Study On The Compound Perforating Technology To Improve Permeability Of Coal Seam

In various coal mine disasters, gas disaster is the biggest threat to the safety ofcoal mine in our country. At present, the Countermeasures of preventing and cure gasis to carry out gas drainage, which can reduce coal seam methane and gas emission.But the coal seam permeability of most coal mine in our country is poor, the gasextraction rate with simply use of ordinary drilling gas drainage is low and has beenunable to meet the needs of coal mine safety and high efficiency production. How toimprove gas drainage rate becomes the main technical problems today.Compound perforation technique is an efficient well completion technologycombined perforation with fracturing. The subject intends to apply this technology tocoal mine in order to improve the gas drainage rate of low permeability and highgassy coal seam and provide a new technical measure for coal mine gas outburstprevention and control.Firstly, the coal permeability enhancement technology which is prevalent both athome and aboard is analyzed, and the perforating technology equipment and itsauxiliary equipment is also introduced in detail. Using seepage mechanics, blastingmechanics and fracture mechanics as theoretical basis, combined with coal bedmethane occurrence and flow theory to detailedly discuss the flow of gas in the coalseam around the borehole. Using stress wave theory and quasi static pressure theory,compound technique of perforating and anti-reflection mechanism is proposed.Secondly, deeply discussed the scheme design on the perforatingpermeability-increasing technology to drainage gas combined with the actualcondition under the shaft and thoroughly researched the drilling technology,perforator installation method, sealing process, the gap between perforator andborehole wall, hole spacing determination of hole distance, laid theoretical basis andpractical experience for the next step of industrial test.