Numerical simulation study on influencing factors of hole spacing of hydraulic punching based on the effective extraction area

Abstract

In order to determine the reasonable spacing of gas extraction holes under the increase permeability measures of hydraulic punching taking Jiuxin Coal Industry of Jincheng Mining Area as the engineering background, COMSOL Multiphysics numerical software was used to build a Three-Dimensional model of gas extraction holes and simulate the gas extraction process under the increase permeability measures of hydraulic punching with different spacing. The gas pressure evolution law of coal body is analyzed by gas pressure isosurface 3d stereograph, and the influence law of borehole spacing on gas extraction effect is quantitatively studied. The results show that with the increase of extraction time, the effective extraction radius and the influence radius of drilling continue to increase, but the growth rate decreases. At the same extraction time, different coal quantity has a significant effect on the effective influence radius, but has little effect on the extraction influence radius. Under the same extraction time, different coal outrush has a significant effect on the effective influence radius, but a small effect on the extraction influence radius. Extraction time and coal seam thickness are the main restricting factors of hydraulic punching drilling layout. The research results provide a reference for optimizing the spacing of hydraulic punching holes.

Keywords

• Hydraulic punching
• Gas extraction
• Hole spacing
• Effective pumping radius
• Extraction influence radius
• The numerical simulation