1. Problem raising
Now the coal mine gas extraction generally adopt cement mortar hole sealing process, drilling drilling hole sealing, the period of either the bore is sealed by using dry kelp or cement mortar seal, press the cement mortar using hole sealing pump into the hole sealing section, cement mortar after fermentation at the end of the hole sealing fully, for broached Kong Yan (coal) section is broken (fracture) or section in drilling construction quantity is more, the hole sealing process, there is hole sealing is lax, extraction leakage phenomenon, the occurrence of gas coal and rock mass is not safe extraction, sufficient pressure relief, affect the overall effect of the gas extraction, damage to the mine safety production.
2 problem solving
In order to completely solve the problem of loose drilling and sealing, we improved the cement mortar sealing technology, using the cement mortar pressurized sealing technology, through practice proved that the effect is obvious, to achieve a tight drilling and sealing without leakage.
2.1 site operation methods: immediately after the completion of drilling, the sealing pipe (2~3 inches) with a length of 12 meters below the drilling hole shall be blocked by polyurethane (1 meter) at the top of the sealing pipe, and the sealing section of polyurethane shall be 1 meter. (2) under the drilling holes respectively into a 2 meters long grouting tube (Φ 4 points), a 2 meters long FanJiang tube (Φ 4 points), orifice section 1 meter using polyurethane seal, polyurethane sealing section of 1 m. Connect the grouting pipe with the sealing pump with the catheter. Will seal the hole pump into the cement mortar cement mortar seal hole section. (5) after the slurry pipe appears, timely close the slurry pipe control gate valve, seal hole pump high pressure continue to inject the right amount of cement mortar. Close the grouting tube control gate valve, timely clean the sealing pump and connect the pipe.
2.2 precautions for safe operation: the operator shall not directly face the orifice to prevent the cement mortar from spurting out injuries. (2) the grouting line is firmly connected to prevent falling off and injuring people. (3) when drilling high-pressure grouting, pay close attention to the sealing section of the hole with polyurethane. Stop grouting if slurry leakage occurs. (4) high-pressure grouting should be appropriate, the principle of grouting pressure should not exceed 1.5mpa. The grouting can be stopped and the control gate valve can be closed in time after the cement mortar sealing hole section is filled with high pressure. In order to ensure the sealing section of polyurethane at the top of the sealing tube is firm and in place, polyurethane can be selected for delayed fermentation, or polyurethane blower can be used. The length of the reserching pipe for drilling and sealing holes is adjusted according to the inclination of drilling or the depth of drilling and sealing holes. The cement mortar injected into the right amount of accelerating agent can be added.
3. Effect investigation
3.1 increase in single hole extraction in February, 8 holes were sealed by this process. The negative pressure of extraction from each borehole was more than 20Kpa, and the maximum gas extraction concentration was 94%. After stabilization, the gas extraction concentration was 20%~40%, and the single hole flow reached about 0.2m3/min.
Schematic diagram of single-hole extraction concentration (February)
3.2 pressure drilling to determine accurate: in January I mine in the south a stone adhesive tape machine, shek mun uncovering coal pressure drilling hole sealing construction, adopt the hole sealing technology, drilling hole sealing closely, gas pressure determination, accurate determination of 20 days, observing the gas pressure is increasing day by day, to stabilize the biggest 2.6 Mpa, until completion extraction measure drilling construction, drilling pressure gas pressure unloading attenuation.
4 conclusion
Prevention and cure of coal and gas outburst is an important work of huainan mining group governance gas, gas extraction from work is a top priority, and gas extraction from drilling hole sealing quality, directly related to the gas extraction effect, to ensure the quality of extraction from drilling hole sealing should improve hole sealing process, trying to promote drilling hole sealing process in all kinds of new gas extraction used in drilling and other drilling.
