Research On Directional Drilling Technique Of Gas Drainage In Low Gas Permeability Coal Seam

At present, a suit of perfect feasible technological measure of gas drainage in low gas permeability coal seam has never formed in our country. So it has wide application prospect and using value to study gas drainage in low gas permeability coal seam. Directional drilling technique has already become a key link in long broach construction for gas drainage of the mine. The trials and tests on the spot, the experimentations in the laboratory, numerical simulation and calculation, with the theory analyses, are all adopted in this thesis. Through the analyses of many factors which influence broach orbit and press transfiguration owing to the combination of the drilling tools, with the stratum natural oblique strength in the course of drilling, the side cutting models of broach orbit are set up. Then the method that broach orbit predicts fit is put forward. On this basis, directional drilling tools are selected and the craft parameters of drilling are optimized. The scheduled target (single hole length 250m) is realized in long broach construction. The gas drainage rate is up to 25.4% in the span of broach control, and it makes the gas drainage management more concentrative and more scientific.