Product Overview
The Concave Mill is a recessed stepped inner-center centralizing fish junk milling shoe specially developed for coiled tubing downhole composite fracture ball and ball seat milling grinding remedial workover operations.
The front working end of the concave mill adopts an outer-high inner-low stepped concave recess profile design; the stepped recessed surface naturally gathers and centralizes all types of downhole fallen fish junk fragments under the central cutting zone of the mill shoe, realizing concentrated high-efficiency cutting and crushing of junk fragments, which greatly improves overall milling penetration efficiency compared with conventional flat-bottom milling shoes. Each flow port distributed on the tool body is precisely optimized through full-flow field computational fluid dynamics (CFD) simulation analysis; the optimized flow hole layout effectively suppresses vortex turbulence phenomenon inside the fluid flow passage, improves the uniformity of wellbore circulating fluid flow field distribution, and significantly enhances the flushing and cleaning effect of circulating fluid on milled debris and cuttings at the bottom of the well. A full range of different hardness tungsten carbide hard alloy cutting particle specifications are provided for free interchangeable selection to adapt to different downhole rock hardness and junk fragment hardness construction demands.
The Concave Mill has no complex internal movable friction components, spring energy storage assemblies or differential pressure release mechanisms, with extremely simplified wellsite operation flow and low maintenance cost; construction crews only need to run the concave milling shoe down along the wellbore until the front stepped concave recess surface contacts the target composite fracture ball or ball seat, apply rotary torque and continuous circulating well fluid to realize centralized junk fragment crushing and continuous wellbore fluid circulation flushing work, no additional auxiliary operation steps such as drop ball delivery or shear pin impact jarring are needed, shortening wellsite operation time and reducing human error risks.
The standardized product lineup covers outer diameter sizes ranging from 2-7/8" to 5-1/2", with complete outer diameter specification series to match different wellbore inner diameter constraint conditions and different composite fracture ball / ball seat milling construction demands. Custom outer diameter, tungsten carbide cutting particle hardness grade and base material corrosion resistance grade customization are available upon customer technical drawing submission.
Complete Technical Specification Table
| PN Part Number | Outer Diameter OD | Make-Up Length | Working Condition Grade | Bottom Connection Thread |
|---|---|---|---|---|
| Custom PN Series | 2-7/8" | Custom Length | STD Standard | Custom Coiled Tubing Thread |
| Custom PN Series | 3" | Custom Length | STD Standard | Custom Coiled Tubing Thread |
| Custom PN Series | 4" | Custom Length | STD Standard | Custom Coiled Tubing Thread |
| Custom PN Series | 5-1/2" | Custom Length | STD Standard | Custom Coiled Tubing Thread |
Note: Custom outer diameter, tungsten carbide cutting particle hardness grade and base material corrosion resistance grade modification concave recessed milling shoes are available via engineering consultation. Two working condition grades (STD standard carbon steel / H₂S sour service anti-corrosion alloy) are optional for each outer diameter size, and the working condition grade needs to be clearly confirmed according to the downhole wellbore fluid H₂S concentration corrosive environment during order placement; multiple different hardness tungsten carbide cutting particle specifications can be freely matched on the cutting surface according to different downhole rock and junk hardness construction demands.
Core Features & Advantages
Outer-High Inner-Low Stepped Concave Recessed Front End Centralizing Design: The front working end of the concave mill adopts unique outer-high inner-low stepped concave recess profile, the stepped recessed surface naturally gathers and centralizes all types of downhole fallen fish junk fragments under the central cutting zone of the mill shoe, realizing concentrated high-efficiency cutting and crushing of junk fragments, which greatly improves overall milling penetration efficiency compared with conventional flat-bottom milling shoe products.
CFD Computational Fluid Dynamics Optimized Flow Port Layout Design: The position and inner diameter size of each flow port distributed on the tool body are precisely optimized through full-flow field computational fluid dynamics simulation analysis; the optimized flow hole layout effectively suppresses vortex turbulence phenomenon inside the fluid flow passage, improves the uniformity of wellbore circulating fluid flow field distribution, and significantly enhances the flushing and cleaning effect of circulating fluid on milled debris and cuttings at the bottom of the well.
Multiple Interchangeable Tungsten Carbide Hard Alloy Cutting Particle Grade Configuration: A full range of different hardness tungsten carbide hard alloy cutting grain specifications are provided for free interchangeable selection to adapt to different downhole rock hardness and junk fragment hardness construction demands, realizing flexible matching of milling cutting force and wear resistance performance according to actual downhole working conditions.
Full Outer Diameter Size Range Coverage: The applicable outer diameter size range of the concave recessed milling shoe covers 2-7/8" to 5-1/2", with complete outer diameter specification series to match different wellbore inner diameter constraint conditions and different composite fracture ball / ball seat milling construction demands.
Ultra-Simplified Wellsite Operation Logic: The concave milling shoe has no complex internal movable friction components, spring energy storage assemblies or differential pressure release mechanisms, the operation flow is highly streamlined: only need to run the concave milling shoe down along the wellbore until the front stepped concave recess surface contacts the target composite fracture ball or ball seat, apply rotary torque and continuous circulating well fluid to realize centralized junk fragment crushing and continuous wellbore fluid circulation flushing work, no complex auxiliary operation steps such as drop ball delivery or shear pin impact jarring are needed to shorten wellsite operation time and reduce human error risks.
Low Routine Maintenance Design: The integral cylindrical alloy steel tool body eliminates vulnerable split assembly movable wear parts; after each composite fracture ball / ball seat milling operation, only simple surface concave recess debris cleaning and flow port passage blockage flushing inspection are required, no complex disassembly, internal tungsten carbide cutting particle replacement or spring preload adjustment maintenance procedures, greatly reducing daily maintenance labor and spare parts inventory cost.
Application Scenarios
1. Coiled tubing downhole composite fracture ball and ball seat milling grinding heavy-load intervention treatments, including composite fracture ball, solid ball seat and other plug-type downhole obstacle milling and removal remedial workover construction operations
2. Conventional sweet crude oilfield outer-high inner-low stepped concave recessed centralizing milling shoe composite fracture ball and ball seat milling grinding remedial workover service (STD Standard carbon steel working condition grade)
3. High-sulfur H₂S containing corrosive downhole wellbore construction project composite fracture ball and ball seat milling heavy workover projects requiring H₂S sour service anti-sulfide stress cracking high-corrosion-resistant alloy material grade
4. Long-term continuous repeated rotary milling cutting load safety protection for coiled tubing bottom-hole assemblies in onshore and offshore oilfield composite fracture ball and ball seat milling grinding remedial workover intervention projects
Standard Delivery Package
Complete concave recessed stepped inner-center centralizing milling shoe integral alloy steel pre-assembled unit including main tool cylinder body and front outer-high inner-low stepped concave recess cutting surface embedded with interchangeable tungsten carbide hard alloy cutting particles
Spare interchangeable tungsten carbide hard alloy cutting particle maintenance kit with multiple hardness specifications for on-site cutting surface worn cutting grain replacement
Full factory inspection test report including repeated rotary milling cutting load fatigue resistance test, integral tensile load test, CFD flow port circulation flushing efficiency calibration test and stepped concave recess centralizing junk fragment crushing performance test data
Product dimension drawing and official installation & operation instruction manual, with detailed on-site composite fracture ball and ball seat milling grinding operation guidance, with clear reminder to select STD standard carbon steel grade or H₂S sour service anti-corrosion alloy grade according to downhole wellbore fluid H₂S concentration corrosive environment during order placement, and confirm required tungsten carbide cutting particle hardness grade according to different downhole rock and junk hardness construction demands
Quality Warranty & After-Sales Service
Warranty Coverage: 12 months after factory shipment or 2000 cumulative rotary milling cutting load cycles, whichever condition is reached first
Full factory inspection: Each finished concave recessed milling shoe passes integral tensile load test, repeated rotary milling cutting load fatigue test, CFD flow port circulation flushing efficiency calibration test and stepped concave recess centralizing junk fragment crushing performance test before factory delivery
Free professional technical support: Our oilfield downhole tool engineering team provides coiled tubing composite fracture ball and ball seat milling grinding remedial workover tool string matching, outer diameter & working condition grade (STD / H₂S) selection consultation free of charge
Long-term spare parts supply: All interchangeable tungsten carbide hard alloy cutting particle wear accessories are stocked with competitive factory bulk pricing
Custom development service: Support custom outer diameters, customized tungsten carbide cutting particle hardness grade specifications, base material corrosion resistance grade modification, bottom coiled tubing connection thread profiles and special size concave recessed milling shoes based on customer technical drawings
FAQ
Q1: What is the core function of a Concave Mill (Stepped Recessed Inner-Center Centralizing Milling Shoe)?
The Concave Mill is a stepped outer-high inner-low concave recessed centralizing fish junk milling shoe dedicated to coiled tubing downhole composite fracture ball and ball seat milling grinding remedial workover operations. The front stepped concave recess profile naturally gathers and centralizes downhole fallen fish junk fragments under the central cutting zone of the mill shoe to realize concentrated high-efficiency cutting and crushing of junk fragments and improve overall milling penetration efficiency. Each flow port is precisely optimized through computational fluid dynamics (CFD) simulation analysis to suppress vortex turbulence and boost well fluid circulation flushing cleaning effect. A full range of different hardness tungsten carbide hard alloy cutting particle specifications are available for free interchangeable selection to adapt to different downhole rock hardness and junk fragment hardness construction demands. The applicable outer diameter size range covers 2-7/8" to 5-1/2". Two independent working condition material grade options are provided: STD standard carbon steel grade for conventional non-corrosive wellbore environments without high-concentration H₂S corrosive medium; H₂S sour service high-corrosion-resistant alloy grade for high-sulfur H₂S containing corrosive downhole wellbore construction conditions. No complex internal movable friction components or spring assemblies are equipped, operation flow is highly simplified, widely applied for coiled tubing downhole composite fracture ball and ball seat milling grinding remedial workover construction operations.
Q2: What three core structural advantages does this Concave Mill Stepped Recessed Milling Shoe own?
1. Outer-high inner-low stepped concave recessed front end centralizing design, the front working end of the concave mill adopts unique outer-high inner-low stepped concave recess profile, the stepped recessed surface naturally gathers and centralizes all types of downhole fallen fish junk fragments under the central cutting zone of the mill shoe, realizing concentrated high-efficiency cutting and crushing of junk fragments, which greatly improves overall milling penetration efficiency compared with conventional flat-bottom milling shoe products; 2. CFD computational fluid dynamics optimized flow port layout design, the position and inner diameter size of each flow port distributed on the tool body are precisely optimized through full-flow field computational fluid dynamics simulation analysis; the optimized flow hole layout effectively suppresses vortex turbulence phenomenon inside the fluid flow passage, improves the uniformity of wellbore circulating fluid flow field distribution, and significantly enhances the flushing and cleaning effect of circulating fluid on milled debris and cuttings at the bottom of the well; 3. Multiple interchangeable tungsten carbide hard alloy cutting particle grade configuration & ultra-simplified wellsite operation logic, a full range of different hardness tungsten carbide hard alloy cutting grain specifications are provided for free interchangeable selection to adapt to different downhole rock hardness and junk fragment hardness construction demands; the concave milling shoe has no complex internal movable friction components, spring energy storage assemblies or differential pressure release mechanisms, only need to run the concave milling shoe down along the wellbore until the front stepped concave recess surface contacts the target composite fracture ball or ball seat, apply rotary torque and continuous circulating well fluid to realize centralized junk fragment crushing and continuous wellbore fluid circulation flushing work, no complex auxiliary operation steps such as drop ball delivery or shear pin impact jarring are needed to shorten wellsite operation time and reduce human error risks; the product also features full outer diameter size range coverage and integral cylindrical tool body low maintenance design to further optimize on-site construction efficiency and reduce post-operation maintenance workload.
Q3: What outer diameter sizes and configurable options do these Concave Mill Stepped Recessed Milling Shoes support?
Our standard applicable outer diameter size range covers 2-7/8", 3", 4" and 5-1/2". Each OD size supports two independent working condition material grade versions for free matching selection: STD standard carbon steel working condition grade and H₂S sour service high-corrosion-resistant alloy working condition grade. All models support custom coiled tubing bottom connection threads compatible with global mainstream coiled tubing connector assemblies and other supporting downhole composite fracture ball and ball seat milling remedial workover tools. Custom tungsten carbide cutting particle hardness grade specifications and base material corrosion resistance grade specifications are available upon customer downhole wellbore fluid H₂S concentration corrosive environment and downhole rock/junk hardness construction demands.
Q4: What is the standard production lead time for bulk purchase orders?
All standard PN part numbers are kept in factory inventory, goods can be delivered within 7–15 working days. Customized concave recessed milling shoes with special outer diameters or customized tungsten carbide cutting particle hardness grade specifications, base material corrosion resistance grade specifications & bottom connection thread profiles require 20–35 working days production cycle, subject to total order quantity and customization scope.
Get Custom Datasheet & Factory Quote
We are a professional OEM & ODM manufacturer focused on full series coiled tubing heavy workover and washing downhole service tools, covering concave stepped recessed centralizing milling shoes, five-blade five-wing milling shoes, flat bottom milling shoes, combination flat blade milling shoes, magnetic fishing rods, magnetic junk retrieval magnets, venturi junk baskets, flow activated releasable fishing overshots, flow activated releasable fishing spears, flow activated releasable JDC running/pulling tools, flow activated releasable GS fishing tools, bi-direction mechanical accelerators, bi-direction hydraulic accelerators, bi-direction hydraulic jars, up-stroke hydraulic jars, bi-direction mechanical jars, up-stroke mechanical jars, wireline grabs, wireline spears and all other supporting downhole fishing, jarring, anchoring and washing service tools. Every finished product undergoes strict factory tensile load, repeated rotary milling cutting load fatigue, CFD flow port circulation flushing efficiency calibration and stepped concave recess centralizing junk fragment crushing performance testing, with complete material inspection certification attached to each shipment. Please share your detailed technical requirements, including target outer diameter size, required working condition grade (STD standard carbon steel / H₂S sour service anti-corrosion alloy), required tungsten carbide cutting particle hardness grade, downhole wellbore fluid H₂S concentration corrosive environment construction conditions, working environment and all customized specification demands. Our dedicated oilfield downhole tool engineering team will send complete detailed technical datasheets and competitive factory wholesale quotations within 24 business hours, and provide professional on-site composite fracture ball and ball seat milling grinding operation guidance, with clear confirmation reminder for working condition grade selection (STD standard carbon steel for non-corrosive well / H₂S sour service anti-corrosion alloy for high-sulfur corrosive well) and tungsten carbide cutting particle hardness grade confirmation according to different downhole rock and junk hardness construction demands during order placement.
