Deflection Laws of Gas Drainage Boreholes in Interbedded Soft and Hard Seams: A Case Study at Xinzheng Coal Mine, China

Table 7

Drilling deviation.

Data classification	Proportion (%)
Vertex angle θ and azimuth angle α are unchanged	0.5
Vertex angle θ changes; azimuth angle α is unchanged	10.9
Vertex angle θ and azimuth angle α both change	81.9
Apex angle θ remains unchanged; azimuth angle α changes	6.7