Milling Cone for Sidetrack Drilling

I. Core functions and workflow

1. Core functionality.

Casing cutting: Efficiently grinding through the casing wall to create a window that allows subsequent drilling tools to pass through.

Window trimming: Shape a smooth, regular tapered opening to avoid steps and the risk of stuck pipe.

Stable guidance: Achieve directional cutting in coordination with the inclined cutter to ensure precise window orientation.

2. Standard operating procedures.

Install the inclined device and anchor it to establish a guiding slope.

Insert the milling cone and perform window milling according to the parameters (drilling pressure 5-15kN, rotational speed 80-120rpm, flow rate adjusted to the wellbore).

Expand and repair window to ensure smooth and burr-free surfaces.

Pull out the tools and sidetrack a new wellbore.

II. Key points in design and manufacturing

1. Structural parameters: Cone angle matches the inclination angle (commonly 5°-15°), gauge band width 8-15mm, cutting teeth arranged helically for efficient chip removal.

2. Key tolerances: Outer diameter tolerance ±0.5mm, surface roughness Ra≤0.8μm, threads conform to API Spec 7 standard.

3. Processing flow: Raw material flaw detection → CNC machining → cutting tooth, welding / embedding → heat treatment → radius maintenance treatment → performance testing.

III. Selection and quality control

1. Selection principles.

Casing steel grade: P110, high-grade steel grades such as P110 should select PDC/diamond composite milling cones; J55/N80 can opt for tungsten carbide milling cones.

Wellbore conditions: For deep wells, select models with a temperature resistance of ≥150°C; for short-radius sidetracking, choose integrated mill cones.

Window dimensions: The outer diameter of the milling cone must be at least 8mm larger than the tailpipe coupling to avoid steps.

2. Quality inspections.

Testing of cutting tooth adhesion strength and wear resistance of retaining tape.

Non destructive testing (ultrasonic/magnetic powder) to identify cracks.

Ground simulation milling test to verify cutting efficiency and window quality.