Description
Spiral non-magnetic drill collars are essential downhole tools that make drilling for oil and gas, geological exploration, and directional drilling operations possible. As part of the Measurement While Drilling (MWD) and Logging While Drilling (LWD) systems, these tools can keep a stable non-magnetic environment and at the same significantly reduce the torque and friction between the drill string and the wellbore.
Our spiral non-magnetic drill collars are made through advanced forging processes, yielding a combination of high mechanical strength and an optimized spiral groove design that enhances drilling performance.
Key Functions of Spiral Non-Magnetic Drill Collars
Spiral non-magnetic drill collars perform multiple functions when used near downhole measurement tools:
- Reducing the contact area between drill string and wellbore
- Lowering get torque and drag in directional and horizontal drilling
- Minimizing the risks of differential sticking
- Providing a non-magnetic stable environment to MWD/LWD tools
- Enhancing drilling performance in challenging formations
By comparison, spiral designs are more efficient than standard non-magnetic drill collars in high-angle and extended-reach wells environments.
Material Options – P550 and P650 Non-Magnetic Steel
We use high-purity austenitic non-magnetic stainless steel materials, primarily including P550 and P650.
P550 (UNS S46910) – Preferred Material
P550 is widely used for high-performance spiral non-magnetic drill collars due to its excellent balance of strength, wear resistance, and magnetic stability.
- Yield strength ≥ 965 MPa
- Low magnetic permeability (μr ≤ 1.005)
- Excellent wear resistance and fatigue performance
- Suitable for deep wells and high-torque drilling
P650 – High Strength Upgrade
P650 is designed for more demanding conditions such as ultra-deep wells and extreme load applications.
Material Characteristics
- Stable magnetic permeability for accurate signal transmission
- High resistance to torsion and cyclic loading
- Good corrosion resistance in high-salinity and H₂S environments
All materials undergo 100% inspection and comply with API and DS-1 standards.
Standard Sizes of Spiral Non-Magnetic Drill Collars
| OD | ID | Length | Spiral Length | Borehole Size |
| 4 3/4″ | 2.25–2.5″ | 9–9.5 m | 3–5 m | 6″–6 1/2″ |
| 6 1/4″ | 2.5–2.8125″ | 9–9.5 m | 3.5–5.5 m | 8 1/2″–8 3/4″ |
| 6 3/4″ | 2.8125–3.0″ | 9–9.5 m | 4–6 m | 8 1/2″–9 7/8″ |
| 7″ | 3.0–3.25″ | 9–9.5 m | 4.5–6.5 m | 9 7/8″–12 1/4″ |
| 8″ | 3.0–3.5″ | 9–9.5 m | 5–7 m | 12 1/4″–17 1/2″ |
| 9 1/2″ | 3.5–4.0″ | 9–9.5 m | 6–7.5 m | 17 1/2″+ |
Custom lengths (6–12 m) and non-standard OD/ID sizes are available upon request.
Thread Types and Connection Options
Our spiral non-magnetic drill collars are available in multiple connection standards:
- NC Series:NC38, NC46, NC50, NC56, NC61, NC70
- REG Series:2 3/8 REG – 7 5/8 REG
- Full Hole (FH) Series:4 1/2 FH – 6 5/8 FH
These connections ensure compatibility with global drilling systems and high interchangeability.
Applications of Spiral NMDC in Oil and Gas Drilling
Spiral non-magnetic drill collars are widely used in:
- Directional and horizontal drilling
- Logging While Drilling (LWD) operations
- Extended-reach wells (ERD)
- Deep and ultra-deep well drilling
- Shale gas and unconventional resources
- Sidetracking and window cutting
- High magnetic formations and complex geological conditions
They are essential for improving drilling efficiency and ensuring accurate downhole measurements.
Manufacturing Process and Quality Control
As a professional forging manufacturer, we maintain strict control over the entire production process.
Integral Forging
One-piece forging ensures continuous grain flow, eliminating internal defects and improving fatigue resistance.
Raw Material Inspection
100% testing including spectrographic analysis, magnetic permeability testing, and mechanical verification.
Heat Treatment
Solution treatment ensures high strength and structural stability.
Precision Machining
- CNC threading for reliable connections
- 5-axis machining for precise spiral grooves
- Surface roughness Ra ≤ 3.2
Non-Destructive Testing
- Ultrasonic testing (UT)
- Magnetic permeability testing (μr ≤ 1.005)
Advantages of Our Spiral Non-Magnetic Drill Collars
- High-strength materials such as P550 for demanding drilling conditions
- Optimized spiral structure for reduced torque and drag
- Excellent wear resistance and long service life
- Strict non-magnetic control throughout production
- Fast delivery and flexible customization capabilities
Why Choose Spiral Non-Magnetic Drill Collars
Compared with standard drill collars, spiral NMDC offer:
- Lower torque and drag in horizontal wells
- Reduced sticking risk in complex formations
- Improved drilling efficiency
- More stable MWD/LWD data acquisition
These advantages make them ideal for modern high-performance drilling operations.
FAQ – Spiral Non-Magnetic Drill Collars
What is a spiral non-magnetic drill collar?
It is a drill collar with spiral grooves designed to reduce friction and provide a non-magnetic environment for MWD/LWD tools.
Why is P550 widely used?
Because it offers high strength, excellent wear resistance, and stable magnetic properties.
What is the advantage of spiral design?
It reduces torque, drag, and sticking risks in horizontal and extended-reach wells.
Can spiral NMDC be customized?
Yes, size, material, and thread connections can be customized.
Contact for Custom Spiral NMDC Solutions
Looking for a reliable spiral non-magnetic drill collar supplier? We provide customized P550 NMDC solutions based on your drilling conditions. Contact us for technical support and fast delivery.
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