Annular blowout preventer is also called multi-function blowout preventer. When the well is closed, the annular rubber core is evenly squeezed into the center of the wellbore, which has the advantages of high pressure bearing, reliable sealing, convenient operation, and rapid switching. It is especially suitable for sealing various types and sizes of pipe strings, but also fully closed wellheads.
The annular blowout preventer can be divided into a taper rubber core, a spherical rubber core and a tubular rubber core blowout preventer.
1. Tapered rubber core annular blowout preventer
1) Structure
Tapered rubber core blowout preventer is mainly composed of shell, supporting tube of plastic core, piston, rubber core, top cover, dustproof ring, bolt, cover plate, hanging ring, retaining ring, upper joint and lower joint. Tapered rubber core BOP structure shown in Figure 1.
Tapered rubber core annular blowout preventer
1. Top cover; 2. Rubber core; 3. Dust ring; 4 piston;
Figure 1 Tapered rubber core annular blowout preventer structure
2) Working principle
When it is in use, it is operated by hydraulic pressure. The pressure oil of the hydraulic system enters the liquid cylinder through the lower joint on the shell and pushes the piston upward. As the piston cone pushes the rubber core, the top surface of the rubber core is limited by the top cover. , The rubber core shrinks tightly around the pipe string, or completely seals the space when there is no pipe in the well. When it is necessary to open, the hydraulic system is operated so that the pressure oil enters the upper cylinder from the upper joint, and the lower cylinder returns to the oil, the piston descends, the plastic core gradually recovers its original shape under the action of elasticity, and the wellhead opens. This blowout preventer generally completes the shut-in action time less than 30s, and the opening time is slightly longer.