Abstract:
Under the condition of a certain effective extraction radius, in order to eliminate extraction blind blank zone formed in coal seam gas borehole drainage, borehole layout can be adjusted, the main measures include "delta mode" borehole layout and shortening borehole distance layout. In order to eliminate drainage blind spots, the number of borehole needs to be laid roughly equal to the original; the numbers of boreholes needs to be laid are about 2 times than the original, which causes some coal area repeated drainage, and wastes a lot of resources. In order to reduce the number of construction borehole, this paper presents a new borehole layout method that lay outing along the coal seam borehole distance of 3
1/2R(
R represents the effective drainage radius), lay outing inclination the coal seam borehole distance of 1.5
R or lay outing inclination the coal seam borehole distance of 3
1/2R, lay outing along the coal seam borehole distance of 1.5
R. The number of boreholes needs to be laid at this time is only about 1.54 times than the original. Such layout method can eliminate blank zone formed in coal drainage gas, but also reduce the number of construction borehole, and save a lot of resources and improve the efficiency of borehole drainage.