Non Magnetic Drill Collar for Horizontal Drilling: Applications, BHA Placement, and Buyer Specifications

A non magnetic drill collar helps protect magnetic directional measurements from interference generated by nearby steel components in a horizontal drilling bottom hole assembly (BHA). It is commonly selected around measurement-while-drilling (MWD) or other magnetic survey sensors, with its position and length determined by the tool provider’s requirements and the BHA design. For buyers, the key is to specify more than “nonmagnetic”: confirm the required material and magnetic acceptance criteria, dimensions, connections, mechanical properties, and inspection documentation before ordering.

Check now

Who This Guide Is For

This guide is for drilling contractors, directional drilling teams, MWD providers, and procurement professionals sourcing non magnetic drill collars for horizontal or high-angle wells. It explains the product’s role, practical BHA placement considerations, and the information suppliers need to quote a suitable component. Because each BHA and measurement system is different, final dimensions and placement should be confirmed with the drilling and tool-design teams.

How a Non Magnetic Drill Collar Works

Basic concept and core functions

A drill collar is a thick-walled tubular component in the BHA. A nonmagnetic version is made from material selected to limit magnetic influence on nearby sensors; it can also contribute to BHA stiffness and weight, depending on its design and position. It is not a substitute for every steel component in the assembly, and its presence alone cannot guarantee accurate surveys.

Magnetic survey tools determine direction using the Earth’s magnetic field. Nearby ferromagnetic steel or other sources of magnetic disturbance can affect the sensor readings, so the BHA must be designed to provide suitable separation. Nonmagnetic collars are one part of that design, alongside sensor placement, spacing, tool calibration, and the survey method.

Materials and product options

Nonmagnetic collars are commonly produced from nonmagnetic alloy families, including certain austenitic stainless steels and other purpose-selected alloys. The exact grade, heat treatment, and mechanical properties vary by product and application; buyers should not assume that all “nonmagnetic” materials have the same strength, corrosion behavior, or magnetic response. Ask the supplier to identify the proposed material and the basis for its magnetic and mechanical acceptance.

Product options can include different outside and inside diameters, lengths, end connections, and surface or inspection requirements. The connection must match the adjoining BHA components, while the bore must accommodate the intended internal flow path and tool configuration. Any special requirements—such as corrosion exposure, sour-service conditions, or handling constraints—should be reviewed with the engineering team and supplier before material selection.

BHA Placement in Horizontal Drilling

In a horizontal BHA, the nonmagnetic section is generally positioned to provide the required magnetic separation around the directional sensor package. The exact arrangement may place one or more nonmagnetic components near the MWD tool, but there is no universal collar count or spacing rule that fits every assembly. Tool-provider guidance, survey requirements, neighboring component materials, and the planned BHA configuration should determine the final placement.

Placement questions to resolve before ordering

Where are the magnetic sensors located within the MWD or survey assembly?
What separation, collar length, and component arrangement does the tool provider require?
Which neighboring BHA components may influence magnetic measurements?
Do the planned outside diameter, bore, and connections fit the complete assembly?
Are additional nonmagnetic sections needed for the planned survey method or operating conditions?

These questions are especially important in horizontal drilling, where the BHA must meet directional objectives while also fitting the well plan and operating envelope. A collar selected solely by nominal diameter may not provide the required sensor spacing or connection compatibility. Confirm the complete BHA drawing or component list before releasing a purchase order.

Buyer Selection Framework

Specifications to include in an RFQ

A clear request for quotation allows a supplier to assess fit and identify missing information. Include the intended drilling application, BHA position, tool-provider requirements, and required delivery location, then state the product specifications that can be confirmed by the buyer’s engineering team.

Link to Longway

Dimensions: outside diameter, inside diameter, overall length, and any dimensional tolerances.
Connections: connection type, pin or box configuration, thread details, and any relevant mating-component information.
Material and performance: required alloy or approved alternatives, mechanical-property requirements, magnetic acceptance criteria, and service environment.
Quality documents: requested material traceability, inspection records, test methods, and documentation format.
Commercial details: quantity, packaging, destination, required delivery window, and any inspection or export requirements.

For example, a buyer might submit an illustrative configuration of 6.75 in outside diameter, 2.25 in inside diameter, and 31 ft overall length. These figures are only an example of how to state measurable dimensions; they are not a universal horizontal-drilling specification or a recommendation for a particular BHA. Verify every dimension against the tool package, connection design, and project requirements.

Evaluate the supplier’s technical response

Ask the supplier to confirm which requirements can be met and how each will be verified. In particular, request clarification on the proposed material, magnetic test method and acceptance limit, dimensional inspection, and connection inspection. If a requirement is not specified, ask for a written proposal rather than relying on an undefined term such as “standard nonmagnetic.”

Review the scope of supplied documentation before placing the order. Depending on the project, this may include material identification and traceability, dimensional records, inspection reports, and test results tied to the individual product. Do not treat a general product description as proof that a particular collar meets project-specific acceptance criteria.

Pricing, MOQ, and Lead-Time Considerations

Price and delivery depend on the material, dimensions, connections, quantity, inspection scope, and production or sourcing route. Custom dimensions or documentation requirements may affect both quotation and scheduling, while stock availability can vary by supplier and market. Buyers should request a written quotation that separates product scope, inspection or documentation charges, packaging, and shipping assumptions.

Minimum order quantities and lead times are supplier- and specification-dependent, so they should be confirmed for the exact configuration rather than assumed from a catalog listing. To reduce avoidable delays, provide a complete drawing or dimensional schedule, connection details, applicable acceptance criteria, and target delivery date with the initial inquiry. If the BHA design is still under review, identify open items so the supplier can flag dependencies before production or dispatch.

Common Purchasing Mistakes to Avoid

Using “nonmagnetic” as the only acceptance criterion: Define the required magnetic property and how it will be checked.
Ordering by outside diameter alone: Confirm bore, length, connection, and space available in the full BHA.
Assuming one placement works for every tool: Obtain sensor-spacing and placement guidance from the MWD or survey-tool provider.
Leaving documentation until after the order: Agree on test records, traceability, and inspection scope in the RFQ or purchase order.
Comparing quotations with different scopes: Align material, dimensions, testing, packaging, and delivery terms before evaluating price.

Working with Longway

At Longway, we support B2B buyers by reviewing the stated application and purchase requirements for non magnetic drill collars and related steel tubular products. A useful inquiry includes the BHA position, target dimensions, connection details, required material or approved alternatives, magnetic acceptance criteria, documentation needs, quantity, and destination. Where the tool-provider specification is not yet available, we can help identify the information needed to complete the request, while final technical acceptance remains with the buyer’s engineering and drilling teams.

Key Takeaways and Next Steps

A non magnetic drill collar for horizontal drilling is selected to help limit magnetic interference at directional sensors while meeting BHA fit and operating requirements. Its effective placement depends on the sensor location, tool-provider guidance, component spacing, and the complete assembly—not on a universal rule. Material designation, measurable magnetic criteria, dimensions, connections, and quality documentation should all be agreed before purchase.

To move forward, confirm the required collar position and spacing with the MWD provider, prepare a dimensioned specification, and request written confirmation of material, testing, and documentation from the supplier. Send Longway your application, drawing or specification, quantity, and delivery destination to begin a technical and commercial review. This process gives your team a clearer basis for comparing suppliers and selecting a collar that fits the planned BHA.