Drill Collars

Drill Collars are one of the parts of a drill’s string. Drill for the Collars is meant to provide weight for drilling purposes. The Drill Collars are thick walled tube like pieces that are machined from solid steel bars, although they are often made from plain carbon steel or the non magnetic alloy of copper and steel or other premium alloys that are non magnetic in nature. Drill collar has bars of solid steel that are drilled from one end to the other to provide a passage for pumping the drilling fluids through the collar.

Collars that are available for drilling have an external diameter that is made of steel and can be slightly machine perfected for making sure of the roundedness. Drill Collars are sometimes perfected with the help of spiral Collars or helical shaped grooves. Drill threaded collar have connections that are male or one end and female on the other and. These are cut into a multiple collar that can be adjusted with screw along with other down hole tools. Drill helps make a bottom hole assembly or BHA.

Types

Spiral Grooving
To avoid differential pressure sticking, the surface of the Drill Collar can be spiral grooved, typically with three right hand spirals.
Drill Collar cross sections shown below show the reduced contact area with the wall of the hole.

SPIRAL GROOVED DRILL COLLAR SPECIFICATIONS
Size O.D.	Depth of Cut	Spirals	Direction	Pitch	Type
41/2 - 51/8	7/32 ± 1/32	3	R.H.	38 ± 1	A
57/8 - 63/8	9/32 ± 1/16	3	R.H.	42 ± 1	A
61/2 - 67/8	5/16 ± 1/16	3	R.H.	46 ± 1	A
7	5/16 ± 1/16	3	R.H.	64 ± 1	A
71/8 - 77/8	11/32 ± 1/16	3	R.H.	64 ± 1	B
8 - 87/8	3/8 ± 1/16	3	R.H.	68 ± 1	B
9 - 97/8	13/32 ± 3/32	3	R.H.	72 ± 1	B
10 - 103/8	7/16 ± 3/32	3	R.H.	76 ± 1	B
11 - 12	15/32 ± 3/32	3	R.H.	80 ± 1	B

Hardbanding
Applied by the metal arc gas shielded consumable electrode process, incorporating granular tungsten carbide, fed automatically into the molten weld pool to obtain uniform distribution.
Precisely controlled pre-heating interpass and post weld heat treatment ensure that only weld overlays of optimum integrity are applied. The deposit is made flush to + 1/32 above the O.D. of the collar.

Stress Relief Features
Downhole tools subject to bending and subsequently cyclic fatigue have been shown to have their connections mechanical characteristics improved by the application of A.P.I. Stress Relief Grooves and Bore Backs. As shown in the illustration below Bore Backs and Stress Relief Grooves are machined in accordance with A.P.I. Specification (Latest Edition).

STRESS RELIEF GROOVE FOR CONNECTIONS
Number or Size and Style ofConnection	Length,Shoulder Face to Groove of Box Member, Tol. +0, -1/8 LX	Diameter of Pin Member at Groove, Tol. +0, -1/32 DRG
NC44	41/8	43/16
NC46 (4 IF)	41/8	421/64
NC50 (41/2 IF)	41/8	43/4
NC56	45/8	519/64
NC61	51/8	555/64
NC70	55/8	647/64
NC77	61/8	727/64
41/2 FH	35/8	415/64
51/2 REG	43/8	455/64
65/8 REG	45/8	527/64
75/8 REG	47/8	613/32

Sizes

Drill Collars are available in lengths of 5, 10, 15,
20, 30, 31 and 32 feet and in nominal sizes ranging from 3½” to 14”.

Common sizes are listed here. Other sizes are available upon request.

DRILL COLLAR SPECIFICATIONS
SIZE O.D INS.	BORE		CONNE	CTION STYLE AND		SIZE	APPROX WEIGHT (30FT LONG) LB.	APPROX WEIGHT (3FT LONG) LB.
	Standard Ins.	Optional Ins.	Standard Bore		Optional Bore
	Standard Ins.	Optional Ins.	A.P.I.	No. Other	A.P.I.	No. Other
3½	1½		NC26	2⅜ IF	NC26	2⅜ IF	1012	1045
4⅛	2	1¾	NC31	2⅞ IF	NC31	2⅞ IF	1045	1078
4¼	2	1¾	NC31	2⅞ IF	NC31	2⅞ IF	1122	1155
4½	2	1¾	NC31	2⅞ IF	NC31	2⅞ IF	1298	1342
4¾	2¼	2¼	NC35		NC38	3½ IF	1412	1463
5	2¼	2	NC38	3½ IF	NC38	3½ IF	1606	1659
5¼	2¼	2	NC38	3½ IF	NC38	3½ IF	1793	1848
5½	2¼	2	NC38	3½ IF	NC38	3½ IF	2046	2112
5¾	2¼	213/16	NC40	4 FH	4½ FH		2253	2328
6	2¼	213/16	NC44		NC40	4½ FH	2486	2570
6¼	2¼	213/16	NC46	4 IF	NC46	4 IF	2728	2816
6½	2¼	213/16	NC46	4 IF	NC50	4½ IF	2761	2851
6¾	2¼	213/16	NC46	4 IF	NC50	4½ IF	3025	3124
7	213/16	2¼	NC50	4½ IF	NC50	4½ IF	3304	3412
7¼	213/16	3	NC50	4½ IF	5½ FH		3586	3705
7½	213/16	2¾	NC50	4½ IF	5½ REG		3885	4013
7¾	213/16	3	NC56	6⅝ REG	NC56	6⅝ REG	4191	4327
8	213/16	3	NC56	6⅝ REG	NC56	6⅝ REG	4514	4653
8¼	213/16	3	6⅝ REG		6⅝ REG		4840	4990
8½	213/16	3	6⅝ REG		6⅝ REG		5181	5337
8¾	213/16	3	6⅝ REG		6⅝ REG		5416	5577
9	3	213/16	NC61	7⅝ REG	NC61	7⅝ REG	5786	5973
9¼	3	213/16	NC61	7⅝ REG	NC61	7⅝ REG	6182	6369
9½	3	213/16	7⅝ REG		7⅝ REG		6538	6750
9¾	3	213/16	NC70	7⅝ REG	NC70	7⅝ REG	6930	7154
10	3	213/16	NC70	8⅝ REG	NC70	8⅝ REG	7260	7480
11	3	213/16	NC77	8⅝ REG	NC77	8⅝ REG	9020	9295
11¼	3	213/16	NC77	8⅝ REG	NC77	8⅝ REG	9460	9768
12	3	213/16	NC77	8⅝ REG	NC77	8⅝ REG	10868	11187
14	3	213/16	NC77	8⅝ REG	NC77	8⅝ REG	14949	15400
With 2 ends 11¼ O.D.