There are two types of collars:

  • sleek;
  • spiral.

Drill collars are primarily used for creating a drill bit load. To achieve this objective, the entire mass is concentrated in an area close as possible to the bit. Since the main mass is concentrated on these drill string components, a logical conclusion is that it is necessary to choose the maximum drill collar diameter to pull it out of hole where the work is carried out, using overshot. 

DC Typical Sizes
DC Connection Series Outside Diameter A Bore + 1/16-0 B Overall Length (ft) ± 6 inches C DC 31 ft. Weight Approx. (lbs)
NC-26 (2-3/8 I.F.) 3-1/2 1‑1/2 или 1-3/4 30' 803
NC-31 (2-7/8 I.F.) 4-1/8 2 30' 1045
NC-35 4-3/4 2-1/4 31' 1452
NC-38 (3-1/2 I.F.) 4-3/4 или 5 2-1/4 31' 1654
NC-44 6 2-1/4 31' 2567
NC-46 (4 I.F.) 6-1/4 2-13/16 31' 2585
NC-46 (4 I.F.) 6-1/2 2-1/4 31' 3086
NC-46 (4 I.F.) 6-1/2 2-13/16 31' 2849
NC-50 (4-1/2 I.F.) 6-3/4 2-13/16 31' 3124
NC-50 (4-1/2 I.F.) 7 2-13/16 31' 3409
NC-50 (4-1/2 I.F.) 7-1/4 2-13/16 31' 3705
6-5/8 REG. API 7-3/4 2-13/16 31' 4327
6-5/8 REG. API 8 2-13/16 31' 4654
6-5/8 REG. API 8-1/4 2-13/16 31' 4991
7-5/8 REG. API 9-1/2 3 31' 6742
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