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Table 1 Drill bit sizes and drilling methods used in DGE-1
Depth interval | Drill bit size | Drilling method |
|---|---|---|
0–23 m | 40″ (1016 mm) | Auger drilling |
23–165 m | 26″ (660 mm) and 36″ (914 mm) hole opener | Mud rotary drilling |
165–1020 m | 26″ (660 mm) | Mud rotary drilling |
1020–2044 m | 17½″ (445 mm) | Mud rotary drilling |
2044–2119 m | 12¼″ (311 mm) | Mud rotary drilling |
2119–2878 m | 12¼″ (311 mm) | Air rotary drilling |
2878–2972 m | 12¼″ (311 mm) | Percussion drilling using air |
2972–3365 m | 12¼″ (311 mm) | Air rotary drilling |
3198a–3666 m | 8½″ (244 mm) | Mud rotary drilling using lightweight polymer mudb |
3666–3675 m | 8½″ (244 mm) | Percussion drilling using mud |
3675–3701.8 m | 8½″ (244 mm) | Mud rotary drilling using lightweight polymer mudb |