# well and typical phenomenon of returning slag was observed in 4^# well. This paper makes a detailed analysis for specific accidents, and carries out reasonable solutions. 3 wells of depth greater than 200m were finished in the field tests, which not only effectively increased the drilling depth in soft seam and the success rate of drilling projects, but also decreased the dust pollution in the field.