Matching of Casing Sizes with Bit Sizes
API Bit Standard Sizes
| in (mm) | in (mm) | in (mm) | in (mm) | in (mm) |
|---|---|---|---|---|
| 3 3/4 (95.2) | 5 5/8 (142.9) | 7 7/8 (200.0) | 9 1/2 (241.3) | 17 1/2 (444.5) |
| 4 1/8 (104.8) | 5 7/8 (149.2) | 8 3/8 (212.7) | 9 7/8 (250.8) | 20 (508.0) |
| 4 3/4 (120.6) | 6 (152.4) | 8 1/2 (215.9) | 24 (609.6) | |
| 5 5/8 (142.9) | 6 1/8 (155.6) | 8 5/8 (219.1) | 26 (660.4) | |
| 6 1/8 (155.6) | 6 1/4 (158.7) | 8 3/4 (222.2) |
Domestic Bit Size Series
| in (mm) | in (mm) | in (mm) | in (mm) | in (mm) |
|---|---|---|---|---|
| 3 3/4 (95.2) | 5 7/8 (149.2) | 7 7/8 (200.0) | 9 1/2 (241.3) | 17 1/2 (444.5) |
| 4 1/8 (104.8) | 6 (152.4) | 8 3/8 (212.7) | 9 7/8 (250.8) | 20 (508.0) |
| 4 1/4 (107.9) | 6 1/4 (158.7) | 8 1/2 (215.9) | 24 (609.6) | |
| 4 3/4 (120.6) | 6 1/2 (165.1) | 8 3/4 (222.2) | 26 (660.4) | |
| 5 5/8 (142.9) | 6 3/4 (171.4) | 9 1/2 (241.3) | ||
| 7 1/2 (190.5) | 9 5/8 (244.5) | 10 5/8 (269.9) | ||
| 7 7/8 (200.0) | 9 7/8 (250.8) | 12 1/4 (311.1) | ||
| 14 3/4 (347.6) |
Matching Series of Casing and Bit Sizes
| Casing | Well (Bit Size) | Casing | Well (Bit Size) |
|---|---|---|---|
| 762 (30) | 914.4 (36) | 273.05 (10 3/4) | 219.075 (8 5/8) |
| 508 (20) | 660.4 (26) | 244.475 (9 5/8) | 193.675 (7 5/8) |
| 473.075 (18 5/8) | 609.6 (24) | 200.025 (7 7/8) | 177.8 (7) |
| 406.4 (16) | 469.9~508 (18 1/2~20) | 168.275 (6 5/8) | 139.7 (5 1/2) |
| 339.725 (13 3/8) | 444.5 (17 1/2) | 127 (5) | 114.3 (4 1/2) |
| 298.45 (11 3/4) | 381~444.5 (15~17 1/2) | ||
| 273.05 (10 3/4) | 311.15~381 (12 1/4~15) |
Standard Clearances Between Bits and Casing
| Casing Size | Nominal Inner Diameter Deviation |
|---|---|
| mm | Bit Size |
| OD in (mm) | Wall Thickness mm |
| 5 (127) | 10.72★ |
| 9.19 | |
| 7.52 | |
| 6.43 | |
| 5.59 | |
| 5 1/2 (139.7) | 10.54 |
| 9.17 | |
| 7.72 | |
| 6.98 | |
| 6.20 | |
| 6 5/8 (168.8) | 12.06 |
| 10.59 | |
| 8.94 | |
| 7.32 | |
| 7 (177.8) | 16.25★ |
| 14.98★ | |
| 13.72 | |
| 12.65 | |
| 11.51 | |
| 10.36 | |
| 9.19 | |
| 8.05 | |
| 6.91 | |
| 5.87 | |
| 7 5/8 (193.7) | 12.70 |
| 10.92 | |
| 9.52 | |
| 8.33 | |
| 7.62 | |
| 8 5/8 (219.1) | 14.15 |
| 12.70 | |
| 11.43 | |
| 10.16 | |
| 8.94 | |
| 7.72 | |
| 6.71 | |
| 9 5/8 (244.5) | 19.05★ |
| 15.87★ | |
| 15.11★ | |
| 13.84 | |
| 11.99 | |
| 11.05 | |
| 10.03 | |
| 8.94 | |
| 7.92 | |
| 10 3/4 (273.0) | 15.51 |
| 13.84 | |
| 12.57 | |
| 11.43 | |
| 10.16 | |
| 8.89 | |
| 7.09 | |
| 11 3/4 (298.4) | 12.42 |
| 11.05 | |
| 9.52 | |
| 8.46 | |
| 13 3/8 (339.7) | 13.06 |
| 12.19 | |
| 10.92 | |
| 9.65 | |
| 8.38 | |
| 16 (406.4) | 12.57 |
| 11.57 | |
| 9.52 | |
| 18 5/8 (473.1) | 11.05 |
| 20 (508.0) | 16.13 |
| 12.70 | |
| 11.13 |
Note: ★ Indicates standard size for the respective bit/casing combination. The tables above provide the nominal inner diameters of the casing and the corresponding standard drill bit sizes along with the clearance values between them.
