Drill stems must be designed to transfer drilling torque for combined lengths that often exceed several miles down into the Earth's crust, and also must be able to resist pressure differentials between inside and outside (or vice versa), and have sufficient strength to suspend the total weight of deeper components. For deep wells this requires tempered steel tubes that are expensive, and owners spend considerable efforts to reuse them after finishing a well.
Drill Collar
There are different kinds of drill collars, including slick drill collar, Spiral Drill Collar, non-magnetic drill collar, square drill collar and so on. 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.
● Features
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 .
| 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 | 3 1/8 | 31.8 | 1 1/4 | 9150 | 30ft | 76.2 | 2.57:1 |
| NC26-35(23/8IF) | 88.9 | 3 1/2 | 38.1 | 1 1/2 | 82.9 | 2.42:1 |
| NC31-41(27/8IF) | 104.8 | 4 1/8 | 50.8 | 2 | 100.4 | 2.43:1 |
| NC35-47 | 120.7 | 4 3/4 | 50.8 | 2 | 114.7 | 2.58:1 |
| NC38-50(31/2IF) | 127 | 5 | 57.2 | 2 1/4 | 121 | 2.38:1 |
| NC44-60 | 152.4 | 6 | 57.2 | 2 1/4 | 9150 or 9450 | 30ft or 31ft | 144.5 | 2.49:1 |
| NC44-60 | 152.4 | 6 | 71.4 | 2 13/16 | 144.5 | 2.84:1 |
| NC44-62 | 158.8 | Apr-61 | 57.2 | 2 1/4 | 149.2 | 2.91:1 |
| NC46-62(4IF) | 158.8 | Apr-61 | 71.4 | 2 13/16 | 150 | 2.63:1 |
| NC46-65(4IF) | 165.1 | Feb-61 | 57.2 | 2 1/4 | 154.8 | 2.76:1 |
| NC46-65(4IF) | 165.1 | Feb-61 | 71.4 | 2 13/16 | 154.8 | 3.05:1 |
| NC46-67(4IF) | 171.4 | Apr-63 | 57.2 | 2 1/4 | 159.5 | 3.18:1 |
| NC50-67(41/2IF) | 171.4 | Apr-63 | 71.4 | 2 13/16 | 159.5 | 2.37:1 |
| NC50-70(41/2IF) | 177.8 | 7 | 57.2 | 2 1/4 | 164.7 | 2.54:1 |
| NC50-70(41/2IF) | 177.8 | 7 | 71.4 | 2 13/16 | 164.7 | 2.37:1 |
| NC50-72(41/2IF) | 184.2 | Apr-71 | 71.4 | 2 13/16 | 169.5 | 3.12:1 |
| NC56-77 | 196.8 | Apr-73 | 71.4 | 2 13/16 | 185.3 | 2.70:1 |
| NC56-80 | 203.2 | 8 | 71.4 | 2 13/16 | 190.1 | 3.02:1 |
| 65/8REG | 209.6 | Apr-81 | 71.4 | 2 13/16 | 195.7 | 2.93:1 |
| NC61-90 | 228.6 | 9 | 71.4 | 2 13/16 | 212.7 | 3.17:1 |
| 75/8REG | 241.3 | Feb-91 | 76.2 | 3 | 223.8 | 2.81:1 |
| NC70-97 | 247.6 | Apr-93 | 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 |
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