Response surface analysis of influencing factors of borehole gas extraction effect

Abstract

In order to investigate influence of different factors on borehole gas drainage performance, in-situ stress field test in targeted mining area was carried out. The theoretical model of gas migration in coal matrix fracture system was established, and numerical model was constructed based on field data to simulate change of effective extraction radius under different extraction conditions. Response surface method was used to analyze effect of interaction of different factors on effective extraction radius. Response surface model between each factor and effective extraction radius was obtained. Results show that initial permeability of coal seam has the greatest influence on extraction radius, while the effect of drainage time, drainage negative pressure and borehole diameter decreases in turn. The response surface model has good significance, while the determination coefficient is 0.995 7. Response surface of coal seam initial permeability and extraction time has the largest distortion degree, which indicates that interaction effect of those two parameters on extraction radius is obvious. In contrast, response surface distortion of extraction time and extraction negative pressure is the smallest, indicating that the interaction effect of them is the least significant.

Keywords

• bedding borehole
• gas extraction
• effective extraction radius
• initial permeability of coal seam
• response surface model