Non-magnetic Rotating Guide Shell

I. Core functions and roles

1. Magnetic shielding protection: The shell is made of low magnetic permeability material (magnetic permeability μ≈1) to avoid ferromagnetic interference from itself and the drill string, providing a "magnetic transparency" environment for MWD/LWD geomagnetic measurement, ensuring accurate data such as azimuth angle and wellbore inclination angle.

2. Structural load-bearing and sealing: The non-magnetic rotating guiding shell can withstand high temperatures (120-180 ℃), high pressures (100-140MPa), vibrations, and torques underground, protecting the internal guiding drive, control modules, and sensors. At the same time, it seals the drilling fluid to prevent mud from entering and damaging components.

3. Adaptation to guiding actions: Match with guiding actuators (such as push type stabilizing blocks and eccentric mechanisms) to transmit lateral forces during rotary drilling, achieving real-time control of wellbore trajectory.

4. Compatibility with drill string connection: Both ends are designed with threads according to API standards, which can be quickly connected to non-magnetic drill collars, drill bits, and other components to ensure the overall mechanical transmission and operational safety of the drill string.

II. Key points of structural design

1. Infrastructure: Non magnetic rotating guiding shells are mostly thick walled cylindrical, including internal installation chambers, threaded joints, supporting surfaces, sealing grooves, and some with eccentric channels or stabilizing block windows, suitable for the installation and action space of guiding mechanisms.

2. Key tolerances: Inner diameter tolerance 0-3 μ m, outer diameter tolerance ± 2 μ m, surface roughness Ra ≤ 0.2 μ m, thread accuracy meets API Spec 7/7G, ensuring sealing and connection reliability.

III. Selection suggestions

1. Measurement accuracy priority: Choose 20Mn23AlV or Monel alloy with μ ≤ 1.02, suitable for high-precision LWD.

2. Deep/high-temperature wells: Choose nickel based non-magnetic alloys with a temperature resistance of ≥ 180 ℃ and stronger corrosion resistance.

3. Economic project: Choose 20Mn23AlV, balance cost and performance, and adapt to conventional directional wells.