Research on Pressure Measurement Technology of “Coal-rock-coal Arc” Borehole

It is difficult to carry out the pressure test of the rock section in the single coal seam, this paper proposes the use of directional drilling rig to construct of “coal-rock-coal” arc drillings, the pressure test hole will be divided into three sections, sealing by cement is carried out in the first section of the coal hole and the second part of rock hole, sealing length is not less than 50 m. The second section of rock hole and the third section of coal hole are taken as the pressure chambers to form hole sealing of coal-rock mixing section, and ensure the air tightness test of the pressure measuring chamber, so as to reasonably avoid the pressure relief range of coal seam. In Chengzhuang Mine of Jincheng Group, test shows that the gas pressure measured by “coal-rock-coal” arc drilling increased by about 20% compared to the pressure value from coal seam bedding drilling, the measured gas pressure value is closer to the actual gas pressure value.