Working principle of the Annular Blowout Preventer
The annular blowout preventer is operated by the hydraulic control system. When it’s closed, high pressure oil comes from the middle oil part of the shell into the lower closing cavity of the plunger, pushing the plunger upward, and cone plunger squeezes the rubber core, because of the limitation of the top cover, rubber core can’t uplink but can only be pushed to the center of the well, until hold drilling tools or close the whole wellhead to achieve the goal of sealing the well.
When the well is needed to open, directional control valve in hydraulic control system shall be operated, which makes high pressure oil come from the upper part of the shell to upper open cavity of plunger, promote the plunger downward, and close cavity to discharge pressure. The extrusion pressure in rubber core is eliminated, and then the rubber core is gradually reset under the elastic force of itself, thus opening the wellhead.