Experimental Study on the Temporal and Spatial Variation Law of Gas Flow in Different Rock Pillar Drainage Boreholes

Zhonghua Wang,M.S Nazir,H.A Aziz

doi:10.1051/e3sconf/202125703026

Abstract

In order to study the temporal and spatial variation of gas flow in different rock pillar extraction boreholes, gas pressure, gas content, gas emission from 100-meter coal holes and coal seam permeability coefficient were measured on site. The site inspected the gas flow in the boreholes at 15m, 7.5m, directly above, 7.5m, and 15m at the lower slab of different rock pillar floor roadways. It analyzed the change law of gas flow in boreholes of 710 floor lanes and 505 floor lanes, which provided a basis for the layout of gas drainage boreholes.

Highlights

It can be seen that the pressure relief effect of the coal seam above the floor roadway, from strong to weak, is directly above the coal seam, lower bank 7.5m, upper bank 7.5m, lower bank 15m, and upper bank 15m
It can be seen that the pressure relief effect of the coal seam directly above the floor roadway is in order of 7.5m and 7.5~15m directly above the coal seam, on both sides
It can be seen that with the increase of the excavation time of the floor rock roadway, the amount of gas emission corresponding to the borehole gradually increases, and the pressure relief effect gradually increases

Summary

Coal seam gas pressure

This time, the pressure measurement and sealing were carried out with a grouting pump for grouting and sealing. When it is estimated that the injected cement slurry is about to reach the position of the screen hole, a technician or senior skilled worker should observe whether there is a backflow phenomenon of clear water at the pressure measurement nozzle. This phenomenon is called slurry return or slurry return. After the drilling is sealed, it should be cleaned in time to prevent the cement slurry from solidifying or depositing in the grouting pump and high-pressure slurry pipe. The air permeability coefficient of the coal seam is measured by the drilling radial flow method. Substitute the relevant formula to calculate the coal seam permeability

Investigation plan for gas flow in drainage boreholes

Conclusion