The cementing plug is a key component in cementing operations, and its core role can be summarized in the following four aspects:

Isolation of fluids

The plug is placed between the drilling fluid and cement slurry during cementing, preventing the two from mixing in advance and ensuring the cement slurry top replacement effect and cementing quality. In addition, it prevents the cement slurry from being contaminated by subsequent replacement drilling fluids and safeguards the cement cementing strength at the bottom of the casing.

Cleaning the casing wall

The casing wall is scraped by physical contact during the downward movement of the rubber plug to remove any residual cement slurry or adherents, keeping the inside of the casing clean and minimizing the interference of impurities that may exist after cementing.

Touch pressure indication

When the plug reaches the flow stopper at the bottom of the casing, it is crushed due to the obstruction of the reducer, resulting in a sudden rise in the pump pressure (i.e., “touch pressure”), which signals that the cement slurry has been completely injected into the predetermined position and the cementing operation is completed.

Adaptability of structure

According to the specific requirements of working conditions, the rubber plug can be divided into ordinary type and anti-rotation type. The anti-rotation plugs are specially designed to improve drilling and removal efficiency and are suitable for drilling and removal with PDC or tooth wheel drills. Some models also adopt wear-resistant material scraping wings and double-stage sealing structure to further enhance reliability.

The material design of Cementing Plugs is based on functional requirements and process characteristics, and mainly includes material selection for the following structural components:

Core material

The internal skeleton of cementing plugs is usually made of aluminum alloy, polymer materials (e.g. phenolic resin) or fiberglass composites, which combine high strength and ease of drilling, facilitating subsequent drilling and removal operations. Some designs are compression molded at high temperatures and pressures to ensure structural stability.

External Rubber Layer

The outer rubber layer of the plug is made of vulcanized nitrile rubber, which is resistant to oil, acid and alkali, as well as abrasion, effectively adapting to the complex downhole environment. Some models have polyurethane scraping wings to enhance casing cleaning ability.

Auxiliary Component Materials

The anti-rotation mechanism of anti-rotation rubber plugs may be made of high-strength composite materials to improve drilling and removal efficiency.

Components such as sealing plugs utilize a shear-nail control mechanism and are made of materials that meet the need for precise manipulation.

All materials in the overall design need to be easy to drill and suitable for removal by PDC or tooth wheel drills.

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