Borehole sealing technology of gas pressure measurement in two stage variable diameter borehole with subhorizontal passed through strata drilling

In order to solve the borehole sealing technical problems occurred in the gas pressure measuring process under the condition of the subhorizontal passe d through strata drilling, based on the conventional borehole sealing technology and the cement self shrinkage effect, a two stage variable diameter pressurized borehol e sealing technology was provided. With the two stage variable diameter of the borehole, a baffle welded at the variable diameter location and a distance to the borehol e outlet reserved for the second sealing, in combination with the high pressure grouting technology applied to the borehole, a technique method to the borehole sealing and pressure measuring was realized. The technology was applied to the seam pressure measurement in No. 1075 gas drainage gateway of Liulong Mine in Baise Grou p. The site test data were high efficiently and accurately measured and obtained. The study results showed that the two stage variable diameter pressurized sealing tec hnology could effectively seal the top sectional notch of the sealing section of the subhorizontal pressure measuring borehole, could have a high leakproofness hole se aling and could provide the guarantee to accurately measure in-situ gas pressure of the seam.