Steel Roller,Carbon Steel Cooling Roller,Vacuum Adsorption Roller,Alloy Steel Conductive Roller Jiangyin Mingda Rubber Roller Co,Ltd , https://www.mingdaroller.comNon-magnetic High-Strength Drill Collar
Non-magnetic drill collars are crafted from low-carbon high-chromium manganese alloy steel, refined through strict chemical composition control and specially forged. These drill collars possess impressive mechanical properties, including high strength and low magnetic permeability, along with excellent resistance to intergranular corrosion cracking and abrasion. They play a crucial role in directional drilling operations when used alongside Measurement While Drilling (MWD) and Logging While Drilling (LWD) tools. This allows for accurate magnetic measurement of well trajectories using instruments placed within the drill string. A magnetic measuring device (MWD) functions within the non-magnetic drill collar and can measure the Earth's magnetic field without being affected by magnetic interference. The measuring instruments are isolated from magnetic interference caused by the Bottom Hole Assembly (BHA) and steel components in the drill pipe.
Chemical Composition
Below is the chemical composition of different grades of non-magnetic drill collars:
| Grade | Chemical Composition and Its Content (%) |
|-------|------------------------------------------|
| | C | Si | Cr | Mn | Ni | Mo | N |
| W-1 | ≤0.08 | ≤0.8 | 13.5-16.5 | 16.0-18.5 | 1.0-3.0 | 0.40-0.85 | 0.25-0.40 |
| W-2 | ≤0.03 | ≤0.8 | 13-16 | 18.5-22.0 | 1.0-3.0 | 0.40-0.80 | 0.30-0.45 |
| W-3 | ≤0.03 | ≤0.8 | 16.5-18.5 | 18.5-22.0 | 1.0-3.0 | 0.40-0.80 | 0.50-0.80 |
Mechanical Properties
The mechanical properties of these drill collars vary depending on the grade and outer diameter range:
| Grade | Outer Diameter Range (mm) | Yield Strength (MPa) | Tensile Strength (MPa) | Elongation (%) | Charpy Impact Work (J) | Hardness (HB) |
|-------|---------------------------|----------------------|------------------------|----------------|------------------------|---------------|
| W-1 | 79.4-174.6 | ≥758 | ≥827 | ≥20 | ≥85 @ 21°C, ≥40 @ -25°C | 285-400 |
| | 177.8-279.4 | ≥689 | ≥758 | | | |
| W-2 | 79.4-174.6 | ≥827 | ≥896 | ≥25 | ≥150 @ 21°C, ≥40 @ -25°C | 285-365 |
| | 177.8-279.4 | ≥758 | ≥827 | | | |
| W-3 | 79.4-174.6 | ≥965 | ≥1034 | ≥20 | ≥100 @ 21°C, ≥40 @ -25°C | 300-400 |
| | 177.8-279.4 | ≥965 | ≥1034 | | | |
These non-magnetic drill collars are designed to withstand harsh drilling conditions while ensuring precise magnetic measurements, making them essential for modern directional drilling operations. Their unique combination of strength and non-magnetic properties ensures reliability and accuracy in challenging environments.