Floating hoop and shoes are the key tools for casing cementing operation, and their core functions and characteristics can be summarized as the following five aspects:

I. Core Functions

Guiding casing into the well

Floating shoes are located at the end of casing column, and the hemispherical design can effectively guide the casing string to be lowered smoothly and reduce the friction resistance with the well wall, which is especially suitable for complex borehole trajectories.

Adjusting buoyancy and sealing to prevent backflow

The buoyancy of the casing string is automatically balanced by an internal check valve, which reduces the pressure on the bottom of the well from its own weight.

After cement injection is completed, the pressure return valve closes to prevent cement slurry or drilling fluid from flowing back into the casing, ensuring the integrity of the cement ring.

Cement plug height control

The floating hoop serves as a rubber plug touching seat, which can accurately limit the height of the cement plug in the casing to ensure the quality of cement bonding in the casing shoe area.

Plug Support and Pressure Indication

When injecting cement, the floating hoop provides the position of the rubber plug touching pressure, and confirms the completion of cement slurry injection through the signal of sudden increase of pump pressure.

Structural design features

Drillability and adaptability of diameter

Internal components (e.g. spool, spring, etc.) are designed with drillable materials, and the through diameter is consistent with the casing, which is convenient for subsequent drilling and removal operations.

Anti-rotation design optimization

The anti-rotation floating shoe is optimized to enhance drilling efficiency through the combination of the internal anti-rotation flower head and anti-rotation rubber plug, which is suitable for PDC drilling operations.

Material Strength and Sealability

The material strength is equivalent to API P-110 steel grade, which meets the requirements of high-pressure well conditions.

Vulcanized rubber spool and alloy valve seat form a reliable seal, resistant to acid and alkali corrosion and high temperature.

Application Scenarios

Adaptability to complex well conditions

By improving the spool material (e.g. alloy or high-temperature resistant composite material), the floating shoe can be used in ultra-deep wells, horizontal wells and other complex wells.

Matching use specification

Floating shoes are usually installed at the bottom of the casing column, while the floating hoop is connected with 1-2 casing at intervals to form a double backflow prevention guarantee.

Translated with DeepL.com (free version)