Network Design Mode of In-Seam Gas Extraction Parameters Using Mathematical Modelling—Take Tangan Colliery as an Example

Table 3

Gas drainage effect of each extraction unit in working face 3307.

Extraction unit	1	2	3	4	5	6
Area length/m	430	301	205	146	103	242
Extraction time/d	350	242	169	119	83	58
/m	6	6	5	4.5	4	2
/m	6	5	4	3.5	2.5	1
Number of fracturing boreholes	49	34	30	24	21	97
Number of extraction boreholes	98	67	60	48	41	195
Average pure volume of fracturing borehole/(m^3/min)	0.02	0.023	0.026	0.034	0.04	0.042
Average pure volume of extraction borehole/(m^3/min)	0.019	0.02	0.022	0.027	0.03	0.03
Total extraction volume/(×10^7m^3)	1.43	0.74	0.51	0.36	0.25	0.83
Gas extraction rate/%	33.50%	26.40%	25.10%	25.00%	25.00%	34.50%