Study On Fracture Propagation Rule And Technical Measures Of Coal Seam Which Has High Dip Angle

Gas extraction with low input and high efficiency in soft coal seam is still a difficult technical problem to solve in today's world.The main reason is that the permeability of difficult coal seam is very low,which makes gas difficult to escape and poor extraction effect.The firmness coefficient of K9 coal seam in Guizhou Gemudi Zhongjing coal mine is 0.36,and the permeability of coal seam is poor,which is a typical "three soft coal seam".In the regional outburst prevention work of 10903 working face of Zhongjing coal mine,measures such as pre-drainage of coal seam gas by floor gas roadway,bedding drilling,advance drilling and carbon dioxide cracking were adopted,but the final effect was not good,and the regional outburst elimination measures failed,resulting in the situation that the 10903 working face of Zhongjing coal mine could not be excavated and the working face could not be stoped.In order to solve this problem,work in outburst coal mine 10903 face elimination in governance as the backing,to carry out the soft coal seam underground extraction through holes and repetitive pulse strong shock wave seam anti-reflection technology research,summed up a set of mature theory,theoretical system,scientific and feasible technology for coal mine 10903 face gas ortburst eliminatiorf in govenance and security production and create favorable conditions.Paper uses the field investigation and theoretical analysis,laboratory test,field test and numerical analysis methods such as study,finish of soft coal seam underground extraction holes and eade a systematic study of coal seam anti-reflection technology,will be borg and large diameter underground directional drilling,drilling fluid,fiberglass screen completion,downhole pressure extraction,such as repetitive pulse strong shock wave seam anti-reflection technology for a comprehensive and systematic analysis,the various technical link organically unify,form a system,perfect and scientific system of gas control technology,and through the engineering application practice has obtained the following results:(1)it innovatively developed downhole gas extraction technology,successfully solved the common problem of hole formation difficulty in soft coal seam,and realized the hole formation of large diameter and long distance in soft coal seam,hole formation of large Angle(-18°)down-hole drilling and completion of glass fiber reinforced plastic screen tube.(2)through the research on anti-reflection technology of repeated pulse strong shock wave in coal seam,the permeability of coal seam in Zhongjing coal mine was effectively improved,the attenuation coefficient of borehole flow was reduced,the effective influence radius of borehole extraction was expanded to 20 meters,and the effect of gas extraction was significantly improved.(3)through the study and joint application of pore forming technology of soft coal seam and permeability improvement technology of repeated pulse strong shock wave coal seam,a new gas extraction technology based on pore completion of soft coal seam and permeability improvement of coal seam was finally formed,which provided new ideas and methods for gas management in Guizhou region and even in China under similar geological conditions.