Research On The Rule Of Air Leakage In Sealing Borehole And Gas Extraction

Most of coal mine accidents is gas accident in China,gas extraction must be implement before mining in gas outburst and high gas mine,Coal seam gas extraction are the main means of controlling gas.Sealing is the important step for coal seam gas extraction,reasonable selection of hole-sealing technology and parameters are necessary for efficient gas extraction,it's important to research the way of leakage in hole-sealing.This article trough using the rock mass mechanics theory analysising the stress distribution state around the borehole before it was sealed or not,and explore the main channel of leak in borehole.Then propose "annular leakage broken circle" and establish a leak model of borehole based on it,give the formula for calculating the arilling's flat circle redius?the arilling's sectional area and the borehole's leakage,and analysis the main factors in influence the borehole's leakage.This article also using COMSOL Multiphysics which combined actually coal parameter to analysis the stress distribution state around the borehole when it was sealed or not and if there is active support stress during sealing.At last,do a comparison between Schematic Diagram of Polyurethane Sealing Borehole Technolog," Two Plugging and One Injection " Hole Sealing Technolege and The Hole Sealing Device of Capsular Bag Grouting,using formula to figure out the permeability and sectional area around the borehole.