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Downhole Drilling Tools
Downhole Drilling Tools for Oil & Gas Projects
China Welong coordinates supplier development, purchasing supervision and quality-control support for the nine downhole tool families against the RFQ, drill-string context and defined inspection requirements. The quotation identifies the responsible manufacturer, proposed route and inspection scope.
9 Product Routes
API Scope Checks
BHA Context Gate
Lifecycle Status
Inspection Inputs
International Coordination
Select Downhole Drilling Tools by Function and Evidence Needed
Catalog fit can hide a system-context mismatch. Use the first open gate below to decide whether the next action belongs to drilling engineering, operations, procurement or QA.
Q — The Honest Routing Test
A catalog selection is not always ready for quotation when the complete string or evidence owner is unknown. China Welong sources and inspects against the approved RFQ, while the engineering team owns the trade-off between placement, operating window and failure risk.
! — Selection Notice
Catalog dimensions and connections are necessary inputs, but they do not approve a tool for a complete drill string. Review placement, string dynamics, RPM, WOB, torque, flow, pressure, temperature, well geometry, formation and prior failure history with the responsible operator and engineering team.
Describe the job
- vertical, directional drilling or horizontal well
- Rig, wellbore conditions and formation properties
- Drill bit interface, hydraulic window and real-time data
- Target drilling performance and operational limits
Separate other tool families
- completion tools, intervention tools and workover equipment
- casing, tubing, coiled tubing and wireline
- Packer, bridge plugs, perforating guns and stimulation tools
- Fishing tools, logging tools, downhole sensors and mills
Keep outcomes conditional
- Optimization and deployment remain engineering decisions
- Durability, tool life, downtime and productivity need condition-specific evidence
- Precision fit does not prove increased safety or field-proven performance
- Corrosive service and pressure limits need product-specific review
9×3 Tool-to-Evidence Matrix
| Tool route | Function layer | Specify first | Verify for the quoted product |
|---|---|---|---|
| Drilling Jars | Deliver an impact when the string is stuck | Impact direction, pull/load window, circulation and placement | Model data, connection, test scope and release records |
| Heavy Weight Drill Pipe | Bridge stiffness and weight between collar and drill pipe sections | Size, connection, length, construction and string position | Material trace, dimensional results and applicable scope |
| Drill Collar | Add weight and stiffness near the lower assembly | OD, bore, length, connection, material and profile | Material identity, heat treatment, dimensions and marking |
| Non-Magnetic Drill Collar | Support measurement-sensitive sections | Magnetic requirement, material, dimensions and connection | Material certificate, magnetic test method and result |
| Drill Pipe | Transmit rotation, load and drilling fluid | Size, grade, tool joint, coating, hardbanding and length | Applicable API 5DP scope, traceability and inspection basis |
| Drilling Mud Motor | Convert hydraulic energy into bit rotation | OD, lobe/stage, flow, RPM, torque, fluid and temperature | Model curve, bend setting, test condition and service limits |
| Roller Reamer | Ream and condition the hole while reducing contact concentration | Hole size, formation, cutter form, connection and placement | Cutter build, dimensions, hardfacing and inspection results |
| Hole Opener | Enlarge a pilot hole to a target diameter | Pilot size, opened size, formation, cone layout and connection | Drawing, cutter details, weld/assembly checks and final dimensions |
| Drilling Stabilizer | Control contact and support assembly behavior | Hole size, blade/sleeve form, position, material and hardfacing | OD, blade condition, material trace and placement review |
“9×3” means nine product routes across function, specification input and verification evidence. It is an RFQ framework, not an industry standard or BHA engineering approval.
DOC.REF // DRILLING_PORTFOLIO
Explore China Welong's Downhole Drilling Tool Portfolio
The ranges below come from customer-supplied product files and help route an inquiry. Availability, model details, material, connection, inspection scope and delivery must be confirmed in the quotation.
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The trap: a range match is not always a product match when connection, material or inspection scope creates a mismatch. Because these nine cards combine 2 3/8 in drill pipe, 42 in hole-opening or reaming routes and other families, China Welong sources and inspects against the product-specific RFQ. For an operator, procurement team or QA reviewer, the drawing and accepted evidence remain the decision record.
Supplied-File Decimal Equivalents for RFQ Routing
| Family | Supplied fractional range | decimal equivalent | Use boundary |
|---|---|---|---|
| Drill Pipe | 2 3/8–6 5/8 in | from 2.375 in to 6.625 in | Inquiry routing only |
| Drilling Jars | 3 1/8–9 1/2 in | from 3.125 in to 9.5 in | Inquiry routing only |
| Drill Collar | 3 1/8–11 in | from 3.125 in to 11 in | Inquiry routing only |
Decimal values are conversions of the reference dimensions; model details, material, connection, inspection scope and delivery are confirmed in the quotation.
Drilling Stabilizer
- Integral-blade and sleeve forms are listed
- Supplied hole-size family runs from 6 to 42 in
- Confirm position, blade OD, material and hardfacing
Roller Reamer
- Hard, medium-hard and soft formation routes appear in files
- Model family extends to 42 in in the supplied table
- Match hole size, cutter form, connection and placement
Hole Opener
- Supplied model table spans pilot-to-opened-hole duties
- Family entries extend to 42 in
- Ambiguous source connection cells are excluded until confirmed
Drilling Mud Motor
- Drilling mud motors use a positive-displacement motor route
- Supplied files list 1 7/8-9 5/8 in and 120-150C entries
- Carry limits forward only after model, fluid, flow and duty review
Drilling Jars
- Hydraulic up/down jar family
- Supplied files list 3 1/8–9 1/2 in OD models
- Confirm impact direction, load window and placement
Heavy Weight Drill Pipe
- Transition weight and stiffness in the drill string
- Supplied size family runs from 3 1/2 to 6 5/8 in
- Friction-welded and integral forms appear in the source set
Drill Collar
- Supplied files list 3 1/8–11 in OD
- 4145H/4145H MOD and non-magnetic options are listed
- Choose slick or spiral form with required bore/connection
Non-Magnetic Drill Collar
- Variant route for measurement-sensitive assembly sections
- Use "non magnetic drill collar" in RFQ with material requirements
- Current card routes to the Drill Collar page
Drill Pipe
- Supplied files list 2 3/8–6 5/8 in
- Grade options include E75, X95, G105 and S135
- Confirm tool joint, coating, hardbanding and API 5DP scope
Compare Drill-String Components Before You Specify Them
The honest limit: a longer drill collar is not always a predictable vibration fix, and a model limited to the BHA is not necessarily enough for critical-speed work. A common assumption says one anti-vibration tool solves the problem, but that hides a trade-off; this page will not claim catalog fit is industry truth.
Talk to an EngineerFour-component stop/go table
| Component | Primary RFQ question | System input that can change the answer | Stop condition |
|---|---|---|---|
| Drill Pipe | Which size, grade, tool joint and protection system? | Load path, hydraulics, rotary duty and connection compatibility | String loads or applicable scope are not defined |
| HWDP | Where is the stiffness/weight transition needed? | Neutral point, inclination, bending and connection sequence | Placement is based only on catalog dimensions |
| Drill Collar | Which OD, bore, length, material and profile? | WOB, RPM, vibration modes, well geometry and prior fatigue | Dynamic or fatigue context has not been reviewed |
| Stabilizer | Which form, blade OD and position? | Formation, directional response, contact and vibration trade-offs | Placement is treated as a universal vibration cure |
Jar inputs
- Stuck mechanism and event history
- Impact direction and available overpull
- Inclination, friction and string buckling context
- Circulation and placement constraints
Mud motor inputs
- Flow rate, pressure and drilling-fluid properties
- Target bit RPM and torque demand
- Temperature and bend setting
- Formation and application type
Reaming inputs
- Pilot hole and target hole size
- Formation and cutter route
- Connection, circulation and debris handling
- Placement and final-gauge acceptance
Failure-history inputs
- Stick-slip, whirl, shocks or bit bounce
- Connection damage, washout or thread-root fatigue
- Prior repair and service records
- Known weak point in the full string
Drill collar threads can become fatigue hot spots under severe vibration, but the risk depends on the assembly and drilling conditions. A single anti-vibration tool cannot eliminate every vibration mode, so placement and operating changes need a full-system review.
China Welong Manages Supply, Purchasing Supervision and Quality Control
Founded in 2001, China Welong is an international integrated supply-chain service provider for customized industrial metal products. This service scope covers supplier development and management, purchasing supervision and quality control; it does not make China Welong the licensed manufacturer of every quoted item.
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Ownership before assurance
License and scope ambiguity is a procurement risk because a generic API label can hide a manufacturer or facility mismatch. Unlike a direct-manufacturer claim, China Welong's service role keeps the supplier, facility and six evidence fields visible; the trap is treating quality control as transferred licensing.
Define the supply scope
- Tool family and service condition
- Specification and buyer requirements
- New, used, repaired or remanufactured status
Develop and qualify sources
- Actual manufacturer and facility
- Product and process capability
- Applicable license or approval scope
Supervise purchasing
- Drawing and order revision
- Inspection plan and hold points
- Exceptions, changes and buyer decisions
Control release evidence
- Material and item trace
- Inspection and test results
- Marking, packing and delivery records
Manufacturer
Legal entity responsible for the quoted product.
Facility
Location that made, serviced or released the item.
Quoted item
Exact family, model, size and supply condition.
Specification
Applicable edition plus buyer additions or exclusions.
Scope and status
Current licensed or approved range for that facility and product.
Marking and records
Evidence that ties the physical item back to its release file.
A
Keep product scopes separate
Official API addenda reviewed for this page identify Specification 5DP with drill pipe and 7-1 with rotary drill stem elements; 7-1 excludes drill pipe. A marking does not resolve licensing ownership by itself, so check the company, facility, product, scope and current status in the API Composite List.
Product and Inspection References
Specification and documentation review for downhole drilling tools
Use the RFQ Checklist to Prevent Specification Gaps
A mud-motor quote is hard to compare when flow, speed, torque, fluid and application inputs are missing. The same problem appears elsewhere in the portfolio when product identity, system context, lifecycle status or release evidence remains open.
Scenario: Motor Input Gap
- The requested OD and connection match a catalog family
- Flow, pressure, fluid properties and target bit speed remain open
- Route the question to engineering before model comparison
Scenario: Repaired Stabilizer
- The blade OD and connection are stated
- Repair scope, responsible facility and post-repair checks are missing
- Keep release status open until QA accepts the evidence package
Quote Boundary
A commercial quotation should separate confirmed items from points still open for technical review, and show which evidence is included, optional or buyer-supplied. An open system or conformity gate should never be presented as cleared.
10-Input RFQ Completeness Scorecard
Mark each line Ready, Open or Not Applicable. This is an input-completeness score, not a prediction of price, delivery or downhole performance.
0/10
01
Tool family, function and quantity
Open
02
OD, ID, length and model range
Open
03
Connection and adjacent components
Open
04
Material, grade and service environment
Open
05
Full string, BHA position and well geometry
Open
06
RPM, WOB, torque, flow and pressure
Open
07
Temperature, fluid and formation
Open
08
Supply condition and prior service
Open
09
Specification, inspection and release evidence
Open
10
Quantity, delivery point and commercial terms
Open ✓
RFQ source: ASME evidence for whole-string context before a critical-speed decision
Downhole Drilling Tools Selection & Verification Framework
Downhole Drilling Tool Family Selector
Choose the main job, the current decision stage and the required supply condition. Routing identifies a useful product family and the next input to validate.
10-Input Downhole Tool RFQ Completeness Checker
Start with the inputs already defined in your request. Comparison decisions become clearer when the first information gap has an owner.
FAQ About Downhole Drilling Tool Sourcing
What information should I send with a downhole drilling tools RFQ?
Begin with the product family, function, dimensions, connection, material, quantity and delivery point. Add string position, operating inputs, service environment, supply condition, applicable specification and expected inspection or release evidence. Mark unknown fields as open and name the team responsible for closing them.
Is API 5DP the same as API 7-1?
No. The reviewed API addenda identify 5DP with drill pipe and 7-1 with rotary drill stem elements; 7-1 excludes drill pipe.
Can product dimensions confirm that a tool will work in my BHA?
No. Dimensions and connections are screening inputs, while string dynamics, placement, RPM, WOB, torque, hydraulics, well geometry, formation and prior failures can change the decision. Treat a catalog match as the start of technical review, with final BHA suitability left to the responsible drilling engineer or independent design team.
How is a non-magnetic drill collar handled on this page?
It appears as a separate decision route because magnetic requirements and test evidence matter. Until a dedicated non-magnetic product URL is available, the card routes to the Drill Collar page.
Which quality records should I request?
Match the records to the product, supply condition and buyer specification. For new supply, connect material identity, dimensions, tests, marking and release status to the physical item; for used or repaired supply, add prior-service, classification and repair history. Each record set should identify the responsible manufacturer or facility and any exception accepted by the buyer.
What is China Welong's role in the transaction?
Welong coordinates supplier development, purchasing supervision and quality control. Manufacturing and licensing ownership remain with the actual quoted source.
Working with China Welong
Order Terms, Evidence and Next Steps
The commercial terms below apply to every oilfield tools order we quote. They are the same terms our quotation repeats back to you, so nothing on this page has to be re-negotiated once a drawing is on the table.
What we make, and from what
We work from 2D drawings and 3D CAD models (AutoCAD, Pro/ENGINEER and SolidWorks; .dwg and .igs).
Founded in 2001. Manufacturing at Xi'an, Shaanxi and at Jiyuan, Henan, with 30+ engineers on staff.
Forgings from 0.2 to 50 tons, finished to 0.01 mm machining precision. Material standards to ISO, BS, ASTM, ASME, DIN, JIS and GB.
How the price is set
Send a drawing and we reply within 24 hours; a drawing-based quotation follows in 1–3 working days.
Payment is T/T or L/C. We ship EXW, FOB, CFR or CIF; other Incoterms on request.
Orders ship in standard export wooden cases, or the packing you specify.
When it ships
Production lead times are confirmed with your quotation, based on quantity, process route and finishing scope.
We hold agreed items in stock and ship against your release to shorten delivery.
Who makes it, and who answers for it
Every quotation states whether the item is made in our own works or by an approved supplier we developed and supervise.
Material mills are re-audited every two years and approved by Welong before they run your order.
The evidence that travels with the order
An EN 10204-3.1B material certificate with chemical composition and mechanical properties, a dimensional measurement report, and UT and MT reports ship with your order.
Inspection is by coordinate measuring machine, ultrasonic, magnetic particle and X-ray.
Each piece carries a stamped serial number and stays traceable for five years to its chemical composition, mechanical properties and measurement report.
What to send to start
Send the drawing or a photograph of the part, the dimensions, the material requirement and the quantity to oiltools@welongpost.com, call +86 029 88331331 or message WhatsApp +86 135 7217 2362, or use the enquiry form on our contact page.
An engineer reviews it and comes back within 24 hours.
| Term | What we commit to |
|---|---|
| Quotation turnaround | Reply within 24 hours; drawing-based quotation in 1–3 working days |
| Production schedule | Confirmed with your quotation, by quantity, process route and finishing scope |
| Drawing formats | 2D drawings and 3D CAD models (.dwg, .igs) |
| Company | Founded in 2001 |
| Machining precision | 0.01 mm |
| Forging envelope | 0.2 to 50 tons |
| Serial traceability | 5 years, with the test coupon retained |
| Documents with shipment | EN 10204-3.1B certificate, measurement report, UT and MT reports |
