Study on Gas Pressure Measuring Technology with Downward Borehole Drilling Through Aquifer

According to the soft surrounding rock, easy broken, easy falling, hard to successfully measure the real seam gas pressure, when the downward pressur e measuring borehole in No.8-1 seam of Zhaozhuang Mine passed through two limestone aquifers, with the analysis on the suitable conditions of each borehole sealing method for the borehole through the aquifers, in combination with the actual geological conditions of Zhaozhuang Mine, two pressure measuring boreholes were set at t he same pressure measuring place.No.1 borehole was tested with the full borehole grouting-secondary borehole cleaning-grouting borehole sealing method for borehol e sealing and pressure measurement.The results were not successful to seal the borehole and the water pressure measured was 0.98 MPa.The borehole sealed and pr essure measuring of No.2 borehole was conducted with the double casing pipe and pressurized grouting borehole sealing method.After the test, the method could well t 0 seal the cracks of the aquifer, support and reinforce the soft surrounding rocks and the in-situ gas pressure value of No.8-1 seam accurately measured was 0.40 MPa.