Research Article
Speculum Observation and Trajectory Measurement in Gas Extraction Drilling: A Case Study of Changling Coal Mine
Table 3
Gas drainage borehole trajectory measurement results (average value).
| | Borehole type | Deviation of borehole inclination (°) | Azimuth deviation of borehole (°) | Vertical height deviation (m) |
| | This coal seam drilling | -2.4 | +1.8 | -3.3 | | High-level drilling | -4.2 | +2.2 | -5.8 | | Upper adjacent layer drilling | -0.6 | -0.6 | -0.8 | | Lower adjacent layer drilling | +1.8 | +1.3 | +2.5 |
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