1. Features of Non-magnetic Drill Collar
Our Non-Magnetic Drill Collars (NMDC) are manufactured from premium, low-carbon austenitic stainless steel. The raw materials undergo a rigorous hot forging and proprietary warm-working process, delivering exceptional mechanical properties and superior resistance to chloride stress corrosion cracking (SCC).
Every drill collar is precisely machined to API Spec 7-1 standard configurations. To maximize fatigue resistance in critical connection areas, all thread roots are strictly cold-rolled, and the internal bores are trepanned to ensure absolute concentricity and precise wall thickness.
2. Typical Oilfield Applications
NMDCs are the fundamental components of any directional BHA. They act as critical housing elements that safely isolate sensitive MWD/LWD surveying instruments from the magnetic interference generated by the conventional steel drill string above.
Beyond isolating interference, the substantial mass of the NMDC provides the necessary Weight on Bit (WOB) required for aggressive penetration rates. Their inherent mechanical stiffness effectively resists buckling under heavy axial loads, ensuring stable wellbore trajectory control in highly deviated and horizontal drilling campaigns.
3. Specification of Non-magnetic Drill Collar
| Connection | O.D. (in) | I.D. (in) | Length (mm) | Bevel Diameter (mm) | Weight (lb/ft) | Bending Strength Ratio |
|---|---|---|---|---|---|---|
| NC23-31 | 3 1/8 | 1 1/4 | 9150 | 76.2 | 22 | 2.57:1 |
| NC26-35 | 3 1/2 | 1 1/2 | 9150 | 82.9 | 27 | 2.42:1 |
| NC31-41 | 4 1/8 | 2 | 9150 | 100.4 | 35 | 2.43:1 |
| NC35-47 | 4 3/4 | 2 | 9150 | 114.7 | 47 | 2.58:1 |
| NC38-50 | 5 | 2 1/4 | 9150 | 121 | 53 | 2.38:1 |
| NC44-60 | 6 | 2 1/4 | 9150 or 9450 | 144.5 | 83 | 2.49:1 |
| NC44-60 | 6 | 2 13/16 | 9150 or 9450 | 144.5 | 75 | 2.84:1 |
| NC44-62 | 6 1/4 | 2 1/4 | 9150 or 9450 | 149.2 | 91 | 2.91:1 |
| NC46-62 | 6 1/4 | 2 13/16 | 9150 or 9450 | 150 | 83 | 2.63:1 |
| NC46-65 | 6 1/2 | 2 1/4 | 9150 or 9450 | 154.8 | 99 | 2.76:1 |
| NC46-65 | 6 1/2 | 2 13/16 | 9150 or 9450 | 154.8 | 91 | 3.05:1 |
| NC46-67 | 6 3/4 | 2 1/4 | 9150 or 9450 | 159.5 | 108 | 3.18:1 |
| NC50-67 | 6 3/4 | 2 13/16 | 9150 or 9450 | 159.5 | 108 | 2.37:1 |
| NC50-70 | 7 | 2 1/4 | 9150 or 9450 | 164.7 | 117 | 2.54:1 |
| NC50-70 | 7 | 2 13/16 | 9150 or 9450 | 164.7 | 110 | 2.73:1 |
| NC50-72 | 7 1/4 | 2 13/16 | 9150 or 9450 | 169.5 | 119 | 3.12:1 |
| NC56-77 | 7 3/4 | 2 13/16 | 9150 or 9450 | 185.3 | 139 | 2.70:1 |
| NC56-80 | 8 | 2 13/16 | 9150 or 9450 | 190.1 | 150 | 3.02:1 |
| 6 5/8 REG | 8 1/4 | 2 13/16 | 9150 or 9450 | 195.7 | 160 | 2.93:1 |
| NC61-90 | 9 | 2 13/16 | 9150 or 9450 | 212.7 | 195 | 3.17:1 |
| 7 5/8 REG | 9 1/2 | 3 | 9150 or 9450 | 223.8 | 216 | 2.81:1 |
| NC70-97 | 9 3/4 | 3 | 9150 or 9450 | 232.6 | 229 | 2.57:1 |
| NC70-100 | 10 | 3 | 9150 or 9450 | 237.3 | 243 | 2.81:1 |
| 8 5/8 REG | 11 | 3 | 9150 or 9450 | 266.7 | 299 | 2.84:1 |