ⅠSleeve stabilizer introduce

In oil drilling, the centralizer is a key tool, mainly used to ensure that the casing, drill string or downhole tools remain centered in the wellbore to avoid problems such as poor cementing quality, wellbore friction or well deviation caused by eccentricity.

ⅡEngineering Industry

The material of the centralizer needs to adapt to the high temperature, high pressure, corrosion and wear environment in the well. Common materials include:

Metal material	Advantages	Application
Carbon/alloy steel	low cost, high strength	suitable for conventional drilling environments
Stainless steel	strong corrosion resistance	used in corrosive wells containing hydrogen sulfide (H₂S) and carbon dioxide (CO₂).
Aluminum alloy	lightweight	suitable for shallow wells or scenarios where the weight of the pipe string needs to be reduced.

Ⅲ.Main functions

1. Ensure the casing is centered
o During cementing operations, the centralizer forms a uniform annulus between the casing and the well wall, ensuring that the cement slurry is completely filled, preventing "channeling" (discontinuous cement ring), and improving the cementing quality.
2. Reduce friction resistance
o During drilling or casing, the centralizer supports the well wall to reduce the friction between the pipe and the well wall, preventing drill sticking or pipe wear.
3. Control well inclination
o In directional wells or horizontal wells, the centralizer is used in conjunction with the borehole assembly (BHA) to adjust the force direction of the drill bit and assist in controlling the wellbore trajectory.
4. Protect the well wall and pipe
o Reduce the scraping of the pipe on the well wall to prevent the well wall from collapsing; at the same time, avoid bending and deformation of the pipe due to eccentric force.
5. Optimize drilling efficiency
o Reduce friction torque and resistance, increase the lowering speed of the drill string, and reduce drilling energy consumption.

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IV. Typical application scenarios in oil drilling

1. Cementing operations
o Casing centralizers are essential tools for cementing, especially in inclined wells and horizontal wells, and need to be installed densely (usually 10-30 meters apart).
2. Horizontal wells/extended reach wells
o Use non-metallic centralizers (such as nylon spiral centralizers) to reduce the friction resistance between the pipe string and the well wall to prevent "support pressure".
3. High-temperature and high-pressure deep wells
o Use high-strength alloy steel or composite centralizers to withstand high temperatures (>200℃) and acidic gas corrosion.
4. Sand control wells
o Install centralizers on the outside of the screen to ensure that the screen is centered to prevent formation gravel from clogging the screen holes.

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V. Common types

1. Rigid centralizers
o Made of metal or hard plastic, it provides strong support and is suitable for vertical wells or low-curvature well sections.
2. Spring-type centralizer
o With elastic blades, it can adapt to irregular wellbores and is commonly found in horizontal wells and complex well types.
3. Spiral centralizer
o The outer surface is designed to be spiral, which has both the centering function and the function of assisting the circulation of drilling fluid.
4. Roller centralizer
o With a roller structure, it greatly reduces friction resistance and is used in ultra-deep wells or long horizontal sections.

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VI. Selection and precautions

• Wellbore conditions: Select the type and installation density of the centralizer according to the wellbore diameter, well inclination, and dogleg degree.
• Environmental requirements: Stainless steel or composite materials should be used in high temperature and corrosive environments.
• Regulatory standards: Must comply with API SPEC 10D (International Petroleum Association Casing Centralizer Specification).

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Summary: The centralizer in oil drilling is a core tool to ensure wellbore quality, improve cementing success rate and drilling efficiency. Its material and design must match the depth of the well conditions, especially in complex well types.