There are different kinds of drill collars,including round drill collar,spiral drill collar,non-magnetic drill collar,square drill collar and so on.Ordinary drill collar is the  circular cross section, the center has a water hole,the wall thickness is larger,the nozzle is smaller, the weight of per unit length is greater than the size of drill pipe almost 4- 5 times .The majority of drill collar is thread processing directly on the pipe body , but some of them also use the replaced joint.

(1)Eccentric-weight drill collar is an effective anti-deviation drilling tool,with high drill pressure used in oblique areas,rectifying oblique as well.

(2)When drilling directional wells eccentric-weight drill collar is an effective tool to reduce oblique or straighten the well hole using high drilling pressure.

(3)Eccentric-weight drill collar has the advantages of simple structure,convenient use,connected directly to common drill collar without centralizers,greatly convenient for sinking in,fishing and milling operations.

(4)Eccentric-weight drill collar runs downhole safely,danger of leakage or bit freezing hard to appear.

(5)Pay much attention to avoid mud balling and prevent effect of anti-deviation .

CHEMICAL COMPOSITION

Drill Collar Specification

Thread Type O.D. I.D. Length Diameter of shoulder guide Angle Reference bending strength ratio

mm inch mm inch mm inch

NC23-31 79.4 31/8 31.8 11/4 9150 30ft 76.2 2.57:1

NC26-35(23/8IF) 88.9 31/2 38.1 11/2 82.9 2.42:1

NC31-41(27/8IF) 104.8 41/8 50.8 2 100.4 2.43:1

NC35-47 120.7 43/4 50.8 2 114.7 2.58:1

NC38-50(31/2IF) 127 5 57.2 21/4 121 2.38:1

NC44-60 152.4 6 57.2 21/4 9150or9450 30ftor31ft 144.5 2.49:1

NC44-60 152.4 6 71.4 213/16 144.5 2.84:1

NC44-62 158.8 61/4 57.2 21/4 149.2 2.91:1

NC46-62(4IF) 158.8 61/4 71.4 213/16 150 2.63:1

NC46-65(4IF) 165.1 61/2 57.2 21/4 154.8 2.76:1

NC46-65(4IF) 165.1 61/2 71.4 213/16 154.8 3.05:1

NC46-67(4IF) 171.4 63/4 57.2 21/4 159.5 3.18:1

NC50-67(41/2IF) 171.4 63/4 71.4 213/16 159.5 2.37:1

NC50-70(41/2IF) 177.8 7 57.2 21/4 164.7 2.54:1

NC50-70(41/2IF) 177.8 7 71.4 213/16 164.7 2.37:1

NC50-72(41/2IF) 184.2 71/4 71.4 213/16 169.5 3.12:1

NC56-77 196.8 73/4 71.4 213/16 185.3 2.70:1

NC56-80 203.2 8 71.4 213/16 190.1 3.02:1

65/8REG 209.6 81/4 71.4 213/16 195.7 2.93:1

NC61-90 228.6 9 71.4 213/16 212.7 3.17:1

75/8REG 241.3 91/2 76.2 3 223.8 2.81:1

NC70-97 247.6 93/4 76.2 3 232.6 2.57:1

NC70-100 254 10 76.2 3 237.3 2.81:1

85/8REG 279.4 11 76.2 3 266.7 2.84:1

Note: 1.Drill collar thread type: NC-Digital IF-Internal flat type REG-Normal type

2.Bending strength ratio: the ratio of the modulus of the cross section and the modulus of the cross section of the cross section of the dangerous section of the inner thread

In addition, our company can produce the drill collar and spiral drill collar, which can also produce the special specifications of the drill collar and the high efficiency and wear-resisting lengthening drill collar

O.D. cutting depth Lead  ±25.4

mm in A(mm) B(mm) mm

86 3.375 3.5±0.79 679

98.4 3.875 4.0±0.79 914

101.6～111.1 4～4 1/8 4.8±0.79 914

114.3～130.2 4 1/2～5 1/8 5.6±0.79 965

133.4～146.1 5 1/4～5 3/4 6.4±0.79 1067

149.2～161.9 5 7/8～6 3/8 7.1±1.59 1067

165.1～177.8 6 1/2～7 7.9±1.59 1168

181.0～200.0 7 1/8～7 7/8 8.7±1.59 5.6±0.79 1626

203.2～225.4 8～8 7/8 9.5±1.59 6.4±0.79 1727

228.6～250.8 9～9 7/8 10.3±2.37 7.1±1.59 1829

254.0～276.2 10～10 7/8 11.1±2.37 7.9±1.59 1930

279.4 11 11.9±2.37 8.7±1.59 2032

Advantages of Drill Collar Production Process:

In the process of heat treatment, the drill collar has added a special normalizing process, which makes the thread part grain more refined, enhances the drill collar thread strength, and effectively improves the service life of the drill collar.

Sreel Mark Chemical Composition %

C Si Mn P S Cr Mo Cu Al

4145H 0.42～0.48 0.15～0.35 0.90～1.20 ≤0.03 ≤0.03 0.90～1.20 0.15～0.25 ≤0.2 0.025～0.045

Other Elements：N≤0.015，Ni≤0.5

Drill Collar Mechanical Performance

Drill Collar O